Method and apparatus for disinfecting waste liquids

(54) Name: Procedure and ejector type contact chamber apparatus for disinfection of flowing sewage □ Completed international patent application with number

O converted European patent application with number

75-04-07 US 565872

US (56) Published publications:

CH 599 054

DE 2 055 020

DE 1,517,440

US 3,833,719

7511341-5

The present invention relates to waste treatment and in particular to the disinfection of liquid waste, e.g. municipal sewage, using disinfectants, e.g. ozone or chlorine.

For many years, chlorine has been recognized as a good disinfectant and has been used in one form or another in most microorganism-free water production systems. For example, in almost all modern wastewater treatment plants chlorine is used to reduce the number of bacteria in the pre-treated stream before being removed from the system, usually to a river or river. A chlorination plant or chlorination system can also be used to remove color, correct flavors, remove odor and suppress other types of unwanted biological growth. Chlorine is also widely used in the treatment of industrial waste and water.

Recent advances have been made in the chemistry of water chlorination. It is known that this chemistry is relatively complex, and you can get an overview of different aspects of the chemistry of water chlorination in Chemistry and Control of Modern Chlorination ”by AT Palin (1975). It is known that chlorine is a good disinfectant when used in liquid waste in the form of a solution of chlorine gas (Clg) in water. When chlorine is added to water, it rapidly hydrolyses and forms hydrochloric acid

7511341-5 (HC1) and subchloric acid (HOC1), the latter partially dissociates to give hydrogen ions and hypochlorite ions (H⁺ and 0C1^-). These three forms of available chlorine, namely molecular chlorine (Cl 2, non-ionized subchloric acid (HOC1) and hypochlorite ion (OC1)) exist together in equilibrium; their relative ratio is determined by the pH and temperature of the water. free chlorine reacts relatively quickly with different types of waste water components, which include certain nitrogen and hydrocarbon compounds. The hypochlorite forms of free chlorine compounds are known to act more strongly than the compound forms obtained by reaction with compounds contained in the wastewater to be treated. It is also believed that dissolved molecular Cl₂ is a very powerful disinfectant, but molecular chlorine does not appear in large quantities under equilibrium conditions at the pH value of most wastewater. The pH value must be lowered to a relatively low value to enable molecular Cl₂ can be in solution in significant concentrations. Treatment of large flows of wastewater at low pH is generally too expensive, especially if subsequent neutralization treatment is also necessary.

Two of the most important performance and operating parameters with respect to conventional large-scale disinfection systems are chlorine dosing or concentration, and contact or residence time, which relates to the length of time during which the chlorine-treated flow is retained in a contact tank. Determination of the chlorine dose or concentration involves balancing various factors, e.g. increased kill rate or reduced contact time, obtained with high chlorine dosage, relative to higher disinfectant costs. It is not desirable to have large amounts of residual chlorine and various chlorination products obtained from treatment with high chlorine doses.

JO In this regard, residual chlorine and chlorination by-products, e.g. chlorinated amines and hydrocarbons, all the less desirable for environmental degradation.

Taking into account such factors as initial cost, space requirements and residence time, and chlorine dose size, an optimization of current chlorine contact tanks generally includes providing a serpentine-like multichannel path, along which flow travels with a residence time of 15-30 minutes. The disinfection is done by introducing an aqueous chlorine solution at the inlet through which the flow enters the chlorine contact tank.

Relatively late studies have shown that, with respect to

-341-5 on disinfecting flows from waste treatment systems, initial flash mixing of flows with HOC1 and OC1 ”, as the flow enters a conventional chlorine contact tank, the killing rate of bacteria and viruses increases in the flow. The Enhancement of Viral Inactivation by Halogens by CW Kruse, VP Olivieri & K. Kawata, Water and Sewage Works, p 187-193 (June 1971) and Kinetics of Wastewater Chlorination in Continuous Flow Processes by RE Selleck, HF Collins and G. White, presented at the 5th International Water Pollution Research Proceedings (July, August 1970) refers to such relatively late research with respect to such initial or flash mixture. Perhaps the newest and most comprehensive study on chlorine disinfection is described in an article titled Improvement in Terminal Disinfection of Sewage Effluents published in the June-1973 issue of Water Sewage Works Relating to Work carried out at Sewage Treatment Plant No 2, Fort Meade, Maryland, in 1972 by CW Kruse, K. Kawata, VP Olivieri and KE Longley at the Department of Environmental Health, John Hopkins School of Hygiene and Public Health, Baltimore, Maryland. The emphasis of the conclusions drawn by the authors of the previous article is that the disinfection can be improved by improving the mixing of liquid waste aqueous chlorine and by lowering the pH of the chlorine reaction.

The investigations resulting in the present invention are also performed in part at the Department of Environmental Health, John Hopkins School of Hygiene and Public Health and at Fort Meade Sewage Treatment Plant No. 2, The original object of investigation included wastewater effluent treatment with a nozzle mixture and using venturi pipe principles, in which treatment the aqueous chlorine solution was used as a propellant flow. This initial work, performed over a 10-month period with both municipal wastewater and synthetically prepared bacteria and virus flows, did not produce any significant improvements beyond the results reported by Kruse et al. However, these preparatory tests resulted in substantial amounts of drive current being required to achieve a desired mixing effect, and that the flow rate of the aqueous chlorine solution necessary to give rise to this effect substantially exceeded the flow rate which could give a acceptable level of chlorine dosing. Moreover, although a substantial amount of diluted disinfection solution could be used, this would increase the need for diluted water and correspondingly increase the final effluent flow. It was also concluded that use

The provision of a turbulent flow zone through which the entire flow to be treated could increase disinfection due to better and more thorough mixing of the aqueous chlorine and flow. During these investigations, it was also decided that direct introduction of chlorine gas and ozone, instead of aqueous chlorine solution, into a turbulent zone for mixing the flow would be studied. Accordingly, more complex mixing systems and methods with ejectors were investigated. In the following work, a portion of the waste liquid to be treated was used as a propellant, and aqueous chlorine was peripherally introduced around the propellant liquid jet. The structure was thus that two concentric nozzles opened into the mixing chamber, the inner nozzle emitted a jet of waste liquid at a relatively high speed and the other or peripheral nozzle emitted a jet of aqueous chlorine solution.

15th This two-nozzle mixing system provided the ability to independently control the mixing effect and amount of disinfection solution, and disinfection methods using a turbulent mixing zone and direct supply of chlorine gas or ozone to the flow were also investigated. It was also found that the methods and apparatus developed and improved over the course of the present work provided significant advantages in wastewater disinfection with respect to disinfection time, disinfection dose, and bacterial and virus killings for a given dose of disinfectant. In addition, in most of the currently existing chlorine disinfection systems, the large expensive contact chambers can be reduced or eliminated in size, while the performance of existing chlorine disinfection contact chambers can be substantially increased without major modifications. At present, chlorine disinfection generally provides favorable results with respect to microbial killing and various other benefits which can be obtained using chlorine. Nevertheless, improvements in connection with various aspects of wastewater disinfection, e.g. the time required and the cost of achieving satisfactory disinfection, the completeness of the disinfection, the necessary amount of chlorine to obtain satisfactory disinfection, and the amounts of residual chlorine and chlorination by-products obtained in the chlorination are very desirable.

Accordingly, the present invention relates to improved methods and apparatus for disinfecting waste liquids, e.g. the treated solution from a municipal sewage treatment plant.

The present invention relates to method and apparatus

7511341-5 for the disinfection of flowing sewage, in which liquid or gaseous disinfectant and flowing sewage to be disinfected continuously may pass through a turbulent mixing zone. The unique and distinctive feature of the process is that it comprises the steps of continuously mixing and passing flowing sewage to be disinfected and a disinfectant at an effective dose level for treating sewage through a turbulent mixing zone while maintaining a turbulence ·? level in the turbulent mixing zone such that the mixing rate in the mixing zone is at least 5 seconds to provide a turbulent mixed product stream with a substantially uniform toxic environment for inactivation of organisms, wherein the turbulent mixing zone is generated by introducing at least one driving stream of a smaller portion of the flowing sewer water to be treated into an impact zone which is fed with the greater portion of the flowing sewer water to be treated, wherein the ratio of the volumetric rate of induction of flowing sewage water from the actuating zone into the turbulent mixing zone to the volumetric flow rate of the driving stream is in the range of 1.4: 1 to 23: 1 and the velocity of the driving current introduced into the the impact zone is at least about 5.2 m / sec, and the turbulent mixed flowing sewage water and the disinfectant product stream are conducted from the mixing zone to provide, a treated outlet stream said that the average residence time j of the turbulent mixing zone of said product current as the conductor. of the outlet stream is maintained, thereby excluding from the outlet stream flowing sewage water which has not passed through the turbulent mixing zone of a11 to provide treated effluent product. The apparatus is characterized in that it comprises container-separator wall means for insulating a pump pit zone at the inlet end of the contact chamber means from a downstream treated sewage water contact chamber zone, whereby the diverting wall means comprises a flow pipe including a mixing pipe and means forming a liquid nozzle for receiving a minority of the flowing sewage water which

7511341-5 should be treated to provide a propellant jet discharged from the nozzle outlet into the pump pit zone and directed to the conduit and waterproof pump means located in the pump pit zone for pumping the smaller portion of the flowing sewage water from the pump pit or through the nozzle zone through liquid disinfectant into the driving jet wherein ratios of the cross-sectional area of ​​the mixing path to the cross-sectional area of the nozzle is from about 25: 1 to about 169: 1.

The present invention is further described in the detailed description and in conjunction with the accompanying drawings, in which Fig. 1 is a plan view, partially schematic, of an older disinfection system; Fig. 2 is a cross-sectional view of one embodiment of the present disinfection system; Fig. 3 is a cross-sectional view of one embodiment of a double nozzle hydrodynamic mixer for treating aqueous chlorine solution flows; Fig. 4 is a graph showing the result of removal of coliform bacteria from the effluent stream as a function of the disinfectant dose; Fig. 5 is a diagram showing the removal of f₂~ percent of wastewater effluent as a function of the disinfection dose; Fig. 6 is a graph showing the removal of coliform bacteria as a percentage of time; Fig. 7 is a diagram showing the removal of f₂~ virus as a percentage of time; Figs. 8, 9 and 10 are diagrams showing disinfection data from operation of existing chlorine disinfection plants modified according to the principles of the present invention; FIG. 11 is a plan view, partially schematic, of the disinfection plant from which the data shown in FIG.

8, 9 and 10 have been obtained; Fig. 12 is a sectional view, on an enlarged scale, of the sump in the plant shown in Fig. 11.

In general, the present invention relates to methods and apparatus for rapid and uniform disinfection of aqueous wastewater, e.g. partially treated wastewater, using a liquid or liquid disinfectant. Suitable disinfectants may be either gases or liquids and include chlorine gas, ozone, chlorine dioxide, and aqueous chlorine, bromine and iodine solutions. Aqueous chlorine solutions, chlorine gas and ozone are preferred disinfectants, and the embodiments of the present invention in which chlorine gas is used are particularly preferred. According to the present invention, the disinfectant and wastewater to be treated continuously pass through a first zone of turbulent mixing, in which the concentration gradient of the disinfectant is rapidly reduced within a short period of time, and the turbulent mixed flow is conducted from the zone of turbulent mixing, whereby a treated waste stream that the flow which has not passed through the zone of turbulent mixing, does not come with this treated sewage stream. According to the present invention, a minimum level of energy loss is maintained in the turbulent mixing zone during disinfection, and at least a minimum amount of energy is used per unit amount of treated wastewater.

As previously stated, the disinfectant and flow to be passed pass through a turbulent mixing zone, in which the disinfectant concentration gradient zone rapidly decreases, obtaining a substantially homogeneous product stream within a limited period of time. Although it is possible to mix for longer periods (over-mix), in this context the level of energy loss should be sufficiently large to achieve this desired level of inhomogeneity within about 1.5 seconds. For a description of the present invention, the mean residence time Θ is defined by the flow and disinfectant in the turbulent mixing zone such as:

wherein V is the volume of the turbulent mixing zone and Q is the velocity of the volume flow of the treated effluent stream.

Under normal operating conditions, the residence time Ö should be 1.5 seconds or less.

It has also been pointed out that at least a minimum energy loss rate in the turbulent mixing zone should be maintained during the process. In this context, a minimum energy loss rate should be maintained; so that in the turbulent mixing zone, a mixing rate T (sec (which can also be referred to as a shear rate) of at least 10 sec, although in some systems with a capacity of over 750 l / min, the mixing speed should be at least 35 sec / sec. with fluid dynamic principles, the mixing rate ΐ is directly proportional to the specific turbulent energy distribution rate δ in the turbulent mixing zone and is inversely proportional to the square of the turbulent

7511341-5 scalar acro layer structure L_e in the turbulent mixing zone: p

<img file="SE430595B_D0001.tif" />

1/3 where k is a constant, which is 0.489 in cgs units.

Inhomogeneity I can be defined as the effective value of the local concentration variations a, of the disinfectant, divided by (the blended) average concentration Δ, and according to hydrodynamic principles, the mixing speed and residence time can also be used to characterize the inhomogeneity of the product stream with respect to the disinfectant in the concentration of the disinfectant. first mixing zone. In the present invention, it is believed that the concentration gradients of the disinfectant are reduced to an almost uniform concentration within a very short residence time, providing a uniform toxic environment for inactivation of organisms before actively and potentially disinfectant losses are obtained. In connection with sowing1⁵ In disinfectants such as chlorine, it is believed that product inhomogeneity is reduced rapidly enough that most potential forms or species of the disinfectant are available throughout the turbulent region, so homogeneously dispersed, that they have high statistical availability for interaction with organisms in the turbulent region over a period of time. period of time before change of chemical form or species of disinfectant occurs due to pH change, reaction with water or reaction with other chemicals or non-biological contaminants.

From practical points of view it has been concluded that lot 2? improved disinfection occurs at mixing speeds of about 10 sec¹ or greater with the corresponding mixing retention time of 1.5 seconds or less. Although measurements have not been performed, for these conditions it is assumed that the product homogeneity is reduced to 0.1 or less.

As indicated, it is also useful to define a mix number θ · τ which mix number is the product of the mixing residence time and the mixing speed, and which characterizes the inhomogeneity of the product stream. Mixing rates of 1.5 - 15 or greater should be applied to achieve superior disinfection results.

For a flow through the continuous mixing system, the specific energy requirement e (the energy consumption per unit of input product stream or the mixing work in the product stream) should be best

7511341-5 at least 39 watts per million liters of processed flow per day (MLD). For a given mixing level, the specific energy demand will increase with increasing mixing layer L_s, but will generally be in the range of 39 - 5Ö0 W / MLD.

The mixing effect applied to a liquid is finally converted to heat due to the viscosity. It can be distributed through mean velocity gradients (similar to the power distribution that occurs in laminar flow), and in the turbulent range through variations in velocity gradients. It is therefore meaningful to distinguish between the total effect distributed per unit mass of fluid and the part that is distributed per unit mass of the fluid over fluctuations in the turbulent velocity. Therefore, in the present specification, the former is defined as the total specific energy distribution degree t_T&gt; while the latter is defined as the specific turbulent energy distribution degree £. The specific total energy distribution rate is defined as:

P pV where P is the net energy loss to the liquid, p is the density of the liquid and V is the volume of the liquid.

The specific turbulent energy distribution degree is defined as

E. - 'We · rp

2ii wherein r, is the intensity of the turbulence.

According to a preferred embodiment of the present invention, an ejector-type mixing system is used in which mixing system obtains the turbulent mixing zone by supplying a drive stream of a smaller portion of the waste liquid to be treated to an induction zone to which the majority of the effluent to be treated. , brought. The drive current is generated by forcing the waste liquid through a suitable nozzle or through another suitable opening. The supply of the driving current to the induction zone causes the waste liquid from the zone to be trapped in this current and to

() Formation of a turbulent flow field in this zone. The thus obtained turbulent mixing zone increases in volume and its cross-sectional area increases along the direction of movement within the induction zone. The best way to add the disinfectant to the turbulent mixing zone is to supply it with the driving current when it is applied to the induction zone. Accordingly, at least a portion of the waste liquid is conducted away from the turbulent mixing zone, thereby obtaining

751 1341-5, a waste stream, while the waste liquid, which did not constitute the original liquid jet or which was not supplied to the turbulent mixing zone, is excluded from this effluent stream, so that substantially all of the waste liquid in the effluent stream comes from the turbulent mixing zone.

Fig. 2 illustrates an apparatus in which various embodiments of the present invention can be performed, and further description of preferred methods is made with reference to the illustrated apparatus. In Fig. 2 is shown a flow line 15, which H1 comprises a cylindrical inlet portion 16 with a diameter D 2, a converging neck 17a, a straight cylindrical mixing line 18 with a diameter D_p and a divergent end lead 17b. A double nozzle 19 is located in, and along the longitudinal axis of, the inlet portion 16 of the conduit 15. The double nozzle 19 comprises a nozzle 21a for fluid of an inner diameter d and a concentrically surrounding nozzle 21b located at the outlet end of the nozzle 21a and having a internal aperture diameter slightly larger than d. An inlet pipe 20 feeds the liquid nozzle 21a and both the nozzle 21a and the disinfection gas line 22 feed the nozzle 21b. In mixing systems that have worked successfully, the aperture diameter d of the nozzle 21b has been proportional to the diameter D_p of the straight mixing line 18, such that the ratio D to d is in the range of 2.5: 1-15: 1 (with the corresponding surface ratio range of 6.25: 1 - 169: 1).

It is convenient that the range of the ratio of the cross-sectional surfaces is 25: 1 - 169: 1 (with the corresponding ratio of the diameters of 5: 1 - 15: 1), which ratio is higher than that commonly used for ejector-type mixing systems. For reasons that will be apparent from the description of the formation and closure of the turbulent mixing zone against the walls of the straight, parallel mixing conduit 18 or the converging throat 17a, the discharge end of the nozzle 21b is at a distance, in the longitudinal direction, from the nearest the end of the straight mixing line 18, which distance is a function of the diameters of the nozzle 21b and the straight mixing line 18. In this context, the mouthpiece piece 21b should most preferably be at an axial distance of 1-2 times D_p from the nearest end of the straight mixing line

18, and most preferably at a distance of about 1.5 D. Similarly, the length of the straight mixing conduit should most preferably be 2-5 times the diameter and particularly suitable is that it is about 5 times as long as the diameter.

1

In operation, a smaller portion of the flow to be processed is pumped through the feed line 20 and forced through the nozzle 21a, producing a jet of waste liquid which also passes into and through the nozzle 21b. On passing through the nozzle 21b, disinfectants, e.g. chlorine gas, in the jet from the nozzle chamber, and the amount of disinfectant so induced can be separately controlled by the amount of waste liquid passing through the nozzle chamber. For vacuum-operated gas chlorination, the disinfecting gas can be fed to the jet of waste liquid at a vacuum of 665-930 Pa, although supply can be made at a lower vacuum, likewise pressure systems can also be used. The jet of liquid waste and the disinfectant supplied forms a driving current starting from the nozzle 21b and supplied to the induction chamber. It has been found that the speeds of the drive current, which are effective, are in the range of 5.2 - 25 m / sec and generally the drive current should have a speed of at least 5.2 m / sec. Accordingly, nozzle 21b emits both chlorine gas and propellant in the form of a relatively high velocity jet to the surrounding flow in the turbulent mixing chamber, whereby a turbulent field and substantially instantaneous mixing of the disinfecting gas with the flow occurs as the gas enters the solution.

The relatively high speed jet, which is a mixture of waste liquid and disinfectant, and which is passed to the turbulent induction chamber gives rise to a conical, very turbulent field, shown by the lines of reference number 23, which field provides thorough mixing (i.e., rapid reduction of concentration gradients of the disinfectant) of the jet constituting the driving stream, the disinfectant and the flow applied to the jet. At the expanded end, the turbulent mixing zone intersects the wall of conduit 15 to obtain a continuous closure of turbulent fluid, which closure prevents the flow which has not passed through the turbulent mixing zone from being prevented from entering the effluent stream, which is passed through it. straight cylindrical mixing line 18.

In FIG. 2 It can be seen that the apparatus is radially symmetrical about its longitudinal axis (except for the conduit of the disinfectant supply line 22), the turbulent mixing zone, hereinafter referred to as mixing cone, likewise has a symmetrical shape from the tip of the outlet end at the nozzle 21 to the bottom of the tube. the circular intersection with the wall of the conduit 15 · The expansion angle α, which is determined by the (extrapolated) tip of the mixing cone, will vary; which variation is a function of the relative velocity of the flow in the mixing chamber, but for slow flow, the expansion angle and generally will be about 14 degrees.

As indicated, a minor portion of the amount of waste liquid to be treated is forced through the nozzle 21b, whereby a drive flow occurs, and the major portion Q₂ of the waste liquid to be treated is fed to the induction zone, into which it is trapped by the turbulent mixing cone. The flow ratios M of the volume velocity Q₂^of the induction flow and the volume rate Q · för for the drive flow, which is within the range 1.4: 1 to 23.1: 1, have been used successfully. Conveniently, the ratio of Q p / Q¹⁵ The average residence time Θ of the apparatus illustrated in Fig. 2 can easily be determined from the volume of the turbulent mixing cone. It can generally be assumed that the waste liquid and disinfectant are mixed to acceptable concentration gradients for the disinfectant when they reach a point near the base of the mixing cone at the intersection with the conduit 15. The volume cone thus defined can be calculated as:

V -_ ₍₅₎ tan (a / 2) wherein D is the diameter of the conduit that intersects the mixing cone at the intersection point, R is the ratio of the cross-sectional area of ​​the opening of the original beam, and the cross-sectional area of ​​the intersecting conduit at the intersection.⁵ and is the angle of expansion of the mixing cone.

The residence time of the apparatus shown in Fig. 2 can be calculated as follows by using Equations (1) and (3), provided that all liquid or gas passing through the mixing cone is conducted.

Θ where M is the ratio

By substituting, you can rewrite the residence time Θ according to:

directly to the effluent stream

V 'Q₁(l + M) and combine equations (4) and

- HRS^{j / 2}__________(You₁) tan (&lt;&gt; 72) (1 + M) R (5)

7511341-5

It is also apparent from these relationships that a desired volume flow ratio M of the trapped flow Q₂ in relation to the drive flow can be obtained by varying a number of factors, both in the physical design and in the operation of the apparatus. It should be noted that the volume of the turbulent mixing cone used in the preferred embodiment of the present process is limited to a maximum of 1.5 times the volume of flow per second of the effluent discharged from the turbulent mixing cone. For ejector-type mixing systems, the present method and apparatus may be characterized by specified ranges of surface ratios R, the drift flow rate u, and the flow ratio M, which may give ΐ or e values, which are outside the previously specified ranges.

According to the present invention, the energy distribution rate should be sufficiently large to obtain a mixing rate. ⁷1 of at least 5 · In this connection, the specific turbulent energy distribution degree ti is generally a function of the applied power P to the driving current:

<img file="SE430595B_D0002.tif" />

wherein η · is the intensity of the turbulence, P is the net power supply from the driving current and p is the density of the liquid or gas, which for water2u containing waste streams is very close to that of water. The factor f is the fraction of the primary effect applied to the mixing zone. Since the layer resistance, which promotes velocity gradients, is minimal in this system, t is very near as great as and is very close to 1. This differs markedly from a pure conduit mixer, 13 C which can amount to only 10-15% of -_m. The specific turbulent energy distribution degree för for the type of apparatus illustrated in Fig. 2 can also be expressed by the angle of expansion cx of the mixing cone, the ratio of the cross-sectional areas R¹¹¹ point of intersection and closure with the walls of line 15:

£ = 3 tan (a / 2) (u / D) “n

The scalar macro layer L for a system, e.g. as illustrated in Fig. 2 can be approximated to about 0.131 D for calculating the design of the equipment, and by combining the equations and (7) it is obtained that the mixing speed "of such a system can be expressed as:

7511341-5

T^-1 = 1.36 [fR 3/2] ^1/3 (u / D)

- R

By disinfecting waste solution with gaseous chlorine as a disinfectant according to the present invention, compatible and reliable bacterial killing of over 99.9% measured for the removal of fecal coliform bacteria and greater killing rate of virus than 99% measured for fp virus can be achieved. of seconds (eg 3 seconds). Such a chlorine gas result may be at least partially due to the rate at which dissolved Clp mixes with the entire waste stream relative to the rate at which aqueous chlorine reacts according to undesirable side reactions with waste stream components, e.g. nitrogenous materials.

It is also known that one can expect gaseous chlorine to dissolve very quickly and that the pH of the waste stream is generally such that substantially no dissolved Cl₉ (as opposed to hypochlorite ions) are present at equilibrium under normal conditions. In this context, it is also considered that the gaseous chlorine supplied to the turbulent zone of the flow in the form of fine, highly dispersed bubbles results in transfer to solution and mixing of dissolved Clp sufficiently rapidly to expose the flow in the turbulent zone to chlorine in the form. of Clp.

Regardless of whether the explanations stated are accurate or not, the fact that treatment of chlorine waste streams under the hydrodynamic mixing conditions of the present invention provides significantly better disinfection performance and reduces the time required to achieve any stated reduction of bacteria and viruses. Nevertheless, it is believed that it is important to exclude the waste liquid which has not passed through the first mixing zone from the outlet stream of the system. Accordingly, only waste liquid thoroughly mixed with disinfectant within a limited period of time after disinfectant application is removed through the system's outlet line, minimizing the detrimental effect of undesirable side reactions and optimizing the efficiency of the system. In connection with the embodiment described in connection with the apparatus of FIG.

2, it is pointed out that the expanding turbulent mixing cone cuts the interfaces of conduit 15, whereby a continuous turbulent closure which prevents waste liquid not contained in the mixing cone from passing through the turbulent closure.

751 1341-5

In this regard, the turbulent effects of the intersection of the mixing cone are large enough to interrupt any significant area of ​​laminar flow adjacent the wall of conduit 15 into the region of the turbulent slope. For the training and maintenance of such a turbulent closure, the geometry of the system and power supply to the drive current should be such that enough turbulent energy remains in the turbulent mixing cone by the time it reaches the point of cutoff with the conduit wall of the effluent stream. such closure can be designed. In operation, it is a desirable feature of the present process that a constant flow rate drive flow through the nozzle 21a (e.g. using a pump that pumps constant volume) can be maintained while the rate of the waste liquid being induced to the mixing cone. and the volume velocity of the effluent may vary within a wide range according to the variations in the discharge of waste liquid for disinfection to the induction chamber. The geometry of the system, including the location of the nozzle 21b, may be such that the intersection of the mixing cone with the conduit 15 will be at the nearest end of the straight conduit mixing conduit 18 for flow rates being processed. At the same speed of the drive flow and less total processing speeds, the closure of the mixing cone will be along the surface of the converging neck 17a of the conduit 15, and for larger total processing speeds, the extended straight mixing conduit 18 allows the closure of the mixing cone to be maintained in places downstream. the converging neck of the cord. If the nozzle is inappropriately positioned relative to the interface intended to form the intersection with the mixing cone, or if the power supply to the drive stream of the waste is not large enough to give sufficient energy-rich cutting, a suitable closure will not be obtained and flows with high biological values ​​will penetrate the straight mixing line and follow the system's effluent flow. In addition, in connection with this later, according to fluid dynamic principles with regard to mixing.

5. ' It is desirable to operate the system so that the intensity of turbulence 7 and the fraction of primary distributed power F approaches 1, so that the total energy supply approaches or becomes turbulent. To achieve this, the system can be operated with low or no pressure recovery to the effluent flow from the drive.¹¹ the flow (e.g., the outlet pressure should at best be approximately equal to the body pressure of the mixing system), since this pressure recovery is a measure of (1F) P.

In order to provide and maintain an effective slope, it is desirable that the boundary, which is cut off by the mixing cone, have a shape that minimizes formation of a laminar boundary layer of potentially non-disinfected flow adjacent the surface. It has been found that even at very smooth interfaces, e.g. those contained in fiberglass reinforced polyester tubes give excellent results when operated under specified conditions. However, formation of an effective closure and interruption of laminar flow can be enhanced by protruding surfaces or projected surfaces at the cutting surface, e.g. as a series of protruding rings, which interrupt the flow adjacent to the surface. It should of course be borne in mind that the intensity of turbulence decreases as a turbulent field approaches and a fixed surface and deviation from isotropy occurs. For an effective closure, it is believed that the intensity of the turbulence should be about 0.1 or greater at a distance of 0.1 D from the solid surface.

Fig. 3 illustrates a mixing device 25a, which is especially adapted for treating municipal wastewater or streams with aqueous chlorine solutions. The illustrated device 0 comprises an inner nozzle 25 which is coaxial with an outer nozzle 26. The latter is screwed into a housing 27, forming a tapered neck 28 and a tubular straight mixing line 29. The primary waste drive flow is supplied to the inner nozzle 25 through an inlet 30, while an aqueous chlorine solution is supplied to the inner nozzle 25 by means of a conduit 31. An secondary waste liquid is supplied to an induction zone through an inlet 32 ​​whose shaft is at right angles to the shaft. for the nozzles 25 and 26.

When the primary waste propellant flow is forced through the inner nozzle 25 under considerable pressure, it comes into contact, at a significant rate, with the aqueous chlorine solution supplied to the nozzle 26, and it draws chlorine solution before leaving the outer nozzle 26. The flow rate of the aqueous chlorine solution can be controlled independently of the flow rate of the propellant flow, and will be relatively small in relation to the velocity of the propellant flow and also in relation to the total treated flow rate. For example, conventional aqueous chlorine solutions for disinfection treatment of municipal wastewater may have concentrations of 300-3000 mg / l and at typical treatment doses of in 2 mg / l, the flow rate of the chlorine disinfection medium will be 2.6 liters per minute (LPM) to about 26 LPM for a system with a drive flow rate of 45¹) LPM and a total flow of 3785 LPM. The primary waste stream and the aqueous chlorine stream flow from the nozzle 26 into the turbulent induction zone, where additional waste liquid is induced to the liquid jet, a highly turbulent cone-shaped continuously expanding mixing cone 26a intersecting the adjacent mixing end of the adjacent end. Waste streams that have not passed through the mixing cone are excluded from the product stream, which flows through the straight mixing conduit 29 and leaves it at the far end. Although using aqueous chlorine solution under the same operating conditions is less effective than chlorine gas, the mixing system illustrated in FIG. 3, nevertheless, have significant advantages over conventional disinfection systems in which an aqueous chlorine solution is used as a treating agent. When using aqueous chlorine solution as a disinfectant, it is preferred that the disinfectant has a pH of less than 5 and particularly suitable is that the pH is 3 or less. Although the acidity of the disinfectant solution has little effect on the pH of the treated effluent, it will change the equilibrium of the disinfectants so that higher concentrations of lethal Cl₂and HOC1 occurs. At rapid mixing, it is believed that some of the benefits of this increasing concentration of lethal compounds are obtained before equilibrium conditions are reached due to the higher pH value of the mixed product stream.

A large amount of experimental data was obtained during experiments carried out on the second flow from a biological purification plant using a test mixer, chlorine (G) and aqueous chlorine which obtained successful results.

Flow rate M

Diameter ratio D / d Speed ​​of the driving current Mixing speed

Residence time Mixing number θτ ¹

Specific energy requirements e Total throughput

There was a marked difference here which was alternately fed with gas (A). The variable range, at, was the following:

1,4:1 - 23,1:1

2,5:1 - 13:1

5.2 - 25 m / sec

77-1 98.6 - 503 sec¹0.014 - 0.346 sec

1,51 - 10,85

2.1 - 1150 W / MLD maximum 151 LPM in disinfection speed, total kill and the amount of chlorine required. Figures 4 and 5 show

7511341-5 percent removal of the total amount of coli-formed bacteria and fp virus as a function of the disinfectant dose. Fig. 4 shows that substantially complete removal of bacteria is achieved at a dosage of only 4 mg / l of gaseous chlorine, while a dose of greater than 16 mg / l is required to effect the same killing with the aqueous solution. The reduction of the total amount of chlorine required when gaseous chlorine is used in accordance with the present invention to achieve a substantially complete killing of coliform bacteria from the waste liquid constitutes a substantial saving of material. This is accompanied by the preparation of a sewage solution which has significantly lower chlorine content (residual chlorine) than is usually achieved, and is therefore less toxic to water life.

Removal of fp virus is even more significant, as shown in FIG.

5th It is a well-known fact that disinfection systems in which chlorine is used have previously been very ineffective in killing viruses.

Usually only a slight reduction in the amount of virus is obtained in a chlorine contact chamber. The kill obtained from both aqueous and gaseous chlorine shown in Fig. 5 is superior to that obtained in commercially available chlorine disinfection systems. -^u The improved mixing conditions of the present invention make the killing of chlorine virus as good or better than conventional ozone treatment methods, an agent known for its anticancer activity. Of course, the virus-killing properties of ozone can in turn be used in the present process by -⁵ use of ozone as a liquid disinfectant.

Figures 6 and 7 show the killing of coliform bacteria and viruses measured according to standard methods for examining water and wastewater as a function of time, with dosage levels of 17 mg / l in each case. As can be seen from these two diagrams, the present invention provides extremely high kill rates, and provides a 99 percent or higher kill of fp virus within a few seconds or less (killing occurred as quickly as survey customers are performing).

In addition to the performance of disinfection in accordance with the present invention with respect to improved bacterial and viral killing, which is of course important with regard to health and ecological views, the present invention provides a number of additional advantages. In particular, the present invention can be used to eliminate the need for the contact chamber commonly used in conventional^II chlorination systems, e.g. the one illustrated in Fig. 1. The chamber

751 1 3 4 1-5

10, which may consist of a large, compact, uncovered structure, comprises a pair of parallel baffles 11 and 12 which together with the vertical side walls of the chamber limit a curvilinear flow path for the waste solution to be treated. The waste stream is introduced into the contact chamber 10 through an inlet 13a and an aqueous chlorine solution is supplied to the contact chamber through a second, proximate lead 14. The mixture of the aqueous chlorine solution and the waste is moved within the contact chamber around the baffles 11 and 12 and finally flows out through the outlet 13b. The residence time of the flow in such a system typically varies within the range of 15-30 minutes.

Contact chambers not only involve capital costs, but also involve the use of a significant amount of land area, which, depending on the size of the chlorination system, its location and the use to which the land used can be better used, can be used profitably, can be an extremely important factor . In addition, the present invention reduces the total cost of disinfecting a given amount of wastewater. Inextricably linked to a conventional contact chamber for a disinfection system are the installation costs involved in the construction of the chamber and the energy consumption to produce and pump the aqueous chlorine solution to the contact chamber.

Fig. 11 shows a contact chamber disinfection plant similar to that illustrated in Fig. 1. The embodiment of Fig. 11 schematically illustrates the contact chamber used in the active sludge decontamination plant in Prophetstown, Illinois, USA. A difference between the contact chamber shown in FIG.

11, and the one in Prophetstown is in the number of channels used. The contact chamber in Prophetstown comprises only a single channel, while the contact chamber shown in Figure 11 comprises 3 channels. However, for the function, the two channels are identical and the contact chamber of Figure 11 has been illustrated with three channels only because it corresponds to the previously known contact chamber of Figure 1.

Initially, the contact chamber in Prophetstown included a waste liquid inlet as shown at 13a in Figure 1, an outlet as shown at 13b, and an inlet tube as shown at 14a. More recently, however, the contact chamber has been modified to conform to that shown in Figure 11, in which chamber the principles of the present invention are applied.

11 As shown in Figs. 11 and 12, the contact chamber, which comprises

7511341-5 is designated by reference numeral 110, an inlet 113a for waste liquid and an outlet 113b for waste liquid. A sump 130 has been formed at the end of the inlet of the contact chamber 110 and a partition jsi has been added to partially delimit the sump 130.

Inside the sump 130 is a conduit 115 similar to conduit 15 of Fig. 1. A multiple nozzle 119 is axially aligned with conduit 115; to the inner nozzle of the multiple nozzle 119, a flow is pressurized by means of a submersible pump 132 via a conduit 33, and to its outer nozzle, gaseous chlorine 10 is passed through a conduit tube 122. A vertical rod 34 extends through a flange 36 provided on the pump 152 to facilitate placement and resetting of the pump and multiple nozzle.

An adjustable control valve 37 is attached to the chlorine gas supply line 122 for controlling the chlorine gas flow to the multiple nozzle 15 119. Co-current conduit 115 (and preferably near the waste liquid outlet 113b) is provided with a sensor or probe 38, the purpose of which is to produce a signal that changes. with the variations of residual chlorine level in the waste stream leaving the contact chamber 110.

Probe 38 and control valve 37 are electrically interconnected over an analyzer 39 so that the analyzer 39 can be set to control the flow of chlorine gas to the nozzle 119 so that a predetermined level of residual chlorine is present in the flow leaving the contact chamber 110.

In addition, the control system can be used to measure a suitable flow of a disinfectant, e.g. SC 2, to the disinfected flow to eliminate any residual chlorine.

Experiments were carried out with the contact chamber in Prophetstown, as it appeared prior to the modification (mainly as shown in Fig. 1) using chlorine gas co-disinfectant in the manner previously used. In this regard, the chlorine gas was atomized directly to the waste liquid at the feed end of the contact chamber.

Experiments were also carried out after the contact chamber had been modified according to the principles of the present invention. The results of these experiments are illustrated in Figures 8, 9 and 10.

The last-mentioned figures, which compare the effectiveness of the disinfection in the Prophetstown contact chamber, both before and after modification, show significant improvements in efficiency resulting from the practice of the present invention. Not only did the number of fecal coliform bacteria have significantly decreased in both the percentage kill and actual kill, but this

Furthermore, disinfection had been carried out with smaller doses of chlorine. The removal of fecal streptococci was also markedly improved as a result of the present invention.

The following Table I also includes data relating to the enlargement of the disinfection plant in Prophetstown by application of the present invention.

TABLE I

Fecal coliform bacteria

<td>In ---------------------------- Γ^; trial |</td><td>Before</td><td>1 1 In After</td><td>not dead</td><td>Dosage</td><td> 1-------------------_rResidual chlorine!</td>

<td>date</td><td>No. / 100 ml</td><td>No. / 100 ml</td><td>up</td><td>(Mg / 1)</td><td>(mg / l); 4</td>

<td> , 1 22-4-74</td><td> 320.000</td><td> 40</td><td> 99,98</td><td> 3,1</td><td> 0,95</td>

<td> 24-4-74</td><td> 25.000</td><td> 0</td><td> 100,00</td><td> 2,3</td><td> 0,85</td>

<td> 01-5-74 '</td><td> 350.000</td><td>38 °</td><td> 99,89</td><td> 5,3</td><td> 1,40</td>

<td> 04-6-74</td><td> 330.000</td><td> 15</td><td> 99,99</td><td> 3,75</td><td> 0,60</td>

<td> 19-6-74</td><td> 290.000</td><td> 0</td><td> 100,00</td><td> 2,83</td><td> 0,52</td>

<td> 16-7-74</td><td> 150.000</td><td> 250</td><td> 99,83</td><td> 1,31</td><td> 0,60</td>

<td> 30-7-74</td><td>I.26O.OOO</td><td> 45</td><td> 99,99</td><td> 2,77</td><td> 2,75</td>

<td> 31-7-74</td><td> 660.000</td><td> 0</td><td> 100,00</td><td> 2,80</td><td> 0,40</td>

<td> 06-8-74</td><td> 650.000</td><td> 320</td><td> 99,95</td><td> 1,18</td><td> 0,18</td>

<td> 13-8-74</td><td> 820.000</td><td> 160</td><td> 99,98</td><td> 2,30</td><td> 0,27</td>

<td> 15-8-74</td><td> 110.000</td><td> 0</td><td> 100,00</td><td> 1,18</td><td> 0,80</td>

<td> 20-8-74</td><td> 200.000</td><td> 4</td><td> 99,998</td><td> 1,73</td><td> 1,30</td>

<td> 22-8-74</td><td> 120.000</td><td> 180</td><td> 99,85</td><td> 1,18</td><td> 0,21</td>

<td> 04-9-74</td><td> 280.000</td><td> 0</td><td> 100,00</td><td> 5,28</td><td> 3,50</td>

<td>averaging</td><td> 400.000</td><td> 100</td><td> 99,96</td><td> 2,50</td><td> 1,02</td>

The following Table II provides characteristic data for the waste flow.

7511341-5

HH ω tn &lt;

bD C • Η

C bD bC o r — IC tö W bC C • H

C φ p

CO c 5 o +5 to P Φ • C P. on CL

H • H&gt;

C Φ Ό k xd&gt; I — i

Φ * d

Φ E cd bO • H rH 4-&gt; cd C coj S

<td></td><td></td><td></td><td>in</td><td>XT</td>

<td></td><td></td><td>m</td><td>OH</td><td>tn</td>

<td></td><td>cn</td><td> «</td><td>α</td><td>Λ</td>

<td></td><td>P.</td><td>b</td><td>FR</td><td>FR</td>

<td></td><td>z 1</td><td>ro</td><td>t</td><td>VO</td>

<td></td><td></td><td>O</td><td>o&gt;</td><td>vivo</td>

<td></td><td>X</td><td> **</td><td> *»</td><td></td>

<td></td><td>z</td><td>t</td><td>σ&gt;</td><td>XT</td>

<td></td><td></td><td></td><td></td><td>R-I</td>

<td></td><td>CD .p z- &lt;k</td><td></td><td></td><td></td>

<td> •</td><td>ω ·</td><td></td><td></td><td></td>

<td>rH</td><td>tö&gt;</td><td></td><td></td><td></td>

<td>T3</td><td>&lt;M p</td><td>O</td><td></td><td>OH</td>

<td>c</td><td>• C &lt;u</td><td>rH</td><td>CO</td><td>rH</td>

<td>CD</td><td>ίΧ Φ -P</td><td> 1</td><td> 1</td><td> 1</td>

<td></td><td>to cc</td><td>ΧΓ</td><td>cow</td><td>in</td>

<td>Φ</td><td>3 Ε · Η</td><td>rH</td><td>OH</td><td>in</td>

<td> ¢)</td><td>w aö</td><td></td><td></td><td></td>

<td></td><td>cd P&gt;</td><td></td><td></td><td></td>

<td> •</td><td> 10 ·</td><td></td><td></td><td></td>

<td>rH</td><td>tö&gt;</td><td></td><td></td><td></td>

<td>Tj</td><td>4-i H</td><td></td><td></td><td></td>

<td>c</td><td>• C Φ</td><td>OH</td><td>CO</td><td>in</td>

<td>CD</td><td>P. Φ Ό</td><td>rH</td><td></td><td>OH</td>

<td>Λ</td><td>to C φ</td><td></td><td></td><td></td>

<td>Φ</td><td>SES</td><td></td><td></td><td></td>

<td>tn</td><td>CO KÖ</td><td></td><td></td><td></td>

<td></td><td>Cd rH</td><td></td><td></td><td></td>

<td> •</td><td>-P rH</td><td></td><td></td><td></td>

<td>rH</td><td>CO cö</td><td></td><td></td><td></td>

<td>TJ</td><td>CO</td><td>O</td><td>vivo</td><td>OH</td>

<td>C</td><td>Cm P</td><td>VO</td><td>m</td><td>in</td>

<td>CD</td><td>• C Φ</td><td>rH</td><td>rH</td><td>rH</td>

<td></td><td>Φι Φ 4J</td><td> 1</td><td>IN</td><td>J</td>

<td>Φ</td><td>co CC</td><td>O</td><td>OH</td><td>XT</td>

<td>x&gt;</td><td>3 E-rl</td><td>0J</td><td> 00</td><td>O</td>

<td>O</td><td>CO queue</td><td>OH</td><td>rH</td><td>m</td>

<td></td><td>CD</td><td></td><td></td><td></td>

<td> •</td><td>P</td><td></td><td></td><td></td>

<td>rH</td><td>ω *</td><td></td><td></td><td></td>

<td>τ)</td><td>cö&gt;</td><td></td><td></td><td></td>

<td>C</td><td>&lt;W rH</td><td>O</td><td>VO</td><td>vivo</td>

<td>CD</td><td>• C Φ</td><td>rH</td><td>ΓΟ</td><td>O</td>

<td>Λ</td><td>p. Φ TÖ</td><td>OH</td><td>rH</td><td>OH</td>

<td>Φ</td><td>CO C Φ</td><td></td><td></td><td></td>

<td>X)</td><td>SEE</td><td></td><td></td><td></td>

<td>O</td><td>'to KÖ'-'</td><td></td><td></td><td></td>

<td></td><td></td><td></td><td></td><td></td>

<td>rH</td><td> •</td><td></td><td></td><td></td>

<td>Ό</td><td> &gt;</td><td></td><td></td><td></td>

<td>C</td><td>ρ</td><td></td><td>XT</td><td>VO</td>

<td>CD</td><td>CO Φ</td><td>IN</td><td>rH</td><td>rH</td>

<td>r</td><td>tn -p</td><td></td><td> 1</td><td> 1</td>

<td>Φ</td><td>c</td><td></td><td>O</td><td>VO</td>

<td>ίΏ</td><td>•HRS</td><td></td><td>XT</td><td>OH</td>

<td> —</td><td>s' · ''. ---- ...</td><td> — .</td><td></td><td></td>

<td></td><td> •</td><td></td><td></td><td></td>

<td>r-1</td><td> &gt;</td><td></td><td></td><td></td>

<td>Ό</td><td>rH</td><td></td><td></td><td></td>

<td>c</td><td>Φ</td><td></td><td></td><td></td>

<td>CD</td><td>CO Ό</td><td> |</td><td>tn</td><td>O</td>

<td>C</td><td>oa &lt;u</td><td></td><td>OH</td><td>OH</td>

<td>Φ</td><td>E</td><td></td><td></td><td></td>

<td>OH</td><td> '—</td><td></td><td></td><td></td>

<td></td><td></td><td></td><td></td><td></td>

<td>rH</td><td> •</td><td></td><td></td><td></td>

<td>Ό</td><td> &gt;</td><td>O</td><td></td><td> 00</td>

<td>C</td><td>ρ</td><td>b</td><td>O</td><td>co</td>

<td>d</td><td>CO Φ</td><td>rH</td><td>CO</td><td>r</td>

<td>n</td><td>tn -p</td><td></td><td> 1</td><td> 1</td>

<td>Φ</td><td>c</td><td>O</td><td>O</td><td>O</td>

<td>yes</td><td></td><td>σ \</td><td>VO</td><td>OH</td>

<td>O</td><td></td><td>rH</td><td>rH</td><td>0J</td>

<td></td><td></td><td></td><td></td><td></td>

<td>rH</td><td></td><td></td><td></td><td></td>

<td></td><td> &gt;</td><td></td><td></td><td></td>

<td>c</td><td>rH</td><td>O</td><td>FR</td><td>m</td>

<td>CD</td><td>CO Φ</td><td>CO</td><td>rH</td><td>vivo</td>

<td>n</td><td>CQ Ό</td><td>rH</td><td>rH</td><td>rH</td>

<td>Φ</td><td>Φ</td><td></td><td></td><td></td>

<td>xa</td><td>E</td><td></td><td></td><td></td>

<td rowspan="2">O</td><td>v_z</td><td></td><td></td><td></td>

<td></td><td></td><td></td><td>•HRS</td>

<td></td><td></td><td></td><td></td><td>-P</td>

<td></td><td>Ό</td><td></td><td></td><td>ω</td>

<td></td><td>CD</td><td>•HRS</td><td>•HRS</td><td> 3</td>

<td></td><td>c</td><td>c</td><td> 1—1</td><td>hO</td>

<td></td><td></td><td> 3</td><td> 3</td><td> 3</td>

<td></td><td></td><td>• R 3</td><td>• m</td><td>CD</td>

<td></td><td></td><td></td><td></td><td></td>

O tn * »fro ft VO

CO

In rH Oi

<img file="SE430595B_D0003.tif" />

oo LO rH

I OJ XT OJ rH OJ o \

IN

ΟΛ

<img file="SE430595B_D0004.tif" />

o vo rH

IN

O rH OJ

O 00

I £

Φ -P

Φ φ W n

<img file="SE430595B_D0005.tif" />

<img file="SE430595B_D0006.tif" />

<img file="SE430595B_D0007.tif" />

<img file="SE430595B_D0008.tif" />

A i

<img file="SE430595B_D0009.tif" />

In Table I, the column with the heading before the actual number of faecal coliform bacteria refers to 100 ml of waste liquid when this liquid enters the modified disinfection plant. The column with the heading indicates the actual number of faecal coliform bacteria in the waste liquid when it leaves the modified disinfection system. Accordingly, Table I not only shows a significant reduction in the actual number of fecal coliform bacteria per milliliter of waste liquid, as it emerges when leaving the contact chamber, but also shows a significant increase in the percentage kill, although smaller doses are used and despite significantly less residual chlorine content. From the column entitled Dosage, it is appreciated by those skilled in the art that the dose used in conventional contact chambers when using aqueous chlorine is typically 5-10 mg / l and is often as high as 15-20 mg / l. The range of variables successfully studied in the Prophetstown facility are as follows:

Flow rate M

Diameter ratio D / d

Drive current velocity u

Mixing speed τ '¹

Residence time Θ

Mix number θτ ~ 1

Specific energy requirements e

Total throughput

- 6

9,8

9.8 m / s

10.9 sec^-1

1.19 - 0.71 sec

- 7,7

136 - 272 W / MLD

760 - 1900 LPM

It is to be understood that the present invention also envisages the use of more than one conduit with piston flow and nozzle if the flow rate of the waste solution is sufficiently large. In Figs. 11 and 12, a plurality of pistons flow and multiple nozzles 119 may be provided in the sump 30 to accommodate larger systems with greater flow rates for the waste liquid. Each of the many nozzles can be provided with a separate conduit mixing conduit, or more than one nozzle may be directed to a conduit mixing conduit, such that the cone cones intersect either a fixed interface or each other, thereby providing a closure. In addition, pipes and nozzles of non-circular cross-section can be used, and the flow can leave the turbulent mixing zone through more than one outlet.

In a larger purification plant for the treatment of several million liters per day, four units, as shown in Fig. 11, were unp'10 placed parallel to the dividing wall in one half of a double channel cone. The four multiple nozzles were fed with a single pump. The other half of the basin was left unmodified so that a simultaneous comparison could be made. Chlorine gas was fed directly to the nozzles of the modified system, as described above. The conventional gas distribution and measurement system was left intact so that the conventional system was fed with an aqueous chlorine solution commonly used.

The following disinfection results were obtained.

TABLE III

Fecal coliform bacteria

Conventional in relation to modified Ten Minutes channel contact time

<td>[Experimental</td><td>| Before I</td><td>After |</td><td>% dead</td><td>After</td><td>1 deceased-l</td><td>Dose</td>

<td>date</td><td>No. 100 ml</td><td>conventional '</td><td>up</td><td>modified</td><td>ning &lt;</td><td>mg / 1</td>

<td></td><td> !</td><td>nell I</td><td></td><td>No. / 100 ml</td><td></td><td></td>

<td></td><td> •</td><td>No. / 100 ml!</td><td></td><td></td><td></td><td></td>

<td> 10-3-75</td><td>^: 373.000</td><td> 2.340</td><td> 99,37 :</td><td> 166</td><td> 99,96</td><td> 1,54</td>

<td> 11-3-75</td><td> | 247.000</td><td> 1.740</td><td> 99,30 _;</td><td> 100</td><td> 99,96</td><td> 1,61</td>

<td> 12-3-75</td><td> * 137.000</td><td> 2.140</td><td> 98,44</td><td> 60</td><td> 99,96</td><td> 1,55</td>

<td> 13-3-75</td><td>I 57,000</td><td> 340</td><td> 99,40</td><td> 52</td><td> 99,91</td><td> 1,61</td>

<td> 17-3-75</td><td> 66.000</td><td> 320</td><td> 99,82</td><td> 78</td><td> 99,88</td><td> 1,48</td>

<td> 18-3-75</td><td> 86.700</td><td> 620</td><td> 99,28 ,</td><td> 91</td><td> 99,90</td><td> 1,34</td>

<td>averaging</td><td> 161.200</td><td> 1.250</td><td> 99,22 </td><td> 91</td><td> 99,94</td><td> 1,52</td>

<img file="SE430595B_D0010.tif" />

<img file="SE430595B_D0011.tif" />

<img file="SE430595B_D0012.tif" />