Super oxidation, coagulation and flocculation system for treatment of water and wastewater

The super oxidation, coagulation and flocculation system is applicable to water and wastewater chemical treatment in which oxidation, coagulation and flocculation processes take place in a single vessel.The apparatus and process can be used for treatment of domestic and industrial water and wastewater for removal of organic and inorganic contaminants.The oxidation process can be provided by several oxidizing chemicals such as ozone, hydrogen peroxide, potassium permanganate, chlorine and Ultra Violet Lights, and the coagulation process can be accomplished with several coagulants such as aluminum sulphide, ferric chloride, ferric sulphate.Selection of the chemicals depends on the quality of the water or wastewater to be treated and the treated water quality required, and it covers a wide range of impurities to be removed and specifically difficult to oxidize hydrocarbons and chlorinated organics, and iron, manganese, uranium, arsenic, cyanide, hydrogen sulphide.The apparatus and the process are economical and have a small installation footprint as several processes take place in a single vessel.

FIELD OF THE INVENTION

The invention relates to a process and apparatus for chemical treatment of water and wastewater with oxidation, combined with coagulation and flocculation processes.

BACKGROUND OF THE INVENTION

A variety of water and wastewater treatment systems involving oxidation, coagulation and flocculation processes require several vessels, large foot print, and complex mechanical, electrical and instrumentation control systems.

The super oxidation system with ozonation involves high pressure ozonators which are expensive and not safe to operate due to the ozone being supplied under a high pressure. The ozone and water mixing takes place in an ozonation vessel and the ozone is dispersed in the vessel through diffusers which have very small pores to produce very small ozonated air bubbles. The diffusers are subject to plugging with water or wastewater precipitates and are difficult and costly to replace, and the diffuser replacement requires a shut down of the oxidation system.

The efficiency of the ozone solution in the water or wastewater is dependent mainly on the ozonated air bubble size and the height of the ozonation vessel.

The smaller the ozonated air bubbles and the higher the ozonation vessel, the higher the ozone solution in the water or wastewater.

The present invention employs a different process and device for mixing water with ozone which primarily takes place outside of the ozonation vessel. The present invention can employ multiple ozone and water mixing systems which facilitate maintenance, replacement and repairs without shutting down the oxidation system. Also, the multiple ozone and water mixing systems are suitable to varying flow rates and quality of the inlet water.

The present invention ensures a superior mixing of ozone and water and the efficiency of the ozone solution in water is not dependent on the ozonation vessel height. The present invention employs vacuum type ozone generators which are less expensive and safer to operate than the pressure type ozone generators.

BRIEF SUMMARY OF THE INVENTION

The treatment system of the present invention is a process and apparatus for chemical treatment of water and wastewater containing inorganic and organic contaminants such as dissolved iron, manganese, arsenic, uranium, cyanide, hydrogen sulphide, naturally occurring organics, hydrocarbons and chlorinated organics.

The treatment system is specifically suited for removal of difficult to oxidize and remove organics, hydrocarbons and chlorinated organic compounds.

The treatment system can be operated as a super oxidation process alone or in combination with coagulation and flocculation processes accomplished in the same vessel as shown onFIG. 1andFIG. 2.

The treatment system as shown onFIG. 1comprises the following major components:Raw water inlet piping.Oxidation system with ozonation alone or ozonation with hydrogen peroxide.Oxidation, coagulation and flocculation vessel.Coagulation and flocculation system.Treated water outlet piping and off gas discharge piping.

The treatment system can be supplemented with other treatment processes including settling, dissolved air flotation and/or filtration.

The inlet water piping system is located at the bottom of the oxidation vessel and it preferably includes a strainer with an automatic flushing system, to remove coarse suspended solids of approximately 2 mmØ and larger, and a flow meter to monitor the inlet water flow rate and volume, and to pace dosage of oxidizing chemicals such as ozone and hydrogen peroxide, and a coagulation chemical, if required.

The oxidation system comprises a recirculation pump, an ozone supply system c/w J. K. patented air aspirator-mixer, hydrogen peroxide supply and mixing system c/w an in-line mixing chamber for mixing the inlet water with hydrogen peroxide before the inlet water and hydrogen peroxide are mixed with ozone in the air aspirator-mixer.

The oxidation recirculation pump flow rate is preferably approximately equal, within 10-20%, of the inlet raw water flow rate, although higher and lower recirculation flow rates can be used.

The oxidation vessel is vertical and preferably round or square or rectangular in horizontal cross section and having a height of preferably three to five times the largest cross section dimension, and fixed bottom base, and removable top cover and air tight construction of corrosion resistant materials.

The treated water outlet piping is located at the top of the oxidation vessel and it is arranged such to maintain a designated water level in the vessel and to prevent the ozone off gas escaping into the atmosphere, by-passing an ozone destruction unit.

The ozone off gas discharge system comprises piping which collects the ozone off gas from the top of the oxidation vessel and from the treated water outlet piping, and an ozone destruction unit, and an air outlet piping to the atmosphere.

The ozone off gas can be recycled to the air aspirator-mixer before it passes through the ozone destruct unit.

The coagulation system comprises a recirculation pump, a coagulant supply system, an initial, a low hydraulic gradient mixing vessel and a high hydraulic gradient static mixer for mixing the coagulant with the water, and inlet and outlet piping system which connects the coagulation system with the oxidation vessel.

The coagulation recirculation pump flow rate is preferably the same or within 10 to 20%±of the inlet raw water flow rate.

The treatment system as shown onFIG. 2is an economic and compact revision of the system shown onFIG. 1and it comprises the same major components of the raw water inlet piping, the oxidation vessel and the treated water outlet piping and the off gas discharge piping.

The oxidation and coagulation systems are combined together and they are accomplished by means of the same recirculation pump by splitting the pump discharge flow into two separate oxidation and coagulation streams.

The recirculation pump flow rate is approximately twice the inlet raw water flow rate and the oxidation and coagulation streams flow rates are approximately equal.

DETAILED DESCRIPTION OF THE INVENTION

According to the embodiment of the invention, as shown onFIG. 1, the treatment system comprises the following major components: a raw water inlet piping1, an oxidation system7, an oxidation, coagulation and flocculation vessel19, a treated water outlet and off gas discharge piping26, a coagulation and flocculation system37.

The raw water inlet piping1, comprises a raw water inlet pipe2, a strainer3with an automatic flushing valve4, a flow meter5and a discharge pipe6. The discharge pipe6is preferably slotted or perforated to provide a uniform distribution of the wastewater in the oxidation vessel19.

The oxidation system7comprises an oxidation recirculation pump8, an initial chemical mixing chamber9, an air (ozone) aspirator-mixer10, an inlet pipe11, and outlet pipe12, a discharge pipe13, an ozone generator15and a hydrogen peroxide or other chemical supply18.

Preferably the ozone generator15is provided with an ozone in water monitor16and an ozone in water sensor17.

The oxidation recirculation pump8takes water from the raw water inlet piping1, and pumps the raw water through the chemical mixing chamber8, the air (ozone) aspirator-mixer10, into the outlet pipe12and the discharge pipe13.

The air (ozone) aspirator-mixer10, aspires ozonated air from the ozone generator15when the recirculation pump8pumps the raw water through the air (ozone) aspirator-mixer10.

The recirculation pump8inlet pipe11connection to the raw water inlet pipe2and the raw water outlet pipe6eliminates a need for a precise control and adjustment of the recirculation pump8flow rate to match the raw water inlet flow rate.

The raw water can flow from the raw water inlet pipe2into the recirculation pump8and into the oxidation vessel19and the water can flow into the circulation pump8from the raw water inlet pipe2and from the oxidation vessel19in various proportions to satisfy the recirculation pump8flow rate.

The chemical mixing chamber9is provided to thoroughly mix hydrogen peroxide, or other oxidizing chemical, with the raw water before the mixture is mixed with ozone.

The chemical supply18is connected upstream of the initial chemical mixing chamber9.

The ozone in water monitor16and the ozone in water sensor17are provided to adjust the ozone dosage from the ozone generator15in order to maintain a desired ozone residual in the treated water before it leaves the treatment system.

The oxidation and coagulation and flocculation vessel19comprises a cylindrical or square or rectangular shell20, a fixed bottom cover21, and a removable top cover22which provides access to the vessel for installation, inspection and repairs of the components contained inside the vessel19.

The vessel19functions as an oxidation vessel in its lower part23and a flocculation vessel in its upper part24.

The treated water outlet and off gas discharge piping26comprises a treated water outlet inside pipe27which is preferably perforated or slotted on the top, an outlet outside pipe28, vent pipes29&30, a siphon breaker pipe34and a discharge pipe35, and an off gas outlet pipe31, an ozone destruct unit32and an off gas discharge pipe33.

The vent pipes29&30are provided to vent a residual air (ozone) contained in the treated water outlet discharge pipe28before the treated water is discharged through the discharge pipe35.

The discharge pipe35is connected to the siphon breaker pipe34such to maintain a designated water level36in the vessel19.

The off gas (ozonated air) flows from the vessel19into the ozone destruct unit32and then to the discharge pipe35. The ozone destruct unit32removes the residual ozone from the off gas.

The coagulation and flocculation system37comprises a coagulation recirculation pump38, a coagulant initial mixing chamber39, a static mixer40, an inlet pipe41and an outlet pipe42, and a coagulant supply43.

The coagulation recirculation pump38flow rate is preferably within 10 to 20% to the raw water inlet flow rate.

The coagulant mixing chamber39provides an initial, low gradient mixing, and the static mixer40provides a final high gradient mixing of the ozonated raw water and a coagulant.

The inlet and outlet pipes41&42are preferably perforated or slotted to provide a uniform raw water distribution in the vessel19and a “plug” like flow through the vessel19as indicated by an arrow25.

A second embodiment of the invention is shown onFIG. 2.

For the various embodiments disclosed here, the same reference numeral numbers are used for the same or substantially similar features. Hence, the raw water inlet piping1, the oxidation and coagulation and flocculation vessel19, and the treated water outlet and off gas discharge piping26are in essence the same as those shown inFIG. 1.

The oxidation system7and the coagulation and flocculation system37according to this embodiment are combined and they comprise the same but not all components included in the first embodiment.

The combined oxidation system7and the coagulation and flocculation system37comprise the recirculation pump8, the initial chemical mixing chamber9, the air (ozone) aspirator-mixer10, the inlet raw water pipe11, outlet raw water pipes44&45, the ozone generator15, the ozone in water monitor and ozone in water sensor16&17respectively, the hydrogen peroxide or other chemical supply18, the coagulant chemical supply43, the coagulant initial mixer chamber39, the static mixer40, the discharge pipe42.

The raw water flows into the recirculation pump8and it is split into approximately equal streams at the pump discharge; an oxidation stream44, and a coagulation stream45.

The recirculation pump8, in this case, functions as ozonation and coagulation recirculation pump.

The water flow rate into the recirculation pump8is approximately twice the raw water flow rate and it consists of the raw water flow from the raw water piping1and ozonated water flow from the ozonation vessel19, preferably, in approximately the same proportion.

The oxidation stream44flows through the initial chemical mixing chamber9into the air (ozone) aspirator-mixer10and the outlet pipe12and the discharge pipe13. The other chemical supply18is provided downstream of the initial chemical mixing chamber9.

The coagulation stream45flows into the initial mixing chamber39, the static mixer40and the discharge pipe46and the outlet pipe42. The coagulant supply43is provided downstream of the initial mixing chamber39, and it undergoes an initial low gradient mixing in the mixing chamber39, and a high gradient mixing in the static mixer40.