Organophosphorus Compound Pollution And Prevention

With the development of modern industry, the production and synthesis of organic compounds are increasing day by day. Wastewater discharged from chemical, paper, rubber, dye and textile printing and dyeing, pesticides, coking, petrochemical, fermentation, pharmaceutical and medical and food industries often contains organophosphorus compounds, causing environmental pollution, deterioration of surface water bodies, and threatening human health. The pollution of organophosphorus compounds has received increasing attention.

There are many methods for the treatment of wastewater containing organophosphorus compounds. To sum up, the methods commonly used at home and abroad can be divided into oxidation method, biochemical method, adsorption method and hydrolysis method:

1. Oxidation method

(1) Ozone oxidation method

The ozone oxidation method is suitable for the treatment of pesticide wastewater with low concentration, difficult to be biodegraded or toxic to organisms, such as malathion, phosphine, etc. Generally, it generates schizophrenia compounds, and finally generates CO2 and H2O, without secondary pollution. While decomposing organic matter, it also has decolorization, deodorization and bactericidal effects. The disadvantage of ozone oxidation is that the ozone generator consumes a lot of electricity, so it is only suitable under the condition of sufficient electricity supply.

(2) Wet oxidation method

It is a method of heating and pressurizing wastewater in the presence of air to greatly reduce COD, BOD and suspended solids. The method is suitable for treating substances with high concentration, high toxicity and refractory biodegradation, and the method has low COD removal efficiency. Using wet oxidation method to treat wastewater, the removal rate of organic phosphorus is about 80 percent . The reaction is mainly based on hydrolysis, and organic phosphorus is converted into hydrolyzed products H3PO4, HCl, CH3OH, etc., and finally phosphorus is recovered in the form of Ca3(PO4)2.

(3) Chlorine oxidation method

Chlorine-containing oxidants include Cl2, ClO2, hypochlorite, etc. Oxidation works best with sulfuric acid at pH < 3.="" treat="" malathion="" wastewater="" by="" chlorine="" oxidation="" method,="" neutralize="" it="" with="" caustic="" soda="" to="" ph="" 7,="" pass="" c2="" to="" ph="" 2-3,="" separate="" out="" the="" bottom="" oily="" substance,="" add="" caustic="" soda="" (accounting="" for="" 2%="" of="" the="" wastewater),="" and="" stir="" at="" 40°c="" for="" 4pu6h="" ,="" the="" toxic="" phosphorus="" content="" was="" reduced="" to="">

2. Biochemical treatment

(1) Activated sludge method

Biochemical treatment is to mix the homogenized wastewater with activated sludge containing domesticated organophosphorus-resistant bacteria, and conduct aeration. After aeration, it enters the sedimentation tank, and is treated by the sedimentation tank for secondary aeration. Aeration biochemical treatment can reduce BOD to 13mg/L, and phosphorus in organic phosphorus can be recycled as biological nutrients. Biochemical treatment method is widely used and the effect is better.

(2) Algae treatment method

Organophosphorus pesticides can be effectively removed by green algae, but when treated with algae, sometimes extremely toxic and stable intermediates are formed, and when algae treat parathion, more toxic intermediates are obtained. Treatment of some organic phosphorus wastewater with Chlorell Valgaris at 20 degree for 2 to 30 days, the removal rate can be 90 percent to 98 percent .

(3) Enzymatic method

Horseradish peroxidase can be used for enzymatic treatment of wastewater containing phenol, cresol, xylenol and trisulfuric acid, which can achieve better results.

3. Adsorption method

Organophosphorus adsorption is better, and activated carbon can also be used after alkaline hydrolysis. Activated carbon can be regenerated by steam, such as parathion, EPN, etc. Tributyl phosphate in wastewater can be removed by fly ash and clay as adsorbents, but adding nitric acid in an acidic medium can improve the removal rate. Polyvinyl alcohol or ketone can be used to adsorb trace amounts of organophosphorus compounds in water.

4. Hydrolysis method

(1) Acid hydrolysis method

Acid hydrolysis can break the basic group of organophosphorus molecules to generate orthophosphoric acid. The disadvantage of the hydrolysis method is that the equipment is required to be resistant to corrosion. In the high temperature and high pressure treatment of phosphoric acid wastewater, pH34, pressure 4050atm, 200250 degree , the inorganicization rate of organic phosphorus can reach 90 percent 100 percent .

(2) Alkaline hydrolysis method

Alkaline hydrolysis commonly used alkaline hydrolysis or lime milk. Under alkaline conditions, the acid anhydride in the organophosphorus molecule is easy to break, so the alkaline hydrolysis has a good removal effect, but the organic phosphorus is generated, the final recovery is difficult, and the residue is difficult to handle.