Production of organic phosphorus pesticides will produce organic phosphorus wastewater, such as the production of dimethoate will produce high concentrations of organic phosphorus wastewater, the COD value of 10000 mg / l or more, containing organic phosphorus about 1000 mg / l. Wastewater contains dimethoate, methanol, dimethylamine and other substances, available extraction or distillation and other methods of recovery, and then use biological method for harmless treatment. In order to ensure the normal treatment of biological treatment, improve the treatment effect, must be appropriate pre-treatment, Dongguan wastewater treatment summary of the following methods are:
1, activated carbon adsorption method: the waste water can be activated with activated carbon to remove a part of the biological difficult to degrade and biological treatment of harmful substances.
2, wet oxidation method: COD of wastewater such as more than 50000 mg / l, this method can be used. Wastewater temperature at about 180 ℃ and 20 ~ 50 kgf / cm 2 under the pressure of oxidative decomposition of organic phosphorus, organic sulfur more than 80%, the remaining low molecular weight compounds, it is easy to be biodegradable.
3, static method: the waste water in the biological treatment stage before the first standing in the pool for more than three days, so that some of the harmful substances hydrolysis, and many inorganic matter down.
4, alkaline solution: the wastewater pH adjusted to 12 ~ 14, more than 80% of organic wastewater will be destroyed and become an intermediate product.
5, acidic hydrolysis: usually use low-pressure acid solution. Dongguan wastewater treatment plant introduced acid to make the acidity of wastewater to 0.5N, pressure 4 ~ 6 kgf / cm 2, temperature 120 ~ 150 ℃, acidification time 1 to 2 hours, organic phosphorus conversion to inorganic phosphorus efficiency of 70% the above. And then put the appropriate lime milk. After the pretreatment of waste water for biological treatment, the general use of aeration tank, the aeration time of about 15 to 20 hours per cubic meter of volume load per day of about 0.3 to 0.8 kg of BOD (biochemical oxygen demand), the removal rate of about 80 to 90%, while the COD removal rate of about 50 to 70%. A biological treatment of less than the provisions of the national wastewater discharge standards, often to the second biological treatment, or the use of activated carbon adsorption method for further processing.
The production of parathion wastewater contains p-nitrophenol, parathion, sulfide, salt and other substances, and also contains a considerable amount of hydrochloric acid and make the wastewater acidic, the pH value of about 1, BOD is about 4000 mg /Rise. In the biological treatment, the lime is neutralized in the neutralization tank to bring the pH to 6.8, then the homogeneous pool is allowed to mix the waste water and then enter the aeration tank using the activated sludge containing the acclimated specialty bacteria Treatment, BOD can be reduced to 10 ~ 20 mg / l, aeration tank by BOD0.5 ~ 0.6 kg / (m 3 · day) volume load design, BOD removal rate of 85 ~ 90%, phenol compounds can be removed 90 ~ 98%.
Chemical oxidation can also be used to deal with parathion wastewater. For example, after the precipitation of waste water into the decomposition tank, can be added with caustic soda to pH 8.5, and heated to 70 ~ 80 ℃ for decomposition; can also be added bleaching powder, after 7 to 10 days after decomposition of parathion content Down to 1 ppm.