Glyphosate pesticide wastewater pretreatment solution

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Sales of glyphosate wastewater pretreatment solutions have been good. However, according to years of investigation and monitoring by the plant protection and environmental protection departments, it was found that 10% glyphosate water can cause soil compaction and cause serious soil and water pollution. To this end, the Ministry of Agriculture, Industry and Information Technology jointly issued the No. 1158 document at the beginning of this year, stipulating the ban on the production and sale of 10% glyphosate water from next year. Therefore, the problem of how to handle the mother liquor is almost every glycine method. The birth and death card of the phosphine production plant.

1.2. Methods for treating glyphosate mother liquor In principle, there are three methods for the treatment of mother liquor: one is to reform the process to achieve clean production and achieve zero discharge; the other is to recycle glyphosate and glyphosate first, and then The residual liquid is harmlessly treated; the third is to combine the chemical physics and biochemical treatment to treat the diluted mother liquor harmlessly. The problem of technological reform can not be solved overnight, and it is necessary to carry out long-term experimental exploration. The more realistic is to use the second and third methods to solve the problem of glyphosate mother liquor treatment.

1.3. Problems with Membrane Separation Technology In the first place, membrane separation technology was used to recover glyphosate in mother liquor. However, experiments have shown that (nanofiltration) membrane separation technology can demineralize and concentrate thin mother liquor, but there are also a series of Technical, economic and environmental issues: (1) Not adaptable According to our survey, not all glyphosate mother liquors can be concentrated and separated by nanofiltration membranes, and some plant mother liquors are under pressure of 3.0 MPa. There is no drop of water; (2) How to dispose of the concentrate The concentrated mother liquor contains a large amount of high concentration of glyphosate, organic by-products and phosphite in addition to glyphosate. It is very difficult to prepare more than 30% of glyphosate in the concentrate. Even if it is formulated, the cost is relatively high. (3) How to dispose of the membrane effluent In order to elute the high concentration of salt in the mother liquor, it is necessary to adopt a 3-4 grade nanofiltration elution process. Each treatment of 1 ton of mother liquor should produce more than 1.2 tons of membrane effluent, and the effluent COD 5000-8000 mg/ L, salinity 4% -5%, total phosphorus 1000-2000 mg / liter, how to deal with this part of the water is still a problem. (4) Membrane fouling and high operating costs It is self-evident that in the process of concentration and separation of glyphosate mother liquor, membrane fouling is very serious. Therefore, frequent membrane cleaning and membrane column replacement will result in high operating costs.

1.4 Difficulty of physical-biochemical combined treatment From the perspective of sewage treatment, the physicochemical-biochemical treatment of glyphosate mother liquor is also very difficult, mainly because: (1) COD concentration is between 40000-50000 mg/L. Poor oxidizability and biodegradability, the ratio of BOD/COD is less than 0.2; (2) the total salinity is as high as 15%-20%, so how to reduce the concentration of salt to the concentration range that can be tolerated by biochemical treatment with low cost method Inside, it is the biggest problem in the treatment of glyphosate mother liquor. (3) Total phosphorus is as high as 20,000 mg/L, especially one-third of which is phosphite which is difficult to oxidize and difficult to precipitate.

In summary, for high-concentration, multi-component glyphosate mother liquor, it is obviously not possible to use a single technology for treatment. It is necessary to use a combination of various physical and chemical technologies to make it possible to treat the grass in a reasonable treatment cost. The phosphine mother liquor is treated to a degree of detoxification.

2.2 Pretreatment Process 2.3 Process Description Glyphosate wastewater is acid-adjusted to pH=3.0-3.5, then NaClO is added for chemical oxidation reaction. The reaction is stirred for 1 hour, and the effluent enters the multi-dimensional electrocatalytic reactor for secondary oxidation. Reduction reaction. The organic phosphorus, phosphorous and other components in the wastewater can be oxidized and decomposed into orthophosphate to be removed. The refractory organic matter is simultaneously decomposed into small molecules of easily degradable organic matter. The mechanism of electrocatalytic oxidation is to directly degrade organic matter by anodic reaction, or to generate organic radicals such as hydroxyl radicals (?OH) and ozone by anodic reaction. This degradation pathway makes the organic matter decompose more thoroughly and is not easy to produce poisonous intermediates. More in line with environmental protection requirements.

2.4 Operating cost 2.4.1 electricity fee is about 30 yuan / ton of water 2.4.2 pharmacy fee, need hydrogen peroxide for sewage 5 ‰, hydrogen peroxide price is 2,000 yuan / ton, then pharmacy fee = 10 yuan / ton of water; waste acid and Other medicines are 40 yuan / ton. Total operating cost = 80 yuan / ton of water.
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