Research On Wastewater Treatment Technology Of Glyphosate Production

Glyphosate is currently one of the most widely used pesticide herbicides in the world,but for every ton of glyphosate produced,about 4.5 tons of wastewater will be generated,and the environmental treatment cost is about 800-1500 yuan/ton.The wastewater contains some renewable resources,such as glyphosate（1.2-1.8%,w%）and glyphosate（3.0-5.0%,w%）.If these high value-added resources in wastewater can be recycled,it can not only reduce the existing environmental treatment cost to a certain extent,but also bring secondary economic value.Therefore,from the perspective of environment and economy,it is of great significance to treat glyphosate production wastewater in a green and economic way,recover high-value products in it,and reduce the risk of environmental pollution.In this paper,glyphosate production wastewater as the research object,using complex oxidation strategy to selectively prepare glycine from glyphosate production wastewater,using modified resin adsorption technology to recover glyphosate from glyphosate production wastewater,using sodium hypochlorite oxidation process to denitrification and reuse of glyphosate production wastewater,to achieve resource recovery and utilization of this wastewater.It provides a new way to recycle the waste water from glyphosate production.The research content and conclusions are as follows:（1）Composition analysis of glyphosate wastewater and screening of conversion reagents.The total nitrogen（TN）,total phosphorus（TP）and chemical oxygen demand（COD）of the membrane treated evaporation concentrate（No.2 wastewater）were about 2.96×10⁶ mg/L,35323 mg/L,163621 mg/L,6.88%and 0.12%,respectively.The TN of evaporative condensate（No.4 wastewater）is about 1100 mg/L.It was screened that the Fe²⁺/H₂O₂ system had the best effect on the preparation of glycine from No.2 wastewater.Fe³⁺-D301 resin has the best adsorption effect on glyphosate in No.2 wastewater.The Na Cl O oxidation system had the best effect on removing total nitrogen from No.4 wastewater.（2）The selective conversion of glycine from No.2 wastewater was achieved by complexation followed by oxidation.The effects of reagent ratio,dilution ratio,temperature and p H on glycine conversion were studied.The results showed that the best reaction temperature was 45℃,the best reagent ratio was 1:6,the best dilution ratio was 200～500 times,and the best reaction p H was 7～8.Uv-vis absorption spectrum and Fourier transform infrared spectrum showed that ferrous ion complexed with the hydrogen oxygen bond of glyphosate carboxylic acid group first,and then selectively broke the bond under the condition of hydrogen peroxide to obtain glycine.（3）Glyphosate was recovered from No.2 wastewater by Fe³⁺-D301 resin.The resin was characterized by scanning electron microscopy（SEM）,SEM equipped energy spectrometry（EDS）and X-ray photoelectron spectroscopy（XPS）.The results showed that the N atom on D301 resin formed Fe-N coordination bond with Fe atom.Thus,Fe³⁺is loaded on D301 resin.The adsorption isotherms and kinetic curves of Fe³⁺-D301 resin for glyphosate were consistent with Langmuir model and pseudo-second-order model,respectively,and the theoretical maximum adsorption capacity qmax=684.6 mg/g.XPS analysis showed that Fe on Fe³⁺-D301resin coordinated with the O atom on the P-O bond in glyphosate molecule to form Fe-O-P and adsorb glyphosate.The actual wastewater adsorption experiment showed that the maximum adsorption rate of glyphosate in 500.00 m L of No.2 wastewater was 74.65%when the dosage of Fe³⁺-D301 was 6.00 g.At the same time,Na OH,H₂SO₄ and Fe₂（SO₄）₃ could all be used as desorption agents,and the desorption rate of glyphosate reached more than 95.83%.（4）The effect of reaction temperature,p H,reaction interval and dosing method on the removal of TN in No.4 wastewater was investigated by sodium hypochlorite oxidation method.The results showed that at 80℃,reaction interval was 20 min（six times added）,dosing ratio was 1:3(the first three times:The highest TN removal rate was 99.45%（TN<40 mg/L）,and a good correlation was found between the amount of sodium hypochlorite（x）and total nitrogen removal（y）（y=0.02033x+166.99646;R²=0.85995）.The acute toxicity test of Microcystina aeruginosa showed that the evaporative condensates treated by steam mechanical re-evaporation（MVR）had good biodegradability.Finally,the amplification experiment was carried out,and the process device for removing nitrogen from glyphosate wastewater was designed.