Study On Phosphorus Removal Of Glyphosate Wastewater

Glyphosate is a kind of broad spectrum herbicide,which has low toxicity and high efficiency.lt gets rapid growth in recent years and now becomes one of the pesticides which have the largest output and consumption in the world. The production wastewater of glyphosate which has high salinity, high content of persistent compounds and large discharge is toxic and difficult to dispose. Before2009, glyphosate mother liquor wastewater was commonly reused as10%glyphosate agent by evaporation and enrichment treatment. However, the10%glyphosate agent which was made from mother liquid had high salt and poisonous and harmful substances content and was easy to harden the soil and destroy the ecological environment. So China issued NO.1158and NO.1744announcement in succession to stipulate that10%glyphosate agent can not be produced after the end of2009and from September2012glyphosate mixed water product,the content of which is less than30%is no longer retain the original pesticide registration certificate. So how to effectively dispose and recycle the large amount of wastewater at low cost becomes worth studying.This thesis mainly studied the treatment of glyphosate wastewater by precipitation, oxidation and the combined method, and an efficient glyphosate production wastewater treatment technology was found. Due to the high phosphorus content of the glyphosate waste water, the thesis took the iron salts as precipitant for its strong complexation with glyphosate and the phosphoric acid root. In addition to the precipitation, complexation and the flocculation effect when the TP was removed, iron ion in Fenton oxidation system also acts as the catalyst, can greatly improve the oxidation efficiency.This paper first examined the dephosphorization effect of iron and calcium salts and found that iron salt was much better than calcium salt. Then we further studied the influence of GLP simulated sample pH, complexing agent dosage, glyphosate concentration, ionic strength to the effect of ferric salt complexing glyphosate.To treat the glyphosate simulated sample (TP=400mg/L) under the condition of pH=2.4, when iron phosphorus mole ratio was1.5:1, the TP removal rate reached97%, but after processing TP concentration was still more than10mg/L. Secondly the paper researched the degradation of glyphosate in Fenton, NaC1O and ferrate oxidation system. Results showed that these three kinds of system had certain degradation effect to glyphosate simulated sample (TP=400mg/L) and the degradation rate reached60-70%at best. The complexing of ferric iron to glyphosate may hinder oxidant attack glyphosate molecules, resulting in a decline of glyphosate degradation rate,so NaC1O oxidation system showed a higher degradation rate to glyphosate simulated sample. Chlorine ion can significantly influence the glyphosate oxidation effect of Fenton reagent, when the mass fraction of NaC1was5%, glyphosate degradation rate dropt to below10%,which was only about20%of the none-chlorine system, however the removal rate of TP was not affected. In Fenton oxidation system, under the condition of the initial pH=3,when the iron phosphorus mole ratio was1.5:1, adding1ml H2O2in100ml simulated sample and adjusting the pH to7after two hours reaction under50℃,the TP removal rate could reach99%and total phosphorus concentration can be reduced to0.5mg/L, which can meet the emission standard of our nation. Adding1ml NaCIO solution in100ml glyphosate simulated sample(TP400mg/L), when iron phosphorus mole ratio=1.5:1, after2hours reaction, TP can be reduced to about3mg/L.This paper finally studied the dephosphorization of glyphosate industry wastewater to verify the feasibility of the method,it was found that the treatment effect of wastewater and the simulated sample had good consistency. After the treatment of glyphosate production wastewater the TP of which were366and1000mg/L by combined precipitation and oxidation processes, TP concentration can drop to below2mg/L.This combined method is expected to recover phosphorus resources and has a good industrial application prospect.