Study On The Treatment Of Nonylphenol Ethoxylates Wastewater

Nonylphenol ethoxylates（NPEOs）are a group of nonionic surfactants that are most often used in detergents,emulsifiers,and dispersing agents in household,agricultural,and industrial applications.As a consequence of the use,discharge of NPEOs occurs in the environment via industrial effluents and domestic sewage and it can be biodegraded to generate nonylphenol（NP）and short chain NPEOs which are more toxic,more lipophilic and more persistent than the parent substance.In this study we have evaluated reactions of Fenton’s reagent with high concentration NPEOs wastewater.And a new reuse method for Fenton sludge by ferrous sulfide（FeS）was investigated.The biodegradation behaviors of NPEOs under aerobic and anaerobic were investigated.And the degradation behavior of NPEOs in aerobic trickling filter had been investigated.The result were shown as follows:（1）The Fenton oxidation process was applied in the treatment of an actual high concentration NPEOs wastewater.The orthogonal experiment indicated that the order of degree of influence on the COD removal was molar ratio of H₂O₂/Fe²⁺,reaction time,dosage of H₂O₂,and initial pH.The single-factor tests were carried out to determine the optimal conditions,and the results were H₂O₂ dosage of 76.32mmol/L,molar ratio of H₂O₂/Fe²⁺of 3,pH value of 5 and reaction time of 2h.Under the optimum operation conditions,the COD removal efficiency were 85.6%.（2）A large number of ferric sludge（SS=8.724g/L）would be produced after the Fenton oxidation of the wastewater and must be disposed appropriately.A novel process for Fenton sludge reused by low-cost ferrous sulfide（FeS）was also investigated.Experimental results show that the Fenton sludge could be reduced to produce a certain amount of Fe²⁺in the acidic mixed liquor by ferrous sulfide.This mixed liquor from Fenton sludge could be used as the new catalyst in the Fenton process and was also highly effective for the NPEOs wastewater treatment.（3）Under aerobic,anaerobic or A/O conditions,the NPEOs wastewater had a degradation effect in the reators.When the test cycles were 30 days,and COD of the NPEOs wastewater influents was 5000mg/L,the COD removal was 57%in the anaerobic reator,the COD removal was 70%in aerobic reator,and the COD removal was 80%in the A/O process.（4）The results showed the NPEOs wastewater was easily degraded in the aerobic trickling filter process.When the COD of influent was 1000-2000mg/L,the COD of effluent was 100-500mg/L.（5）The effect of environment factors on microbial diversity were investigated by high throughput sequencing.The results showed that,Acidobacteria was the most predominant phylums of bacteria and the ratio in total bacteria,and the ratio in total bacteria was over50%.Sphingobium,Halothiobacillus,Chryseobacterium,Pseudoxanthomonas,Salinispora,Azovibrio,Novosphingobium were discovered as the dominant genuses in seven samples,respectively.