Investigation On Processing Of High Concentrated PEG Wastewater By Fenton-SBR Technology

Polyethylene glycol?PEG?is a kind of mild and low toxic organic polymer.Because of its good solubility,compatibility,hygroscopicity and stability,it is widely used in all kinds of industries.However,it is a difficult and biodegradable material,which will bring serious environmental pollution problems in the water body.At present,there are few reports on the treatment of high concentration PEG organic wastewater.With the in-depth study of the treatment of polyethylene glycol wastewater,how to efficiently and stable treatment of large amount of polyethylene glycol wastewater has become a hot spot.The polyethylene glycol wastewater in this project is a high concentration wastewater produced by the production of bromine hydrochloride in a pharmaceutical company.The molecular weight of polyethylene glycol is 400,that is PEG400.In view of its low pH,large chromaticity,high concentration of COD,and difficult biochemical degradation,the Fenton-SBR combination process is used to treat the wastewater.The best conditions for the pretreatment of Fenton,the starting process,operation and influence factors of SBR unit are deeply analyzed and studied.The optimum operating parameters of the process are determined and applied to the treatment of the actual wastewater,and the combination of the process is studied.The removal efficiency and impact load capacity of the process on the actual wastewater pollutants are also discussed.This research has important practical significance and provides a reference for better treatment of polyethylene glycol wastewater.?1?Orthogonal experiment was applied to study the best process conditions for pretreatment of simulated PEG400 wastewater by Fenton oxidation process.The experimental results show that the most important factor affecting the removal of COD in wastewater is the dosage of Fenton reagent,followed by the H₂O₂/Fe²⁺ ratio of Fenton reagent and the reaction time.The best process conditions for the pretreatment of PEG400 wastewater by Fenton oxidation process are as follows:the ratio of Fenton's reagent to the dosage of H₂O₂/Fe²⁺ is about 2.19,the dosage of FeSO4.7H₂O is 35g/L and the reaction time is 180min,and the removal rate of COD is 85.81%.?2?The biodegradability of Fenton wastewater after PEG400 oxidation was studied by comparing the oxygen consumption of breathing.The results show that the microbial respiration curve in the solution treated by Fenton is above the Fenton solution respiration line,indicating that the biodegradability of PEG400 wastewater after Fenton treatment can be greatly improved,and it can enter the subsequent biological treatment stage,indicating that it is technically feasible to use the Fenton reagent to preoxidize it.?3?Next,the process start-up of SBR degradation of PEG400 wastewater COD was studied.The results show that when the SBR reactor is completed by 22d,the growth of the sludge is obvious,and the properties of the sludge are good between SVI and 50?120ml/g.When the influent COD,ammonia nitrogen and total phosphorus concentration are 1200mg/L,60mg/L,and 12 mg/L,the effluent concentration can reach 162mg/L,7.2mg/L and 0.74mg/L respectively.The corresponding average removal rates are 86.5%,88%and 93.8%respectively.The system runs as a whole.In good condition,the effluent quality is stable,indicating that the microorganism in the sludge has high activity,and the activated sludge is successfully domesticated.?4?After SBR was launched,its operation parameters were optimized.The results show that the sludge concentration MLSS in the reactor is about 2.5g/L and SV30 is about 2.5g/L and SV30 is 28%.The optimum process conditions are DO control at 6mg/L,aeration reaction time 6h,precipitation time 1H,periodic operation time of 8h,HRT 20h,and water exchange rate of 40%after the optimization of the reactor concentration MLSS is about 28%.SBR can run 15d steadily under optimized process parameters,and the average removal rates of COD,ammonia nitrogen and total phosphorus are 92%,94.3%and 95%,respectively.Under this condition,SBR runs stably,and the effluent quality is good.?5?Fenton-aerobic combination process was applied to treat actual wastewater.The results of continuous operation for 30 days showed that the system was stable and the removal efficiency was good.The COD,ammonia and total phosphorus concentration of the effluent were stable at 92mg/L,4.3mg/L and 0.5mg/L,which basically met the requirements of the effluent.The overall COD removal rate is up to 98%,indicating that the Fenton-aerobic combined process has a better treatment effect on the organic matter in the actual PEG400 wastewater,and the technical route is completely feasible.?6?Finally,the impact load test of SBR system is carried out.The results show that the SBR system has a certain ability of anti load,and the COD removal effect is still good at the end of the cycle when the load impact is within the range.When the influent impact concentration has exceeded its bearing capacity,the COD value of the effluent from the SBR process system will be obviously improved,and the concentration of COD in the effluent will be restored to normal after the recovery of the original influent concentration,indicating that the system has not collapsed due to the load impact,but is only unable to deal with the organic pollutants that exceed its handling capacity during the impact cycle.After the high concentration of organic matter impact load,the sludge volume index?SVI?of the system showed a downward trend,indicating that the impact load of organic matter to a certain extent was beneficial to the improvement of the settling performance of SBR activated sludge.