Experiment On The Treatment Of Electro-osmotic Dewatering Wastewater By Hydrolysis-AO-MBR Process

In recent years,how to get the safe and reasonable sludge disposal,so as to reduce the two pollution,is a problem of concern.The dry sludge dewatering is a prerequisite for the disposal of sludge.The sludge removal of water as a by-product of sludge dewatering,contain large amounts of organic matter and ammonia nitrogen,and poor biodegradability.In general,the sludge removal of water can be directly with the sewage water treatment system will be mixed into the water,but for sludge disposal industry alone,there is no large-scale sewage treatment system,need to separate treatment compliance after discharge.This paper studies the quality characteristics of electro-osmotic dewatering wastewater.We find that it has high organic matter,high nitrogen and high alkalinity.According to the characteristics of this kind of wastewater,contact the domestic and foreign related research and engineering experience,the hydrolysis-AO process has been chosen.In follow experiment,hydrolysis-AO-MBR process has been used.The main research contents and conclusions are as follows:(1)The starting method and the operation during the startup of Hydrolysis-AO process have been discussed.The results showed that the effluent concentration of COD and ammonia nitrogen were under 150mg/L and 10mg/L.(2)Influence on the effect of HRT on sewage treatment was explored that the removal rates of COD and ammonia nitrogen were along with the increase of HRT in some range.When HRT stays more than 48 hours,COD removal rate is almost stopped growing,may be due to the wastewater containing refractory material.Ammonia nitrogen removal effect is good,the removal rate can reach 98.64%.(3)Influence on the effect of DO on sewage treatment has been researched.It is found that the appropriate increase the dissolved oxygen can improve the removal effect of COD and ammonia nitrogen.Low dissolved oxygen can limit the life activities of aerobic microorganisms and deteriorate pollutants degradation efficiency,while high dissolved oxygen can cause excessive oxidation sludge,aging faster.Considering the energy consumption factors,control the pool of dissolved oxygen in 2 ~ 3 mg/L.(4)Control dissolved oxygen below 0.2 mg/L in hydrolysis pool,below 0.5 mg/L in oxygen pool,p H of dissolved oxygen aerobic pool in 7 ~ 8,dissolved oxygen in 2 ~ 3 mg/L,HRT of anoxic pool and anaerobic-aerobic pool is 48 h.Reflux ratio of nitrifying liquid is 1:1,sludge reflux ratio is 1:1.Under the condition of the system stable running 60 days,the average removal rate of COD was 88.04%,the average removal rate of ammonia nitrogen is 94.49%,average effluent COD was 120.76 mg/L,ammonia nitrogen average of 9.27 mg/L.(5)Because of the great fluctuation of the dewatering water quality,the MBR system is added to guarantee the treatment effect.Due to the discharge standards of Standard for Pollution Control on the Landfill Site of Municipal Solid Waste(GB16889-2008)has been changed to Wastewater quality standards for discharge to municipal sewers(CJ343-2010),HRT of the anaerobic pool and the anaerobic-aerobic pool has benn changed into 30 hours.Determine the best working condition of the aerobic pond dissolved oxygen in 2 ~ 3 mg/L,the optimal HRT of anaerobic pool and anaerobic-aerobic pool of 30 h.The ratio of nitration liquid is 200%.The average removal rate of COD was 96.11%,the average removal rate of ammonia nitrogen was 98.69%.(6)The effect of hydrolysis acidification pretreatment on the system has been discussed,it is found that the removal rates of COD was not obviously reduced,the concentration of ammonia nitrogen in effluent is higher than that of influent.B/C values increase from 0.26 to 0.38,it is clear that the purpose of hydrolysis acidification pretreatment has been achieved.(7)The operation parameters of the membrane module have been researched,keep the run/stop time in 8 min / 2 min,work pressure matains 10 kpa,gas water ratio stays in 15:1,permeate flux of membrane is 14 L/ m2 h.It is found that the biofilm formation of ultrafiltration membrane surface has a significant effect on the retention of COD,the rejection rate was 45.5%,while has no obvious intercept effect of ammonia nitrogen.The existence of membrane module ensures low turbidity of effluent and stable water quality.(8)The equipment of dealing with electro-osmotic dewatering wastewater has been developed.For 50 specifications of the equipment,the daily water treatment capacity of equipment is 12.8 tons / day,and the cost investment is 192 thousand yuan.