Study On The Treatment Of Swine Wastewater With Two-stage Anaerobic Sequencing Batch Reactor (ASBR)

Swine wastewater is one of the main agricultural pollutant resources,which has created a large number of pollutants,such as organic matters and nitrogenous matters.These pollutants not only aggravate the shortage of water resources,but also seriously restrict the implementation of sustainable development strategy.Therefore,the efficient removal of organic matters and nitrogen substances has become an important direction in the field of controlling water pollution and improving water environment.The current biochemical processes occurred under the condition of no molecular oxygen existence.The anaerobic wastewater treatment by ASBR was one of the most economical techniques.In this study,the methanogenic and anammox reaction processes in two-stage anaerobic sequencing batch reactors were started up successfully.The experimental object was man-made swine wastewater,it analyzed the main factors which affected the methanogenic process and anammox process,including the influent substrate concentrations,temperatures,pH,metal ions and so on.The startingIV conditions and running processes of the two-stage ASBRs were studied.Itproved that the existence of Methanogenic bacteria and Anammox bacteria by scanning electron microscope(SEM).The results are as follows:After 50 days,the methanogenic process was started up successfully in the first anaerobic sequencing batch reactor(ASBR NO.1)with the formation of anaerobic granule sludge,whose seed sludge were from sewage treatment plant in J city.When the influent organic concentration was 3000 mg/L,the effluent concentration of organic matters was in the range of 80 mg/L~100mg/L and the removal rate of COD was close to 95%.In order to ensure the stable operation of two-stage reactors,the operation parameters were continuously adjusted.In the whole process,p H was changed between 7 and7.5,temperature was stable at 35? and the effluent must be discharged out after a period of 6 to 8 hours.Anaerobic ammonia oxidation(Anammox)process was also started up in the second reactor(ASBR NO.2).The whole start-up process could be divided into four stages: the initial sludge adapted stage(50 days),the sludge showed active stage(50 days),the activity of sludge improved stage(175 days)and the activity of sludge stable stage(75 days).The red or yellow-red anammox granular sludge has been formated since 350 days.Finally,the ammonia nitrogen and nitrite nitrogen concentrations of the influent were 240 mg/L and320 mg/L,respectively.And the nitrate nitrogen of the effluent was 15mg/L~20 mg/L.Also,the effluent quality met the wastewater emissionstandards.The removal rates of ammonia nitrogen and nitrite nitrogen were92% and 94%,respectively.The removal ratios of ammonia nitrogen,nitrite nitrogen and nitrate nitrogen were close to 1:1.32:0.26.The sludge was observed by scanning electron microscope for analysis of their surface morphology,the granular sludge in ASBR NO.1 was made up of methanogenic bacteria,which were Methanosarcina thermophila and Methanothrix that co-existence by crossing each other.In ASBR NO.2,the results showed that the grain-sludge appeared irregular ellipsoid and was mainly made up of red anaerobic ammonia oxidation bacteria,whose diameter size was less than 1 ?m.Combine the methane production process with anaerobic ammonia oxidation process,and maintain the simulated wastewater into the two reactors.In the whole process,the HRT of the first reactor was 8 hours and the second reactor was 12 hours.Finally,when the COD concentration of the influent was1500 mg/L and the NH4+-N concentration was 120 mg/L,the removal rates of COD and NH4+-N were close to 95% and 100%.Thus,it achieved an efficient removal of organic matters and ammonia nitrogen in wastewater.