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Using the Split Feed Anaerobic Baffled Reactor as the Pretreatment Technique to Treat the Countryside Sewage

Author: HePengPeng
Tutor: RenYongXiang
School: Xi'an University of Architecture and Technology
Course: Municipal Engineering
Keywords: SFABR Constructed Wetland Low concentration Countryside sewage Pretreatment
CLC: X703
Type: Master's thesis
Year: 2011
Downloads: 73
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Abstract

To develop a wastewater treatment technique with high efficiency and stability, low investment, low energy consumption and easy operation, based on the in-depth investigation results of pollution sources, water quantity and quality characteristics and its influencing factors of new countryside along Fenghe River, and also to solve the problems of low efficiency, low stability and pore clogging in constructed wetlands (CWs), and so on, Split Feed Anaerobic Baffled Reactor (SFABR) was chosen as a new pretreatment technique of CWs for treating countryside sewage. In this paper, how SFABR designed, how SFABR started-up rapidly and whether the SFABR treatment efficiency highly and stably fed by the synthetic wastewater and actual restaurant sewage which pollutants concentration at the level of the local new countryside sewage were studied. Whether SFABR can be used as a pretreatment technique of CWs for treating low concentration countryside sewage also was preliminarily analyzed. The experiment influent of SFABR were synthetic wastewater initially and Xi’an University of Architecture Technology restaurant wastewater finally. The main results and conclusions were shown as follows:(1) The investigation results of Fenghe river showed that most of paper mills had been closed, wastewater from universities and middle schools had also begun to treat, the most important and urgent part was countryside sewage treatment at present; Countryside along the Fenghe River which economic level was low, distribution was decentralize, water quality and quantity variation coefficient were high, winter temperature was low, and so on. The new countryside wastewater was polluted more seriously and intensively to be treated more easily and urgently.(2) SFABR could started-up successfully and rapidly at low temperature and low concentration, which could more effectively reduce the organic loading rate (OLR) for the CWs and distribute organic matters of each compartment than Normal Feed ABR(NFABR) The influent COD was about 200 mg / L, the influent ratio of four compartment was 4:3:2:1, the treated wastewater temperature was 18~22℃, HRT was 24 h, COD: N: P was 100: (14 ~ 17.5): (1.5～3.5) during the SFABR start-up. The start-up time was only for 40 d. COD removal rate was 47.8 ~ 48.5 % by the SFABR stably. During the SFABR stabilized, the difference of COD removal efficiency among each compartment became more close and almost reached to the same at last.(3) SFABR had a low remove efficiency of COD due to the low influent COD concentration when HRT fixed. Because the effluent COD could not below 100 mg/L no matter what influent COD concentration, the total COD remove capacity was very limited and obviously lower than high strength influent; HRT had little effect on the SFABR for treating low concentration wastewater, so that HRT could be shorten appropriately within a certain range in order to reduce the reactor volume and construction investment.(4) The major factor was OLR between Hydraulic Loading rate and OLR caused by HRT reduced when HRT > 5 h. The relation of OLR and the COD removal rate were as follow: When the OLR greater than 2.5 kg / (m3?d), the COD removal efficiency decreaseed by OLR increasing; when the OLR less than 0.8 kg / (m3?d), the COD removal efficiency did not changed significantly by the OLR increasing. It also showed that a small range of OLR change could not affected on the COD removal rate, which reflected SFABR resistance to the impact on OLR.(5) SFABR could not obviously remove N and P. NH4 +-N removal rate was negative because of the ammunition;TP removal rate was also negative, because phosphorus released under anaerobic conditions. ORP values of each compartment were below the -200 mv further indicated that it was easy to release phosphorus. The actual gas production was much lower than the theoretical amount of methane at low OLR.(6) When SFABR fed by actual restaurant wastewater, the remove efficiencies of SS and animal and vegetable oils were both more than 90%, effectively reducing the risk of carrier clogging and plants death of subsequent CWs. The COD removal rate is also higher than SFABR fed by synthetic wastewater, from 45% to 56%.

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