Study On The Efficiency Of ASBR-SBBR Process For The Nightsoil Wastewater Treatment

In order to developing high-efficient,low-consumptive treatment techniques for sewage, in this paper, based on the character of nightsoil wastewater—containing both highly concentrated nitrogen and organic matters, appling new type,high-efficient "ASBR-SBBR"process to treat it and study on the efficiency of the combination system, finding the suitable operating parameters. To lowly-efficiency of ASBR under low temperature,the measure to improve the sluge concentration of ASBR is adopted,and improving the treating-efficiency under low temperature.Based on high ammonia content(500⁶00mg/L),biodegradability(BOD₅/COD=0.2) in effluent from ASBR, the effection of organic load,ammonia content and water temperature to nitrogen removal in SBBR is discussed and resolving the problem about shortage of carbon source by and find high-efficient SND in SBBR,strengthen the ability of nitrogen removal by the approach to improving the carriers package.Besides,comparisons about the bio-refractory organic compounds and chroma of effluent from SBBR were made between ozonization process and activated carbon adsorption process. 1) The experiment about effection of organic load and water temperature to efficiency of ASBR showed:when water temparature was 35℃,loading rate was 10kgCOD/m³Â·d and hydraulic retention time(HRT) was 24h, COD was 16000mg/L in influent,and COD was 2600mg/L in effluent, removal rate of COD was 86.4%. In winter, the experiment showed: when water temparature was 15℃, removal rate of COD decreased to 54%,in this time, improved the MLSS from 25g/L to 40g/L, removal rate of COD can increase to 63%, when prolonged HRT to 48h, removal rate of COD was 77%. 2) Comparision was made between SBBR and SBR, the experiment showed: removal rate of COD was 86.3%,removal rate of NH₄⁺-N was 99.2%,removal rate of TN was 84.5% when SBBR(the carriers package was 30%) was used to treat effluent from ASBR; in SBR, removal rate of COD was 87.9%,removal rate of NH₄⁺-N was 97.6%,removal rate of TN was 75.7%,efficiency of nitrogen removal in SBBR superior to SBR. 3) The experiment of treating anaerobic effluent by using SBBR reactor showed that: on the conditions of organic loading was 0.4kgCOD/m³.d, hydraulic retention time was 12 hours, the carriers package was 30% and water temperature was 25℃, which can make the COD(2600mg/L), NH4+-N(500mg/L) and T-N(500mg/L) in the influent declined to COD(350mg/L), NH4+-N(7mg/L) and T-N(80mg/L) in the effluent, 86.3% of the COD, 99.2% of the NH4+-N and 84.5% of the T-N can be removed, and the high efficiency of nitrogen removal by SND was achieved in the SBBR. 4) The experiment about the influence of NH4+-N to efficiency of SBBR on the treatment of anaerobic effluent was investigated, the experimental results showed: when the concentration of NH4+-N more than 200mg/L, the NH4+-N removal rate declined from 98.4% to 48.3%, nitrification rate decreased from 8.2mg/L.h to 4.5mg/L.h; activities of nitrification bacterium was obviously inhibited by NH4+-N, when the organic loading less than 0.6kgCOD/m3.d and discharge rate less than 1/4 in the SBBR, which can reduce NH4+-N concentration less than 200mg/L and avoid inhibition of NH4+-N to the nitrification. 5) The problem on shortage of carbon source in the anaerobic effluent, the experimental result showed: under 25℃, 8% of raw waste water was directly put into SBBR, the ratio of BOD5/TN can be improved to 3.2, the performance of nitrogen removal can be effectively improved, and can make TN of the effluent less than 20mg/L, meeting the national standards. 6) In winter, the experiment on the influence of low temperature to efficiency of SBBR to treating anaerobic effluent was investigated, the experimental results showed: when the water temperature declined from 25 ℃to 13 ℃, the activity of microorganisms in the reactor decreased respectively, the content of dehydrogenase declined from 8.21ugTF/mgMLSS.h to 3.29ugTF/mgMLSS.h, in the effluent, the TN increased from 56.3mg/L to 81.2mg/L ,the TN removal rate reduced from 89.2% to 80%. 8% of raw wastewater was directly put into SBBR reactor and increased the carriers package from 30% to 45%, which can improve the TN removal rate to 92.8%. 7) The undegradable COD that remain in the biochemical treatment effluent can be well adsorbed by activated carbon, the adsorption capacity is 150mg/g, this adsorption process accord with the equation of Langmuir Freundlich.