Study on the treatment of domestic wastewater by anaerobi baffled reactor厌氧折流板处理生活污水研究.doc

Study on the treatment of domestic wastewater by anaerobic baffled reactorAbstract: The experiment for the treatment of synthesized domestic wastewater by anaerobic baffled reactor (ABR) was conducted at room temperature. The findings indicated that the ARB reached the best removal rate at temperature of 25 and hydraulic retention time (HRT) of 24 h. HRT, water temperature, organic loading rate and influent concentration are the major factors influencing the removal rate and decreasing the HRT and increasing the organic loading rate caused the decreased chemical oxygen demand (COD).Keyword: ABR; anaerobic treatment; domestic wastewater; influence factorIntroductionHigh-rate anaerobic technology, having the merits of energy-saving, low production of activated sludge, is a type of sustainable development wastewater treatment technology and has been widely used in the treatment of high concentrations of organic wastewater. ARB, for instance, has attracted a lot of attention for its simple structure, high removal rate, quick set up and stabile operation. The biggest character of ARB lies in its up and down baffle, with which the influence can travel in both rooms, making the bacteria live in different location and the gas release easily.ABR set-up experimentSet-up styleFor ARB, the start-up styles are as follows: high loading rate and low loading rate set-up. The high loading rate is taken in the present experiment.ABR set-up processThe set-up time chose at mid-April with the room temperature of about 18 and the temperature keeps increase and it was probe to set up. The set-up started at fourth April and ends at fifth July, about a month it takes.Acclimation of sludgeAcclimation of sludge stage, operated at low loading rate, is a process cultivated the needed sludge. Based on the previous studies, the acclimation of anaerobic sludge takes more time.The acclimation stage starts at April and the temperature is about 15-23 and keeps increasing, good for the growth of sludge. The COD concentration in influence stays around at 900 mg/l and Ph of some 7. Black sludge is found in ARB after a-week operation and the operation keeps for twenty days until the removal rate stays relatively constant. Results and discussionFig.4.1.3 COD removal rate with timeIt can be seen in Fig.4.1.3 that when HRT is between 8h and 36h, COD removal rate, to some extent, is proportional to HRT and stays stable; that is to say, the longer HRT stays, COD removal rate gets. As HRT increases from 8 to 24h, the removal rate increases from 20% to 38%, increasing merely 20%. When HRT increases from 24h to 36h, the removal rate increases almost 50% but when HRT increases from 36h to 48h, the removal rate changes a little. It is apparent that increasing HRT significantly causes COD removal rate increase when HRT is at 24-36h. taking all the factors, 36h is the needed time water stays in ABR.Conclusion1. The sludge needed in ARB must be activated fully or the set-up will take a long time or fail.2. The water used in ARB should be the domestic wastewater with the addition of trace elements. Low loading rate and long HRT are the key to the set-up of ARB.3. When the concentration of COD is constant, the longer the HRT, the higher the removal rate of COD. When the HRT stays constant, the higher the concentration of influence, the higher the removal rate of COD; the removal rate increases insignificantly after the COD concentration reaches a high level.4. The high level of volatile fatty acids (VFA) indicates that the bacteria are in the domain position and controlling VFA is vital to the growth of the bacteria.AcknowledgementsWe gratefully acknowledge Dr. Wong and my partners for constructive comments and suggestions. This work was supported by Nature Science Research Project, Education Department, Anhui Province, China (grant no. KJ 2012012).ReferenceWilliam P Barber, David C Stuckey. Startup strategies for anaerobic baffled reactors treating a synthetic sucrose feed. Proc 8th International Conf on Anaerobic Digestion, 1997; 2.Grobicki A, Stuckey D C. Performance of the anaerobic baffled reactor under steady-state and shock loading conditions. Biotech and Bioeng, 1991; 37:344-355.Andre Bachman, Virbinia L Beard, Perry L McCarty .Performance characteristics of the anaerobic baffled reactor. Water Res, 1985.Nachaiyasit S, Stuckey D C. Effect of low temperatures on the performance of an anaerobic baffled reactor (ABR).Journal Chem Tech Biotechnol,1997;69:276-284.Cover LetterDear Dr. Arun Gavaskar:Enclosed is a manuscript by Qi Fuzhang titled “Study on the treatment of domestic wastewater by anaerobic baffled reactor”. It is submitted to be considered for publication as a “review in your journal. Neither the entire paper nor any part of its content has been published or has been accepted elsewhere. It is not being submitted to any other journal.We believe the paper may be of particular interest to the readers of your journal.Correspondence and phone calls about the paper should be direc