| With the urbanlizetion process expanding, small towns get great developments. But few of small towns have consummate wastewater collecting and treating establishment, and the water entironment in these small towns are facing challenge which is bigger than ever before.the wastewater treatment of small towns has been another study focus after the wastewater treatment of big city. On the other hand, compared with big city, small towns has the characteristic of thinner economy base, and lack of wastewater treatment manger.so we shouldn't apply the wastewater treatment techcnics of big city mechamically on the wastewater treatment of small towns.it's our duty to study and develop simple and wastewater treatment technics that suit small town, which should be simple, economical and effectively.In this paper,study was presented on small town domestic wastewater treatment by using the connective process of Baffled Biological Aerated Filter(BBAF)and oxidation pond.The experiment place is xinsheng town wastewater treatment plant.the experiment period can be divided into two phases.In the first phase, the connective process was runned in the continuous aeration mode.and in the second phase, some changes was made to the process to suit the wastewater in this town. The connective process was runned in intermittent aeration mode to save enegy.At the start-up phase,we studied two kinds of start-up mode,which were inoculate start-up and natural strat-up.from the experiment result we know that the inoculate mode need 12days to achieve strat-up.which was less than the time of natural mode,15 days.which means that inoculate strat-up mode is quicker than natural strat-up mode.In the continuous aeration phase, we study the influence of HRT to the treatment effect of BBAF.the result was:when concentration of effluent were:COD 115～156mg/L,NH3-N 17.90～32.09mg/L,TN 25.60～37.89mg/L,TP 1.69～2.53mg/L,and the the water equality of outflow when HRT=6h is better than other two conditions,which can meet the discharging criterion. Additional,we got from the experiment that in the condition of inflow load 0.85 kgBOD/(m3·d),the air-water ratio 8:1,the treatment efficiency increased when the temperature rise,and even in the lowest temperature(11℃),the treatment efficiency of COD,ammonia and total nitrogen can reach 78.3%,72.5% and 28.7% respectively. The water quality of outflow can reach the need of relative discharging criterion. In the intermittent aeration phase, study was made to make sure the effluence of intermittent aeration and air-water ratio to the treatment effect of connective process. Through the experiment we find the optimal running mode,which is :runned in the air-water ratio 9:1,in the mode 1.25h (aeration)- 1.25h (stop aeration),the treatment efficiency of connective process can reach 88.9%(COD),90.2%(ammonia) and 40.9%(total nitrogen).the outflow water quality can reach the discharging criterion for the wastewater treatment plant of city and town. During the whole experiment period, we find the removal efficiency of total phosphorus was not so good. And sometimes the total phosphorus concentration can't reach the criterian, so it should be improved through other methods.Through the study we kown: when the connective process incurred water quantity strike, the pollution concentration of outflow rise little and the water quality is quite well; when it incurred sudden power cut, the connecitive process can resume its treatment efficiency in nine hours after power supply.from abovewe kown that the connective process has strong ability of enduring stike load and vigor resuming.In addition, we presented the study on back wash of BBAF, and conclusion was got that: we adopt the back wash mode of first air washing(wash intensity 1.5～2 L/(㎡·s),time 5 mins), then air-water washing(air wash intensity 1.5～2 L/(㎡·s),water wash intensity 3.74 L(/㎡·s),time:3～4mins), in the end water washing(wash intensity 3.74 L/(㎡·s),time:1～2 mins),the effect is good,and the back wash cycle can reach three days;the back wash has impact to the outflow of both BBAF and connective process.after back wash the connective process need six hours to resume its treatment efficiency.
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