| The pollution of poultry runoff in rural areas is an important part of non-point source pollution in rural areas.Because of its difficult to control,the impact on water environment is becoming more and more important.It is important to find out the pollution characteristics of this kind of runoff and carry out simple and efficient run-Practical significance.As a traditional low impact development(LID)technology,the bioretention pool has the characteristics of simple structure,effective handling and easy dispersion.It is one of the feasible methods to deal with the contamination of runaway poultry.This paper investigates the characteristics of the runoff pollution of poultry,and carries out the laboratory and field test of the biodetention pool.The main work and conclusions are as follows:(1)Self-built chicken coops were sampled and tested by artificial rainfall test to study the runoff of main pollutants in runaway poultry runoff,and the influence of rainfall characteristics was analyzed preliminarily.The results showed that the mean value of the incident event concentration(EMC)was higher,and the mean values of CODMn,TN,TP and NH3-N were 1.75,12.45,7.5 and 3.35 times higher than those of the V class.TSS exceeding 11.46 times the effluent discharge standards,total nitrogen and total phosphorus are the main pollutants.Runoff contaminants have a weak initial scouring effect,the initial scour ratio FF20 is about 1 to 1.5.The effect of total rainfall and rainfall intensity on the characteristics of runoff pollutants was significant,which was negatively correlated with the concentration of pollutants and had a significant positive correlation with the initial erosion ratio.The longer the number of sunny days,the higher the TP concentration in the runoff,and the correlation between the other pollutant concentration and the number of sunny days.(2)According to the characteristics of runoff pollution of poultry in rural areas,the biological detention column was constructed indoors,and the simulation test of runoff treatment was carried out.The results showed that the removal efficiency of CODMn,TN,TP and NH3-N reached 60%,65%,50%and 70%respectively after 30 days of operation.When the hydraulic load increases from 0.5 m3/(m2 · d)to 2.5 m3/(m2 · d),the pollutant removal rate fluctuates with the hydraulic load and decreases overall.When the hydraulic load is 1.5 m3/(m2 · d),the runoff and pollutant removal rates are high.Considering the handling capacity and the treatment effect,the hydraulic load of the biological detention tank is determined to be 1.5 m3/(m2 · d).(3)A collection and processing system was built around the outdoor chicken coop to verify the effectiveness of the biological detention pool in practical engineering applications.The results showed that the average removal rate of CODMn,TN,TP,NH3-N,SS and BOD5 was 66.3%,71.2%,87.7%,respectively,and the removal rate of conventional pollutants in the runoff was 6.6%%,40%,93.6%and 65.7%respectively.The removal rates of CODMn,TN and BOD5 were close,but the TP and NH3-N removal rates were different.The average removal rate of TP in indoor test was only 32.7%,which was much lower than that of outdoor experiment(87.7%).NH3-N average removal rate of 68.2%,higher than 40%of outdoor experiments,the main reason for this phenomenon is indoor and outdoor test water quality,hydraulic load difference.In different rainfall events,the higher the average concentration of CODMn,the higher the removal rate of NH3-N and the smaller the removal rate of NH3-N.In a rainfall process,the removal rate of each pollutant and the influent concentration of the trend is basically the same.The results of indoor and outdoor experiments show that the bioretention pool is an effective measures for the management of poultry runoff in rural areas. |
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