Applied Research On Treatment Of Piggery Wastewater By UASB Reactor

The wastewater of swine have become the main pollution source in manydistricts of China.With living standards continued to increase,the intensive breedingindustry will go on development and will inevitably produce more pollution in thenext years.Swine wastewater can be treated by three modes:landspreading,ecological mode and engineering treatment.But in developed area populous,becauseenvironment and land is limited,engineering treatment has to be chosen as the onlymode.In the engineering treatment,if raw swine wastewater is treated directly with anaerobic process,running cost are very high,so anaerobic-aerobic process is generallyadopted. As the typical represent of second generation anaerobic processes, UASB isused in this swine wastewater treating project. The article made a thoroughly studyand analysis on starting period and influencing factors of the process, in addition, itmade a detailed analysis on the question which appeared in the debugging of UASB,and sumed up the solutions. The research suggests that:(1)Before swine wastewater entering UASB reactor, the most important task ofpre-processing is remove the suspended substance from wastewater. The concentrationof suspended substance should less than 2g/L,or not more than 4 g/L;(2)During the starting of UASB reactor, two mothods of increasing volumeload are usually adopted.Increase rate of early starting is not more than 0.5kgCOD_Cr/(m³Â·d); at the stage of emerging and cultivating granular sludge,the increaserate is not more than 1.0 kgCOD_Cr/(m³Â·d). Using this mothod of high frequency andlow rate, we can achieve the aim of shartening the period of debugging;(3)Hydraulic retention time(HRT) should be gradually reduce,and the projectis divided into three stages:110 hours,62 hours and 42 hours. For a UASB reactorhave no cycle pumps, hydraulic retention time directly determines hydraulic load,sochoosing a suitable reduce rate is very important;(4)With the debugging of UASB reactor, temperature is one of the key factors.When the project have no measures to insulate or heat, choosing the right season also defining the debugging in some degree;(5)When the UASB reactors operate stably, the averate removal rate of COD_Cr isabout 80%,and the averate water exit COD_Cr concentration is 1562.5mg/L; the averateremoval rate of NH₃-N is -8.77%,in other words,thourgh the UASB reactor, theconcentration increased,and the averate water exit NH₃-N concentration is958.71mg/L.The result of the study above provides a technical references for the swine wastewater using UASB reactor ,and has reference significance to solve the treatment ofswine waste water or livestock and poultry waste water which is similar to swinewaste water.