Characterization Of COD Components In Livestock And Poultry Wastewater And Its Potential Application In Engineering Practice

With fast intensive and large-scale development of livestock and poultry breeding in China,environmental pollution became increasingly serious.Poultry wastewater is a kind of high concentrated organic wastewater,containing feces,urine,farming irrigation water,etc.,which is rich in nitrogen and phosphorus.And is one of the main source of water pollution in rural areas.Because of market risk and meager profit,anaerobic fermentation was widely employed in aquaculture wastewater treatment,yet high concentration of organic matter,nitrogen(N)and phosphorus(P)were contained in livestock and poultry manure by anaerobic fermentation.Biogas slurry has the characteristics of high ammonia and nitrogen,difficult to biodegrade,low C/N which make anaerobic fermentation technology can not meet the livestock and poultry industry pollutant discharge standards.So how to improve the existing process and develop more efficient processing technology is currently focused on livestock and poultry wastewater research.In this study,large-scale pig farm wastewater was taken as the research object.Using standard methods for COD characterizations to charactrize raw water and biogas slurry of pig farm wastewater,for quantitative calculating the COD content in piggery wastewater.So we can better understand the composition of piggery wastewater.The respiromentry experiments of three livestock and poultry farms' raw wastewater showed that the ratio of biodegradable COD components to total COD was 27%~39%,the ratio of soluble inert COD components to total COD was 11%~14%,the ratio of particulate inert COD components to total COD was 11%~14%.The respiromentry experiments of biogas slurry showed that the ratio of biodegradable COD components to total COD was 8.2%~20.2%.Ammonia nitrogen content in biogas slurry reached 753~1134mg/L,which made the slurry difficult to be degraded.And the ratio of inert COD components(SI+XI)to total COD was 75.6%~79.1%.The results of BMP test showed that the amount of methane produced by anaerobic fermentation was positively correlated with the organic load in a certain range,and the higher the load,the higher the methane production.In addition,the temperature,pH,ISR ratio will affect the gas production,when pH is 7.5 the gas production is 199.5mL/gCOD higher than the pH is 8.5 which is 158.1mL/g COD.Therefore,the conditions of anaerobic fermentation should be adjusted in engineering applications.The above experimental analysis shows that the content of inert components(XI + SI)in the raw water accounts for a large part of the total COD,which is the main reason for the poor performance of the biological treatment process.And after biogas treatment,the biodegradable components in the effluent are reduced and the content of the inert components is increased.So the addition of flocculation and advanced oxidation prior to anaerobic fermentation can effectively remove some of the inert components that are difficult to degrade.And the same pretreatment process can be used to remove this part of the refractory component for the particulate inert component of the biogas slurry.For high concentrations of ammonia in biogas slurry can be used zeolite adsorption or short-range nitrification and denitrification-anaerobic ammonium oxidation process to remove.