| In recent years, the intensive livestock farming methods development rapidly as China’s agricultural structure adjustment and the advance of the agricultural industrialization, and the resulting that the biogas slurry pollution environmental issues can not be ignored. The biogas slurry is the residual liquid from livestock manure through anaerobic fermentation, although contains rich plant nutrients, such as nitrogen and phosphorus, but also will cause great harm to the environment by field directly. Adsorption treatment method has played an important role in the utilization of biogas slurry standard treatment and high values of biogas slurry as an important branch of the biogas processing.So, this test uses a combination of static and dynamic assay methods, filters out the better of the adsorbed materials from coconut shell activated carbon, nut shell activated carbon, coal activated carbon, natural zeolite and natural montmorillonite, and by dynamic assay, ups to standard as precondition, screenes the group which processes the biogas slurry largest volume.Adsorption isotherm experiment shows that the largest amount of saturated adsorption of TP from coal activated carbon and coconut shell activated carbon, are1741.55,1545.12mg/kg. For NH4+-N and TN, the maximum adsorption amount sequentially are all zeolite and montmorillonite, are8110.30,7501.875mg/kg and8952.26,7315.29mg/kg. The adsorption of COD, activated carbon has a larger advantage, the first is coconut shell activated carbon, is25510.20mg/kg. Adsorption kinetics experiments shows that, for the same indicator, there is little difference between the times of the adsorbent material to reach equilibrium, TP is between120-250min, NH4+-N is about150min, for TN, montmorillonite is the fastest one who reaches equilibrium, only takes120min, the rest are about230min, COD’ equilibrium is about180min.Reference the saturated adsorption capacity and adsorption equilibrium time of adsorption material for various indicators, finally screens coconut shell activated carbon(Y), coal activated carbon (M) and natural zeolite (F) which are favor adsorpt the nitrogen and phosphorus in biogas slurry. The experiments show that the advantage of zeolite adsorpt nitrogen in wastewater is in lower nitrogen concentration as a precondition, the nitrogen concentration is too high, not only does not promote its zeolite adsorption, but also will dampen demand. When the volumetric loading is4.8cm3/(cm3·min), the individual adsorption column tests get the dynamic adsorption capacity show:coal activated carbon adsorption column’dynamic adsorption capacity of TP and TN are the largest, are75.04,444.54mg/kg, the largest dynamic adsorption capacity of NH4+-N is coconut shell activated carbon adsorption column, is370.67mg/kg. For the joint adsorption column tests, the largest the dynamic adsorption capacity of TP and NH4+-N is Y-M-F, are76.39,583.05mg/kg. M-Y-F’dynamic adsorption capacity of TN is largest, is757.19mg/kg.According to pollutant emission standards for livestock and poultry breeding industry(GB18596-2001), to reach the standards of each indicator as a precondition, studys the process biogas slurry amount of each group, the descending order of each group with processing the biogas slurry amount is:Y-M-F>Y-F-M>M-Y-F>M-F-Y> F-Y-M>F-M-Y, the largest amount of process the biogas slurry is Y-M-F, the coconut shell carbon activated carbon-coal carbon activated carbon-zeolite, the amount of processing the biogas slurry is198mL/mL(V1/V2, Vi is water treatment amounts,V2is adsorption column volume).The problems of the adsorption matrix fewer types and weak processing capability exist in this test, pending further research. |
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