Investigation On The Treatment Of The High Ammonium-nitrogen Biogas Slurry Wastewater By The Method Of Membrane Process

In recent years,livestock and poultry breeding industries developed rapidly in our country.There is no biogas project for older livestock and poultry breeding farm,or the treatment capacity of biogas project is below the scale of breeding,which thus resulted in the producing of a lot of high-ammonia nitrogen and organic biogas slurry wastewater in these livestock and poultry breeding farms.Indiscriminate discharging of these biogas slurry wastewaters brought serious water pollution around the farm.So it is imperative to develop multifaceted treatment technology.In this paper,membrane adsorption and membrane reactor were used to dispose the biogas slurry wastewater.Polyvinylidene fluoride(PVDF)hollow fiber membrane applied to the treatment of biogas slurry wastewater in membrane bioreactor was prepared by the method of phase inversion using polyvinylidene fluoride resin.The influence of PVDF content,additive amount of associative pore-forming agent and spinning condition,which included the extruded velocity of PVDF casting solution,winding speed of membrane fibers and bore flow rate on the structure and performance of PVDF hollow fiber membranes was investigated.Optimized preparation conditions were obtained: the PVDF casting solution is composed of 22wt% PVDF,71wt% DMAc solvent and 7wt% pore forming agent.The spinning conditions are that the spinning solution temperature and external coagulating temperature were 30 and 25,respectively.And the extruded velocity of PVDF casting solution and winding speed of membrane fibers and bore flow rate was 23r/min,28 r/min and 4ml/min,respectively.Polytetrafluoroethylene(PTFE)hollow fiber module was prepared by encapsulating hydrophobic PTFE hollow fiber membrane in the membrane shell.The membrane adsorption was used to remove the ammonium-nitrogen in the biogas slurry wastewater.The effect of pH value of biogas slurry wastewater,adsorption concentration and flow rate of biogas slurry wastewater on the removal of ammonium-nitrogen was investigated.When the pH value of biogas slurry wastewater,adsorption concentration and flow rate of biogas slurry wastewater was 11,0.2mol/L and 6.0-6.5cm/s,the removal rate of ammonium-nitrogen in the biogas slurry wastewater reached its maximum.Treated by membrane adsorption for 400,600,800 and 1000mg/L four biogas slurry wastewater,the limitation concentration of ammonium-nitrogen could be low to 17-51mg/L.According to the characterization of biogas slurry wastewater,high pollutant concentration and low C/N ratio,a anaerobic/aerobic/MBR integrated process was designed to treat the biogas slurry wastewater in which the ammonium-nitrogen was removed by membrane adsorption.The effect of treatment of anaerobic/aerobic/MBR integrated process for the COD,ammonium-nitrogen,TP and SS was investigated.The operating effect of three months proved that the integrated process showed good removal efficiency for COD,ammonium-nitrogen,TP and SS in the biogas slurry wastewater.The value of COD,ammonium-nitrogen,TP and SS in the draining water reached 200mg/L ? 10 mg/L ? 5 mg/L and 20 mg/L,respectively.The draining concentration is far below the value of the discharge standard of pollutants for livestock and poultry breeding(GB18596-2001).At last,we had the anaerobic/aerobic/MBR integrated process enlarged and tried to fabricate equipment.An integrated equipment prototype with daily treatment capacity of 3 tons was fabricated.