Research For Reverse Osmosis Membrane Concentration Separation Technology Of Biogas Slurry

China is the biggest country of biogas production and consumption, strengthen the use of biogas slurry can enhance China’s industrial competitiveness. The breeding scale and intensification of livestock and poultry brought environmental problems and biogas slurry oversupply problem which seriously restricts the sustainable development of biogas industry. To solve this problem, the effective way is the biogas slurry were resource utilization. That is to explore effective ways of green utilization. In this paper, combined with the national major special sub topic "the reduction of ammonia nitrogen in livestock and poultry breeding wastewater and the technology research and engineering demonstration (2012ZX07202-010)". Using reverse osmosis membrane separation system, analysis biogas slurry composition, determining method of test; analysis the biogas slurry concentration and separation performance; optimization biogas slurry ammonia weaken technology, determine the system optimal operation pressure, pH value, recovery rate; analysis fouling and cleaning scheme. The specific research contents and results are as follows:(1) Introducing the analysis results of reverse osmosis membrane system and related parameters of instrument and testing components of biogas demonstration project.(2) The single factor experiment was used to study the effect of operation pressure, pH value, concentration and recovery rate. In safe operation range, with the increase of operating pressure, COD, NH3-N removal rate increased first and decreased, appropriately increased pressure is helpful to improve the COD, NH3-N removal; neutral and recovery rate of 70% to 80% are more conducive to the removal of COD and NH3-N; Concentration continued to increase in the process, the COD and NH3-N removal rate was decreased.(3) The single factor experiment was used to explore the influence of operating pressure, pH value, concentration and recovery rate. Within the range of safe operation, more pressure on the operation, TN, COD and TP concentration effect roughly increased significantly and then leveled off, NH3-N concentration effect was strengthened and then leveled off last slightly reduced; Increased with pH value and concentration, effect of concentration of COD, NH3-N, TN and TP were first increased and then decreased; With increase of the recovery rate, COD, NH3-N, TN and TP concentration ratio showed an upward trend, increase the recovery rate, TP concentration effect will be better compared with NH3-N, COD, TN.(4) The Plackett-Burman selected operating pressure, pH value and the recovery rate of significant conditions; According to the steepest ascent approximation test to determine the maximum response location for the operating pressure of 5.4Mpa, the pH value is 7.5, the recovery rate of 75%; Optimization of significant conditions using response surface method Box-Behnken, the optimal conditions for the reduction of ammonia are:operating pressure 5.50Mpa, recovery rate 76%, the pH value 7.70, the ammonia nitrogen removal rate could reach 96.13% in the actual process of reverse osmosis membrane; Biogas slurry in the pilot test, ammonia reduction rate value of 94.27%, the pilot test and pilot test of ammonia nitrogen reduction rate error is only 1.93%, Box-Behnken reverse osmosis technology to optimize the response surface method to remove ammonia in biogas slurry is feasible and effective. The concentration of COD in the liquid is 50.99mg/L, NH3-N concentration is 29.22mg/L, which reach the national standard of pollutant discharge and the standard of national farmland irrigation.(5) Qualitative analysis of the reverse osmosis membrane fouling, determine mainly carbonate fouling and microbial contamination; In the choice of cleaning test scheme, the test first with composite cleaning agent of 0.1% NaOH and 0.025%Na-SDS microbial removal of pollutants, then with 0.2% acid salt carbonate removal method, can make the desalination rate of recovery rate and membrane flux recovery rate as high as 13.90%,8.71% respectively; In the cleaning time is 2h, desalination rate reached a maximum value of 94.4%, the membrane flux returned to 61.69L/m2. H. This test should be maintained at about 2h.