Ammonia Stripping Process Of Aquaculture Wastewater And Treatment Of Denitrification Biogas Slurry

The rapid development of the livestock and poultry breeding industry has put forward urgent requirements for the efficient management of livestock and poultry manure.So large and medium-sized biogas projects have developed rapidly.However,what follows is a large amount of biogas slurry rich in nitrogen and phosphorus content,which need to be properly treated to avoid air pollution and water pollution.Ammonia stripping is a simple treatment method of the characteristics of low-investment,wide-ranging ammonia recovery,which can be easily combined with existing biogas projects to process biogas slurry.Based on the removal of ammonia from the biogas slurry,this paper focuses on the removal of ammonia nitrogen from the biogas slurry and the utilization,secondary treatment of the biogas slurry after the stripping.(1)The effects of three variables,such as the volume of stripping,temperature,and gas flow rate on ammonia nitrogen removal in the biogas slurry and characteristics of biogas slurry were studied.Ammonia nitrogen removal efficiency increases with the increase of stripping temperature and air flow rate under different volume conditions,however the effect of temperature on ammonia removal under different stripping volume conditions is different.When the stripping volume was increased to 30 L and 50 L,the final removal rates were only 56.7% and 57.7% at 55 °C and 800 L/h for 24 hours.And the ammonia nitrogen removal rate was significantly improved compared to 55 ? when the stripping temperature was increased to 75 ?,with the maximum removal rate reached 88.1% and 91.2%,respectively of the 30 L and 50 L stripping volumes.In addition,the concentration of biogas slurry,COD value,and p H are different under different volumes,which be higher with low volume conditions.(2)Ammonia stripping scheme was subsequently designed with the operating cost of the removal of 85% ammonia nitrogen from 200 t of biogas slurry,calculated for the biogas project of 10,000 pig farms.It is predicted that it is required for the conditions of 75 ? and gas-liquid ratio of 450 to achieve 85% ammonia nitrogen removal rate based on a kinetic model established by previous test data.Then the operating cost of the designed ammonia stripping scheme was analysised through this stripping parameter.It is found that the cost of processing 200 t of biogas slurry per day is 2062.3 RMB,which equivalent to 10.3 RMB/t.And the heating cost of the biogas slurry accounted for 86.4% of the total cost in the stripping tower,while the acid absorption accounted for 11.1% of the total cost.At the same time,the amount of ammonium sulfate finally obtained 9.18 t after the treatment of 200 t biogas slurry and 85% ammonia nitrogen removal rate.(3)Biogas slurry can be recycled in anaerobic digestion system with pig manure as a substrate after stripping.It's found that the biogas slurry can reduce biogas yield and degradation rate when recycled to AD after stripping.However,this situation can be optimized by using rice husk biochar and scrap iron.The results show that the biogas yield was improved significantly with the addition of rice husk biochar and scrap iron when the biogas slurry is recycled.The highest cumulative biogas yield was 292.6 ml/TS*g(9 g/L),increased 33.5%,and the cumulative methane yield was 1.5 times that of the control group.The highest cumulative biogas yield increased by 20.7% with the addition of 9 g/L biochar.(4)The biogas slurry also can be re-concentrated through a ceramic membrane filtration system after the ammonia stripping.The biogas slurry should be pretreated to ensure the membrane flux during ceramic membrane filtration before the membrane filtration.The ammonia nitrogen concentration in the biogas slurry was reduced again after biochar and PAC pretreatment.The effect of PAC on reducing ammonia nitrogen was not significant while the adsorption effect of biochar on ammonia nitrogen was better.The ammonia nitrogen concentration was reduced to 66.1 mg/L in biogas slurry,and the removal rate is 64.08% after 5 g /L adsorption of biochar.The removal rate of total phosphorus can reach 81% contributed by PCA,while the contribution of biochar is not significantly in total phosphorus removal rate.There is a low removal effect on suspended solids and turbidity in biogas slurry with biochar,resulting in a lower membrane flux during subsequent membrane filtration.The combined pretreatment of biochar and PAC can comprehensively remove various indicators in biogas slurry while ensuring that membrane flux during membrane filtration.The COD removal rate and turbidity removal rate reached 81% and 96% when the biogas slurry was pretreated with biochar and PAC and then filtered through a ceramic membrane.