Sutdy On Nitrogen And Phosphorus Recovery From High-speed Train Toilet Sewage

From 2008,rapid development of high-speed trains in our country has brought about some problems that need to be solved urgently.How to recover nutrient elements from high-speed train toilet sewage contained high concentrations of nitrogen?N?,phosphorus?P?,suspended solids?SS?and organic matter is especially problematic.Therefore,the wastewater from the toilet of the high-speed rail in this reaserch was used as the research object for recovering phosphorus by ammonium magnesium phosphate crystal precipitation,and recovering nitrogenby stripping is import.This study compared the advantages and disadvantages of the recovery of phosphorus from raw water and anaerobic effluent by ammonium magnesium phosphate method.The effects of the initial pH,n?Mg?:n?P?,and reaction time on the recovery of phosphorus and the purity of the recovered phosphorus were investigated.Fourier transform infrared spectroscopy?FT-IR?,X-ray diffraction analysis?XRD?and scanning electron microscopy?SEM and EDAX?are applied to phosphorus recovery products.After anaerobic treatment and phosphorus removal by magnesium ammonium phosphate,the air stripping is used to recover the high concentration of ammonia nitrogen in the water.The effects of stripping time,gas flow,temperature,and initial pH on ammonia nitrogen removal rate were investigated.Experimental results haved shown that the removal rate of SS is as high as 97%,and the concentration of dissolved orthophosphate is increased by 92.65%by anaerobic pretreatmen.Magnesium phosphate magnesium method was used to recover phosphorus for the raw water and anaerobic pretreatment effluent.The experimental results show that the The highest recovery of phosphorus in raw water was only 85.20%,and the remaining orthophosphate concentration was 13.04mg×L^-1.The recovery rate of phosphorus in anaerobic pretreatment effluent was up to 96.71%,and the remaining orthophosphate concentration was only 2.35 mg×L^-1under the conditions of n?Mg?:n?P?=1.4,reaction initial pH=9.0 and reaction time 6.0 min.Fourier transform infrared spectroscopy?FT-IR?,X-ray diffraction analysis?XRD?,and electron microscopy?SEM and EDAX?analysis haved showed that the phosphorus recovery product was very much available as magnesium ammonium phosphate crystals.That mass fraction greater then 30%after converted to P₂O₅ can be used as industrial phosphate rock.The optimal operating conditions for ammonia nitrogen stripping were initial pH12,time 100 min,gas flow rate 320 L×h^-1,and temperature 70°C.Under optimal conditions,the ammonia nitrogen stripping rate was 95.40%and the residual ammonia nitrogen concentration was 57.36 mg/L.When the dilute sulfuric acid was used to absorb time was within 16 h,the absorption rate of ammonia nitrogen was close to99.93%.When it was 48 h,the primary absorption bottle was saturated.