Treatment Technology Of RO Concentrate Of Landfill Leachate In Long Quan Shan

In the process of municipal solid waste landfill,there will be landfill leachate with complex components.Reverse osmosis membrane?RO?treatment is often used as the last step of advanced treatment of landfill leachate to ensure the quality of effluent.However,with the high salinity and poor biodegradability of the discharged ro concentrate,its treatment and disposal has become a difficult problem in the industry,and reliable solutions are urgently needed.Based on the investigation of the water quality of RO concentrate in Longquanshan landfill of Hefei City,this paper puts forward the treatment of RO concentrate by map chemical precipitation method combined with heterogeneous Fenton technology.During the experiment,the influence of various factors on the reaction is explored by means of XRD,XRF,SEM,XPS,three-dimensional fluorescence spectrum and other characterization means,in which the removal rate of NH₃-N contained in sewage and TOC removal of organic matter are used Rate as a measure.After a series of research and analysis,the following results are obtained:?1?The RO concentrate of landfill has obvious seasonal characteristics,and the water quality in summer is worse than that in spring.The p H of RO concentrated solution is between 6 and 7.With the increase of temperature,the organic components in garbage decompose greatly,and the concentration of COD and ammonia nitrogen increases gradually.In July,the concentration of COD and ammonia nitrogen reached the highest value of 11188 mg/L and 3219 mg/L respectively.With the passage of time,the salinity of RO concentration gradually accumulated,up to 35g/L.the main cation in inorganic salt composition is potassium sodium calcium magnesium ion,which reached the maximum of 3453mg/L,5508 mg/L,635mg/L,587mg/L in July.?2?It was found that the high concentration of potassium and sodium ions in RO concentrated solution of landfill leachate would affect the crystallization of ornithopterite.With the increase of potassium concentration,the recovery of ammonia nitrogen decreased from 96.5%to 83.0%.When the molar ratio of K/Mg in the solution increased from 1:2 to 5:1,the mass percentage of potassium ion in the precipitate increased from 2.4%to 6.4%,but it had no effect on the particle size and morphology of guanosine crystal.The high concentration of sodium ions in the solution will hinder the further growth of guano stone crystal and make the crystal size smaller.In order to ensure the recovery of ammonia nitrogen,the proportion of magnesium salt and phosphate should be increased in the actual ro concentrated solution with high potassium1.8:1:1.5 to ensure that the effluent of ammonia nitrogen and phosphate meets the standard.?3?The Fenton reaction was catalyzed by pyrrhotite,and the reaction conditions werestudied.Considering the economic cost and biodegradability of the treatment,the optimal reaction conditions for RO concentrate with TOC concentration of 1158mg/L are as follows:when p H=2,hydrogen peroxide concentration of 0.5mol/l,mineral dosage of 3g/L,reaction temperature of 25?,the removal rate of TOC in 24h solution can reach more than 70%.The characterization of the solid catalyst shows that the main mechanism is the reaction of iron dissolved in the catalyst with H₂O₂.When pyrrhotite was used to degrade the concentrate for four times under the same conditions,the removal efficiency of TOC was almost not affected,which could reach more than 70%,indicating the recyclability of pyrrhotite in wastewater treatment process and its potential in environmental treatment.