Phosphate Fixation Performance Of Sludge-based Constructed Wetland Matrix

The implementation of Comrade Xi Jinping’s thoughts on ecological civilization and the implementation of the strategy for the revitalization of rural areas are the current real needs of the country’s rural development.In recent years,great progress has been made in environmental infrastructure and protection in Henan Province.The untreated sewage in the area is directly discharged into the water environment,causing eutrophication of the water and seriously endangering the health and safety of the residents.On the other hand,the treatment and disposal of sludge in water supply plants has been one of the problems that plagued enterprises for a long time.In recent years,the resource development and utilization of sludge has become a research hotspot.The research is based on the research and development of wastewater treatment technology and materials in rural areas of Henan Province,with the goal of improving the operation efficiency of constructed wetland phosphorus removal and the sustainable use of sludge resources in the waterworks.A sludge from a waterworks in Zhengzhou was selected as the main material.The experimental conditions and methods for the preparation of feedwater sludge-based biological ceramsite were analyzed.The performance of preparation of ceramsite was analyzed and analyzed.The adsorption and desorption performance of sludge-based ceramsite on the single preparation of phosphorus-containing wastewater and the raw sewage of sewage treatment plant The characteristics of adsorption kinetics of ceramsite to phosphorus were analyzed and studied.The main research conclusions are as follows:(1)Based on the elemental composition and contained components of the sludge of the water supply plant,based on the comprehensive ceramics production principle and expansion mechanism,bentonite,calcium carbonate,and starch are selected as auxiliary materials for the preparation of ceramsite.Taking the adsorption amount of phosphorus on the finished ceramsite as the evaluation index,the optimal ratio of raw materials and auxiliary materials was obtained through the controlled variable method experiment.The sludge of the waterworks:bentonite:calcium carbonate:starch=86:9:4:1;The pottery process is:the preheating temperature is400°C,the preheating time is 20min;the calcination temperature is 900°C,and the calcination time is 10min.The performance of ceramsite was characterized and analyzed.The SEM image showed that the surface of ceramsite calcined at 900℃had glass-like crystals,many pores,and compact structure.The chemical composition of feedwater sludge powder and ceramsite was obtained by XRF analysis,which provided a reference value for the research on the sintering mechanism of ceramsite.It can be seen from the XRD diagram that the combination of different elements after burning produces a molten product,which increases the mechanical strength of the ceramsite to a certain extent.The heavy metal leaching concentration of ceramsite is far lower than the concentration limit in the national standard"Identification Standard for Hazardous Waste Leaching Toxicity"(GB 5085.3-2007).(2)The adsorption and desorption experiments of ceramsite to phosphorus were carried out.The influence factors of ceramsite’s phosphorus-fixing performance and the characteristics of ceramsite’s adsorption and desorption of phosphorus were analyzed.Neutral acidic environment and higher temperature help to improve the adsorption effect of ceramsite to phosphorus;the chargeability of coexisting ions in the solution has different effects on adsorption and removal of phosphorus,and the coexisting ions NH4~+and NO3~-can inhibit the ceramsite to phosphorus of adsorption.The adsorption process of ceramsite to phosphorus conforms to Freundlich isotherm adsorption model and quasi-second-order kinetic model.The effects of two factors,the height of the packing layer of the adsorption column and the flow velocity of the water on the dynamic phosphorus absorption were investigated through the dynamic column adsorption and desorption experiments of ceramsite.The change of the rate constants of the two models is inversely proportional to the height of the column packing and proportional to the water flow rate.The results of desorption experiments show that the adsorption of phosphorus by ceramsite is relatively stable,and the adsorbed solute can be adsorbed inside the ceramsite more stably.Sludge-based ceramsite has good and stable phosphorus adsorption potential in actual sewage treatment projects.The use of sludge from the water supply plant to prepare ceramsite for resource utilization can reduce the amount of landfill disposal and truly achieve sludge reduction,harmlessness and resource utilization.