| With the development of economy, the increasing growth of population and pollution of water environment increasingly heavier, make our country and even the whole world is facing the problem of water resources shortage. Because of domestic sewage, industrial sewage emissions reduce the utilization rate of water resources. Wastewater reclamation and reuse in certain use range, which provides an economic and reliable new water resource, and can save quality of drinking water resource. Secondary effluent of city sewage treatment plant after the regeneration treatment is the important water supply of landscape and ecological river. But for secondary effluent contains a large amount of nitrogen, phosphorus and water soluble organic, after the regeneration treatment added landscape water will still have the potential ecological risks. So, this paper based on secondary effluent as raw water, depth treatment nitrogen, phosphorus and water soluble organic from secondary effluent by the coagulation-adsorption. Studied pollutant removal efficiency by coagulation-adsorption, to select the best removal methods of nitrogen, phosphorus, water soluble organic from secondary effluent. The main conclusions of the paper are as follows:1Secondary effluent treated by coagulation, aluminum sulfate and polyacrylamide combined use as coagulant. The best dosage of coagulant is112mg/L. Coagulant appropriate pH range is6.0～7.0, neutral and weak acid. Firstly coagulation stirring speed in250r/min rapid mixing, then mixing speed continue with90～125r/min.2According to the determination of the best condition of coagulation, coagulation effluent total phosphorus removal rate reached96.30%, total nitrogen and ammonia nitrogen removal effect is poorer. UV254, Dissolved Organic Carbon (DOC), COD removal rate are76.60%,76.05%,42.80%; COD can achieve the recycled water landscape reuse standards.3Secondary effluent treated by active carbon adsorption and zeolite adsorption. The best dosage of activated carbon and zeolite were30mg and120mg when adsorption equilibrium. Zeolite adsorption effluent total nitrogen, ammonia nitrogen removal rate are59.10%,82.86%; UV254, DOC removal rate are61.28%,91.46%. Active carbon adsorption total nitrogen concentration is21.80mg/L, ammonia nitrogen concentration gradually resolved out with time. UV254, DOC removal rate are86.17%,96.41%. Because of two adsorbent contain small amount of phosphorus, total phosphorus concentration of the two adsorption were higher than secondary effluent total phosphorus concentration.4Secondary effluent treated by the coagulation-adsorption. Coagulation effluent treated respectively by carbon adsorption and zeolite adsorption. Zeolite adsorption effluent total nitrogen, ammonia nitrogen concentration are12.94mg/L,3.25mg/L and removal rate are 43.47%,59.22%. The value of UV254with the extension of time but increasing, DOC removal rate reached60.76%. Active carbon absorption effluent total nitrogen removal rate is only5.90%; ammonia nitrogen adsorption is not firm and quickly resolve. The value of UV254is2.40m-1, removal rate reached77.78%. The removal rate of DOC with the extension of time continues to increase. Zeolite adsorption equilibrium time is short. Two kinds of adsorption total phosphorus concentration was slightly increased, but far less than the landscape of reclaimed water reuse standard, does not affect the quality of effluent5Coagulation-zeolite adsorption effluent total phosphorus, total nitrogen, ammonia nitrogen removal rate are87.04%,86.17%,65.20%, good effect of removing, reached the landscape of reclaimed water reuse standard. UV254, DOC, COD removal rate are69.15%,90.60%,43.24%. COD can achieve the recycled water landscape reuse standard. So, using Coagulation-zeolite adsorption disposal technology to remove nitrogen and phosphorus from secondary effluent, provide technical support for the optimization of reclaimed water treatment process and ensure the security of reclaimed water quality. |
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