RECYCLED BRICK AND CONCRETE AGGREGATES FROM CONSTRUCTION AND DEMOLITION WASTE MIXED AS SUBSTRATES IN CONSTRUCTED WETLAND FOR TREATMENT OF MICRO-POLLUTED WATER AND ITS APPLICATIONS
To improve the purification capacity of recycled aggregates from construction and demolition waste for actual micro-polluted water,a mixture of recycled brick aggregate(RBA)and recycled concrete aggregate(RCA)in two proportions was used as substrates to construct two vertical flow constructed wetland(VFCW)systems,namely CW1(80％RBA+20％RCA)and CW2(50％RBA+50％RCA).A control group with natural aggregates(zeolite,lava rock,limestone)as substrates was set up.The results showed that the TP removal efficiencies during the stable operation period of CW1 and CW2 were 57.5％and 42.7％,respectively,which were 38.9％and 24.1％higher compared to the control group.The NH3-N,TN,and COD removal effect of CW2 with an increased proportion of RCA was close to that of the system with natural aggregates,with removal efficiencies of 70.2％,16.9％,and 63.5％,respectively,achieving the effect of treating pollution with waste materials.The calculation of the Nemerow pollution index further demonstrated that increasing the proportion of RCA was conducive to improving the comprehensive pollution control efficiency of the systems with recycled aggregates,which was better than the systems with traditional natural aggregates.The environmental risk assessment indicated that the environmental risk level of effluent each pollutant in the recycled aggregate systems during the stable operation phase was at a desirable level,with a low impact on the receiving water.The economic analysis showed that the CW2 had the lowest cost and significant benefits.The VFCWs using a mixture of 50％RBA and 50％RCA as the substrate was successfully applied in the Wenyu River Wetland Park in Beijing.When the influent water quality exceeded the limit of the Class Ⅳ of Environmental Quality Standards for Surface Water(GB 3838-2002),the effluent NH3-N,TP,and COD of each outlet point all met the Class Ⅲ water quality standard.
construction and demolition wasterecycled aggregatesvertical flow constructed wetlandwater purificationdemonstration applications
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