Abstract: Ceramsite(SSA=7.925 m²·g^-1)made from fly ash and wheat straw is often used as filling in biological aerated filter(BAF)for treating municipal sewage and restaurant wastewater,enabling BAF to remove 90.33%,77.44%,82.41% and 86.50%,68.98%,80.30% of COD,NH₃-N,and TP from two kinds of wastewater,respectively.How the used ceramsite from the system could be recycled as resource for agricultural use was once under feasibility study,which was aimed at exploring effects of its use on seed germination,growth,drought-resistance and yield of Brassica chinesis.Results show that the substance meets the standard for use of urban wastes in agriculture(GB8172-87).The treatment of 20% ceramsite in the culture substrate was the highest,reaching 100% within five days,in seed germination rate.The plant grew better with increasing content of ceramsite in the substrate,and its yield showed a rising trend,too.It increased by as high as 352.51%,when ceramsite reached 80% in the culture substrate.However,drought resistance of the substrate was negatively correlated withe the content of ceramsite,and the substrates with 20% and 40% of ceramsite were more capable of preserving soil moisture.

Key words: straw, fly ash, ceramsite, water treatment, filter material, recycling