再生水回用于景观水体的水质要求探讨

On water quality of reclaimed water for waterscape recharge

再生水回用于景观水体易出现水华,相伴而来的还有卫生学和美学问题。控制氮磷浓度和水力停留时间是预防水华发生的有效措施。我国再生水回用的相关水质标准中对氮磷浓度值的规定偏高,对再生水水力停留时间的规定大于藻类生长的世代周期。对实际水体进行研究发现,这类标准中对氮磷浓度的上限要求并不能有效控制水华的发生。一些再生水回用量大的水体稀释能力差,长期使用会引起营养盐积累,因此建议制定再生水中氮磷浓度的标准时应考虑到这个因素。如果完全以再生水补充的水体,氨氮浓度宜降低到1mg/L以下,总磷浓度宜降低到0.1mg/L以下。

Reclaimed water applied to body of waterscape can cause water-bloom as well as many hygienic and aesthetic problems definitely. It could be available to control the concentration of nitrogen and phosphorus and the hydraulic retention time for algae bloom preventing. The water quality criterion in existing responsible standards about the N and P concentration are too high for waterscape protection, and the hydraulic retention time of reclaimed water in water-body is always longer than the algae growth generation. So these standards are weak to prevent algae bloom effectively. Considering the lower dilution capacity of some water-body, which is recharged by large amount of reclaimed water, the nutrients can be accumulated if the reclaimed water is applied for long time, so the N and P level in the reclaimed water have to be controlled. In case when the waterscape is supplemented fully by the reclaimed water, the concentrations of nitrogen and phosphorus have to be controlled in 1 mg/L and 0. 1 mg/L respectively.