分散式污水处理系统流程,设计,管理,使用.pdfVIP

Decentralized Wastewater Treatment Systems: Processes, Design, Management, and Use Sponsored by the Watershed Management Program at Purdue University, the Conservation Technology Information Center, and US EPA 1 Session 1 Overview of Decentralized Wastewater Treatment Barry Tonning, Tetra Tech 2 Overview of Decentralized Wastewater Management Issues • Summary of wastewater management issues • Treatment approaches • Management considerations • Water resource management context 3 Wastewater Management Issues 4 Condition of U.S. surface waters • Pollutant-impaired waters include : – 45% of assessed rivers and streams – 47% of assessed lake acres – 32% of assessed bay and estuarine square miles • Polluted (nonpoint) runoff is mostly to blame • Chief causes are nutrients, pathogens, and sediment 5 Wastewater pollutants of concern • Pathogens – bacteria viruses mainly; plus protozoa, worm eggs • Nitrogen – causes algal growth in nitrogen-limited (mostly coastal) waters; nitrate can cause “blue baby” syndrome • Phosphorus – causes algal growth in P-limited (mostly inland fresh) waters • Others – pharmaceuticals, cleaners, solvents, other toxics (most of which affect treatment processes) 6 Wastewater treatment • What are the options? – Individual onsite (“septic”)