On-site treatment systems: Biological treatment and nutrient removal

On-site technologies can range from compost privies in national forests to high-tech, membrane-filtration systems that recycle wastewater for toilet flushing in large buildings to sophisticated, yet elegant designs that use ecosystems, such as constructed wetlands, to treat wastewater. This chapter describes the evolution and evaluation of on-site technologies and the factors affecting their performance, as well as case studies of on-site wastewater treatment systems. On-site treatment systems are predominantly suitable for semi-arid and arid regions and for regions that require riparian groundwater recharge, restoration, an increase in surface water flow, irrigation of nearby landscapes or on-site fire control storage. The known nutrient removal approach is the use of biological treatment systems. The chapter focuses on biological nutrient removal of on-site wastewater treatment system. Some of the important factors affecting biological nutrient removal include mean cell residence time (MCRT), aeration requirements, wastewater characteristics, and hydraulic retention time.