(79b) New Trends in Recovery of Nutrients from Point and Distributed Sources

The use of biological systems for removing nitrogen and phosphorus from used water. These systems are used in some form or another universally. Nitrogen is mostly returned to the atmosphere, but phosphorus can be recovered as struvite or some other re-usable product. The latest research concerns a better understanding of biological phosphorus removal to make the process more reliable to cope with varying wastewater characteristics as influenced by seasonal temperature and rainfall. The present quest is for cost-effective retrofitting of existing plants to remove phosphorus to very low levels. However, achieving greater efficiency at point sources does not solve the major problems of plant nutrients from agricultural run-off, reaching lakes and estuaries. Efforts are made to grow and harvest algae as a means of removing these plant nutrients from receiving water which could result in energy recovery.