PHOSPHORUS REMOVAL USING PASSIVE AND LOW MAINTENANCE TECHNOLOGY

Phosphorous contributions from wastewater is the major cause of water quality deterioration in many parts of the US. Some soils have limited capacity to remove phosphorous and in some areas the capacity is consumed within a few years. Phosphorous concentrations above 0.03 – 0.05 ppm cause excessive algae growth with the associated water quality degradation. Wastewater phosphorous concentrations are typically 3 – 7 ppm so that 99 % phosphorous removal is necessary to minimize the impact of wastewater contributions on water quality.Wastewater phosphorous removal technologies for small-flow applications have been very limited and have, to date, been characterized by excessive operational requirements that have made them impractical for widespread application.The PHOSPHEX™ and PhosRID™ patented phosphorous removal technologies have been developed and tested by independent parties. The PHOSPHEX™ technology uses an iron slag media and high pH has been demonstrated to be consistently capable of reducing wastewater phosphorous levels to less than 0.07 ppm for over five years of field testing and nine years of laboratory testing. Fecal coliform and E. coli levels have been reduced by approximately 2 logs. The longevity of the PHOSPHEX™ filter is estimated to be 10 – 20 years with few operation and maintenance requirements. Due to cost considerations, the technology is better applied at larger flow or high unit cost sites.The PhosRID™ technology, which uses an iron-based media, has been demonstrated to be capable of reducing wastewater phosphorous levels to less than 0.100 ppm. The longevity of the PhosRID™ filter is a design issue and can be 5 – 15 years with few operation and maintenance requirements.The paper will present a description of independent performance evaluations of the PHOSPHEX™ and PhosRID™ phosphorus removal systems in North Bay, Ontario and Cape Cod, Massachusetts.