PERFORMANCE AND PHOSPHORUS REMOVAL IN MUSKEGON'S WASTEWATER LAND TREATMENT SYSTEM

It is well known that using conventional municipal wastewater treatment systems to remove nutrients (e.g., nitrogen and phosphorus) is very expensive. As an alternative, wastewater land treatment systems could be cost-effective and very efficient for nutrient removal. While wastewater land treatment systems has been used for several decades, we still do not fully understand the effects of long-term wastewater application on (1) soil property changes, (2) phosphorus (P) distributions in the soil, and (3) the life expectancy of a land treatment system. In this study, we evaluated the long-term performance of the Muskegon wastewater land treatment system and investigated the corresponding changes in soil chemical properties and P profiles in both the slow rate (SR) and rapid infiltration (RI) system at the Muskegon plant. The results indicate that the long-term application of wastewater has changed Muskegon's soil chemical properties, such as soil pH and the amount of Ca absorbed by the soil. The soil's P adsorption capacity has increased by 2–4 times and is positively correlated with the concentration of exchangeable Ca in the soil. The life expectancy of the Muskegon's SR system has been extended since 1974. In the RI system, P can be removed very efficiently. The Fe-bound P and Ca-bound accounts for ˜90% of the total P retained in the RI soil. We believe that the exchangeable Ca plays a major role in P adsorption in both the SR and RI system.