2008 Joint Annual Meeting (5-9 Oct. 2008): Long-term Biosolids Application to Three Sites in Texas.

Long-term Biosolids Application to Three Sites in Texas

Charles E. Pehl, Sam E. Feagley and James B Akin

K-3 Resources, LP currently manages three sites in the Texas Gulf Coastal Plain permitted for land application of biosolids generated by wastewater treatment plants in the Houston metropolitan area. Annual compliance data for the last five years have been used to evaluate the biosolids applied and the impact on soil conditions for the three sites. Based on this information, biosolids recycling has resulted in an observed increase organic matter content which should stimulate soil microbial activity, improve soil structure, soil aeration, soil water holding capacity, and fertility. Biosolids pollutant concentrations (mg/kg) and soil pollutants levels (kg/ha) remain below 40 CFR 503 criterion. Because biosolids pollutants applied to both sites have been reduced to trace levels and pathogens controlled through technology and regulations, Houston metropolitan area biosolids are a viable source of available N and P for agriculture. However, as with any other organic or industrial fertilizer, biosolids when applied intensively may become a non-point source for nitrate or P pollution. Excessive nitrates can leach into groundwater; P can be a potential threat to surface waters when dissolved in runoff or transported by erosion. Implementing a nutrient management plan will minimize both potential dangers.