Monitoring Data

Biosolids Usage

2012 Biosolids Usage

Biosolids generated at the Southwest Clean Water Plant meet the most stringent federal and state regulations for pollutants.

Table 1: Biosolids Pollutant Levels and Regulated Limits




2013 SWCWP Biosolids Avg mg/kg

US EPA & MoDNR Regulation Limits

Exceptional Quality


US EPA & MoDNR Regulation Limits

Ceiling Concentration


Arsenic <4 41 75
Cadmium 2.2 39 85
Chromium 38.0 1200 3000
Copper 376 1500 4300
Lead 46.9 300 840
Mercury 0.93 17 57
Molybdenum 37.5 18 75
Nickel 34.4 420 420
Selenium <5 36 100
Zinc 1054 2800 7500

*Data for 2013 dewatered biosolids applied to agricultural land; Limits are for Exceptional Quality Biosolids.

Reference: MUextension document WQ-425

Table 2: Nitrogen and Phosphorus Content of Biosolids
Nutrient ** Average %
Nitrate 0.01
Total Kjeldahl Nitrogen 7.00
Ammonia 1.20
Total Phosphorus 3.5

**Data for 2013 dewatered biosolids applied to agricultural land

Nitrogen is essential for plant growth. However, excess nitrogen not utilized by plants can leach into groundwater. Nitrogen exists in different forms in the soil. Ammonia is the form most readily available for uptake by plants. In Table 2, the percentages for nitrate and nitrite, TKN (Total Kjeldahl Nitrogen), and Ammonia are used for compliance with the MO DNR regulations which require calculation of crop nitrogen needs and availability of nitrogen in biosolids applied to land. Phosphorus is also essential for plant growth, but in excess can be detrimental to the health of lakes and rivers. See the Phosphorus page for more details.

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