Monitoring Data

BSTF 2020 Picture
Biosolids generated at the Southwest Clean Water Plant meet the most stringent federal and state regulations for pollutants.

Biosolids Pollutant Levels & Regulated Limits


Metal
2020 SWCWP Biosolids Average mg/kg
Exceptional Quality mg/kg
Ceiling Concentration mg/kg
Arsenic
<5
41.0 75.0
Cadmium
<5 39.0
85.0
Chromium 70.0  1,200 3,000
Copper 253 1,500
4,300
Lead 29.6  300 840
Mercury 0.43 17.0 57
Molybdenum 9.4 18.0 75
Nickel
28.9 420 420
Selenium <10
36.0 100
Zinc 585 2,800 7,500
Note: Exceptional Quality and Ceiling Concentration categories are based on U.S. EPA and Missouri DNR regulation limits.

Nitrogen & Phosphorus Content of Biosolids


Nutrient
Average %
Ammonia
2.03
Nitrate 0.01
Total Kjeldahl Nitrogen
6.10
Total Phosphorus
3.57
Note: Average % data for 2020 dewatered biosolids applied to agriculture land.

Table Explanation


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 the above table, the percentages for nitrate and nitrite, TKN (Total Kjeldahl Nitrogen), and Ammonia are used for compliance with the Missouri 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.