Land application of phosphorus-laden sludge: a feasibility analysis

Area of Science:

• Environmental Engineering
• Waste Management
• Soil Science

Background:

• Regina Wastewater Treatment Plant produces phosphorus-laden chemical sludge and dewatered primary sludge.
• Current disposal methods include landfilling and lagooning, which may not be sustainable.
• Investigating alternative, beneficial uses for sludge is crucial for resource recovery.

Purpose of the Study:

• To examine the aerobic digestion of phosphorus-laden sludge.
• To assess the feasibility of land application for a mixture of aerobically digested chemical sludge and anaerobically digested primary sludge.
• To compare the agricultural suitability of the mixed sludge with primary sludge alone.

Main Methods:

• Experimental aerobic digestion of chemical sludge.
• Analysis of heavy metal and nutrient content of digested sludges.
• Feasibility assessment for land application based on regulatory criteria.

Main Results:

• Aerobic digestion effectively stabilizes the chemical sludge.
• The mixed sludge met heavy metal criteria for agricultural use.
• Mixing increased nutrient concentration and decreased heavy metal concentration.
• The mixed sludge offers a longer useful life for agricultural sites.

Conclusions:

• Aerobic digestion is a viable method for stabilizing phosphorus-rich sludge.
• Land application of the mixed digested sludges is a more sustainable and beneficial disposal method.
• This approach enhances resource recovery and reduces environmental impact compared to landfilling and lagooning.