Early detection of struvite formation in wastewater treatment plants

Wastewater treatment plants operating anaerobic digestion of their sludge often have to encounter phosphate-based formations that clog piping, valves and pumps that reduce the efficiency of the treatment plant. In addition to treatment process problems, these formations require significant costs for their removal or to have the clogged piping replaced. Among the many possible phosphate-based precipitates, struvite is the most common. In most instances, the formation and build-up of struvite within the treatment stream goes unnoticed until a critical stage is reached where the only option is replacement of the clogged pipes and valves. However, the early detection of struvite formation through regular monitoring of the parameters that influence struvite build-up can reduce the problems. This paper presents procedures and results obtained to detect struvite formation potential in a secondary wastewater treatment plant in Canada. Based on supersaturation values, it was found that there was a high probability of struvite formation around the sampling points. High nutrient looping for both nitrogen (20%) and phosphorus (48%) were calculated at the treatment plant.