By removing nutrients from where they shouldn’t be – in our waterways – and upcycling them into an elegant, sustainable, environmentally responsible fertilizer, Ostara offers a closed-loop, comprehensive nutrient management solution. It helps municipalities meet nutrient discharge limits while providing growers with a tool to lower their phosphorus footprint as they produce the food needed to feed a growing population.
Ostara’s Pearl® Process resolves struvite issues and provides a comprehensive approach to nutrient management. The technology is based on controlled chemical precipitation in a fluidized bed reactor that recovers struvite in the form of highly pure crystalline pellets or “prills.” Nutrient-rich feed streams are mixed with magnesium chloride and, if necessary, sodium hydroxide and then fed into the Pearl reactor where minute particles or struvite “seeds” begin to form. Like a pearl, these seeds grow in diameter until they reach the desired size – 0.9 mm to 3.0 mm – which is precisely controlled by varying key parameters.
In a municipal wastewater treatment plant, up to 85 percent of the phosphorus and 40 percent of the ammonia load is removed from sludge dewatering liquid using this process, and the resulting product is marketed as a commercial fertilizer called Crystal Green®.
WASSTRIP (Waste Activated Sludge Stripping to Remove Internal Phosphorus) turbo-charges nutrient removal and recovery. The process releases phosphorus upstream of the anaerobic digester and sends it directly to the Pearl reactor for recovery.
WASSTRIP increases the overall volume of phosphorus recovered, and importantly, provides critical benefits to plant operations. It reduces overall struvite formation in the digester by up to 90 percent. Struvite is a cement-like substance created from nutrients in the treatment stream that scales upon the equipment causing severe operational issues and costing hundreds of thousands of dollars every year on chemicals to treat. By sending phosphorus directly to the Pearl process and bypassing the digester, WASSTRIP all but eradicates digester struvite. WASSTRIP also reduces biosolids production by up to 25 percent and lowers the phosphorus to nitrogen ratio to create balanced biosolids that are more suitable for land application. In addition, it improves dewaterability, producing 4 percent drier biosolids cake, which, when combined with lower overall volumes, cuts down considerably on handling and disposal costs.