Conference on Environmental Science and Technology

Conventional wastewater treatment plants are not integrated biorefineries, resulting in the discharge of phosphorus- and nitrogen-rich effluents. This not only contributes to eutrophication but also leads to the loss of valuable, recoverable resources such as non-renewable phosphorus. Struvite crystallization (SC), a robust nutrient recovery technology, offers a sustainable solution by producing market-ready, waste-derived struvite fertilizers. This critical review provides a comprehensive analysis of SC technologies, focusing exclusively on studies using real wastewaters. Among various wastewater types, SC from liquid digestates of municipal wastewater demonstrates the highest technological readiness level (TRL) 9. Chemical precipitation remains the most applied method due to its simplicity and low cost. However, recent methodological advancements in electrochemical precipitation and membrane crystallization show promising potential. Notably, microbial electrolysis cells enable the formation of high-purity struvite crystals with reduced energy consumption and the added benefit of hydrogen production. Cutting-edge systems such as peroxodisulfate-assisted electrooxidation combined with electrocoagulation, have also emerged as viable alternatives. Operational parameters, pretreatment techniques such as catalytic thermal hydrolysis, and enhancement methods such as zeolite seeding are also scrutinized. For the first time, post-harvest processes like granulation are critically assessed. By bridging research gaps across TRLs, this presentation provides insights to advance scalable SC technologies.