32 - Reclamation of nutrients from mixed wastewater through struvite crystallization techniques

Abstract

The method of struvite crystallization provides a valuable product named “struvite”—a gradual reacting nutrient. In most developing countries, the treatment of wastewater and management of the same were not happening properly. Mostly, the partial treated domestic wastewater was discharged into water bodies. It leads to eutrophication and contamination of water bodies as domestic wastewater contains excess nutrients. It is a difficult task to remove the nutrients fully and also leads to crystalline deposits in wastewater treatment plants. In this present study, an attempt has been made to separate the nutrients through struvite crystallization technique. The source of wastewater was collected from an educational institution’s sewage treatment plant (STP). The wastewater was produced from laboratories, hospitals, student hostels, and canteens. The nature of wastewater was mixed-type wastewater since the mixture was like organic industrial wastewater and domestic wastewater from a STP. The nutrients were recovered through chemical precipitation by using mixed suspension mixed product removal batch reactor. The efficiency of the process in reducing biochemical oxygen demand and chemical oxygen demand was 77% and 80%, respectively, and the recovery efficiency for phosphate and ammonia was 95% and 91%. The amount and the purity of struvite were observed as 3.25 ± 0.15gm/L and 75%–85%, respectively. This technique also helps to produce value-added product; it will indirectly help in reducing the load of the treatment process of the STP. Because in most of the treatment process, nutrient reduction is an important task in wastewater treatment. If this technique is coupled with any other conventional technique, then the outcome of the process will be more effective.