Optimization studies on the production of struvite from human urine – waste into value

Abstract

a b s t r a c tRecovery of nutrients from wastewater streams has twin advantages of preventing eutrophication and providing value for the treatment process. Phosphate in significant quantities is available in sewage, with human urine accounting for a major portion. In this context, studies were conducted for the maximum recovery of phosphate as 'Struvite'. The significant variables that affect the struvite recovery from human urine were identified by Plackett Burman design and further optimized using a four factor central composite design. The optimal conditions for phosphate recovery were determined: pH 9.5, Mg to P ratio 1.5, precipitation time 40 min and ammonium concentration 2,000 mg L -1 . The maximum phosphate recovery obtained at optimal condition from synthetic urine sample was significantly higher than the real urine samples. The fertilizing ability of struvite so produced was assessed in comparison with normally used fertilizer 'Di-Ammonium Phosphate (DAP)' under identical conditions using Ixora coccinea L, a popular plant with medicinal values. The growth parameters of Ixora coccinea L were found to be significant for Struvite but could not match the performance of DAP. The twin advantages of lower cost of production particularly with the increasing demand for phosphorus and the utilization of environmentally benign waste product makes study relevant and attractive.

Predictive Capability of Phosphate Recovery from Wastewater Using a Rough Set Machine Learning Model

“…The most suitable wastewater sources for higher phosphate recovery were anaerobic digestate, hydrothermal carbonization liquor of chemically produced dairy sludge, carmine dye industry, synthetic urine, digested sludge centrate, and fertilizer wastewater . However, wastewater sources that come under class 2 and 3 (human urine, poultry wastewater, and swine wastewater) are the most common and available in abundance. , It is also noteworthy that a lot of articles have used synthetic wastewater, which is very chemical- and cost-intensive to prepare. , Utilization of real wastewater can provide a better overview of the outcomes and the difficulties associated with scaling up resource recovery units.…”

“…have recorded this range of parameters for higher recovery of phosphate. , In the case of synthetic urine, the N concentration ranging between 900 and 2000 mg/L with the Mg/N ratio between 1 and 2 shall also result in higher P_recovery as of class 1. Similar results were observed by Sathiasivan et al and Rodrigues et al This rule provides one of the possible conditions for achieving higher P_recovery > 1350 mg/L with the support of 3 parameters rather than focusing on all the 12 input parameters. It is noteworthy that except for N concentration, the remaining two parameters were already earmarked as cores as per the RSML algorithm.…”

Performance evaluation of a microbial fuel cell for resource recovery as struvite and bioelectricity generation from slaughterhouse wastewater

“…The proof of N and P recovery as struvite by chemical precipitation has been well established in batch-and continuous-flow reactors. 26,27 All these conventional methods for struvite precipitation typically require pH adjustment by amending chemicals, rendering them more cost intensive. 28,29 An alternative, namely the bio-electrochemical system, is desirable and uses electrodes where a redox reaction takes place.…”

“…The prevention of ammonia volatilization requires a pH as low as possible whereas precipitation of struvite requires a pH between 7 and 11 for optimal performance. The proof of N and P recovery as struvite by chemical precipitation has been well established in batch‐ and continuous‐flow reactors 26,27 . All these conventional methods for struvite precipitation typically require pH adjustment by amending chemicals, rendering them more cost intensive 28,29 …”