Economic Model Predictive Control for optimal struvite recovery.

Resource recovery from municipal wastewater has been a prime focus for a decade. Although several recovery processes already exist in the market today, the high cost of material, inherent disturbance in the influent quality, lack of real time monitoring of critical parameters, and lack of a robust automation system may result in suboptimal performance. This work attempts to construct a model based predictive control for optimal operation of a struvite recovery unit in a full scale WRRF. A multi-parameter based predictive control has been developed by implementing an Economic Model Predictive Controller (EMPC) for optimal dosing of magnesium hydroxide in a struvite recovery unit. The EMPC used customized objective function for real-time optimization of performance and economical parameters of the crystallization unit. The effectiveness of the proposed EMPC controller is verified through tests conducted on the Benchmark Simulation Model No. 2 (BSM2d.). The results obtained from the simulator-based evaluation of EMPC demonstrate a significant improvement in resource recovery at reduced operational costs. The economic advantages of implementing an EMPC compared to proportional and constant magnesium dosage has also been enumerated.

Struvite-Driven Integration for Enhanced Nutrient Recovery from Chicken Manure Digestate.

This study investigated the synergistic integration of clean technologies, specifically anaerobic digestion (AD) and struvite precipitation, to enhance nutrient recovery from chicken manure (CM). The batch experiments were conducted using (i) anaerobically digested CM digestate, referred to as raw sample (RS), (ii) filtered digestate sample (FS), and (iii) a synthetically prepared control sample (CS). The research findings demonstrated that the initial ammonia concentration variations did not significantly impact the struvite precipitation yield in the RS and FS, showcasing the materials inertness process's robustness to changing ammonia concentrations. Notably, the study revealed that the highest nitrogen (N) recovery, associated with 86% and 88% ammonia removal in the CS and FS, was achieved at pH 11, underscoring the efficiency of nutrient recovery. The RS achieved the highest nitrogen recovery efficiency at pH 10, at 86.3%. In addition, the research highlighted the positive impact of reducing heavy metal levels (Zn, Cu, Pb, Ni, Cd, Cr and Fe) and improving the composition of the microbial community in the digestate. These findings offer valuable insights into sustainable manure and nutrient management practices, emphasizing the potential benefits for the agricultural sector and the broader circular economy. Future research directions include economic viability assessments, regulatory compliance evaluations, and knowledge dissemination to promote the widespread adoption of these clean technologies on a larger scale. The study marks a significant step toward addressing the environmental concerns associated with poultry farming and underscores the potential of integrating clean technologies for a more sustainable agricultural future.

Phosphorus recovery from source-diverted blackwater through struvite precipitation.

Phosphorus recovery from wastewater through struvite precipitation is becoming a promising strategy to both mitigate eutrophication risk due to excess phosphorus discharge into water bodies and alleviate the global phosphorus crisis by producing value-added fertilizer. However, the composition and quality of wastewater differ among regions and home to home. Source-diverted blackwater, especially concentrated blackwater collected from vacuum toilet systems, typically has a moderate phosphate-phosphorus (PO4-P) content, high ammonia-nitrogen (NH4-N) content, strong buffering capacity as a result of high alkalinity, and a high pH close to 9. Thus, concentrated blackwater is a good source for phosphorus recovery through struvite precipitation. In this study, we examined the feasibility of recovering phosphorus from concentrated blackwater through struvite precipitation by conducting batch experiments. The characterization of the struvite produced from concentrated blackwater was performed via X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) techniques. The metal contents of the struvite product were analyzed by inductively coupled plasma mass spectrometry (ICP-MS), and its purity was determined. A phosphorus removal efficiency exceeding 90% was achieved as a result of both an appropriate supersaturation ratio of struvite (>4.0) and a high initial pH. The high quality of the produced struvite was demonstrated by a purity of 94.9%, the Mg/P/N mass ratio of 10:12:4.7 based on the EDS analysis, and low heavy-metals contents. This feasibility study provides evidence for the efficacy of phosphorus recovery from concentrated blackwater through struvite precipitation in decentralized wastewater management systems.