Nutrient recovery from sewage sludge and other organic solid wastes in the form struvite has become the focus of many research studies because of limited phosphorus (P) rock reserves, which are mainly exploited for the production of fertilizers, in the world. There are many additional benefits of recovering nutrients during the anaerobic digestion of the organics by fixing N and P as well.
There are three major tasks forming the main structure of the proposed research plan which can be summarized as follows;
Investigation of struvite precipitation in anaerobic bench scale reactors operating for the digestion of poultry manure and wastewater treatment plant sludge mixtures in different ratios, determination of changes in the performance of coupled ADP and SPT system in relation to different operational parameters, and characterisation of the liquid and solid phase of digestion residues.
Investigation of struvite precipitation in synthetically prepared digestion liquor simulating the aforementioned waste composition as well as full scale anaerobic digesters effluents. Transferring the results to a chemical equilibrium model to understand the mechanisms of reaction(s) in struvite precipitation technique in post ADP samples, and
Investigation of separate struvite precipitation in anaerobically digested residues as well as in a pilot-scale anaerobic digester operating for the mixture of poultry manure with wastewater treatment sludge and the effects of operating parameters on the struvite formation. Comparing the efficiency of separate struvite precipitation of anaerobic digester effluent and coupled (combined) ADP and SPT. In addition, the changes, if any, in the characteristics of the mixed anaerobic culture during the coupled ADP and SPT system will be determined by molecular techniques (such as FAME, PCR, microarrays, etc.). Therefore, the operating conditions leading to the anaerobic cultures achieving the maximum nutrient removal will be determined. Finally, the land applicability of the anaerobic sludge residue enriched by N and P as fertilizer will be investigated.