Development of non-conventional biotechnological processes for the valorisation and recovery of wastewater and industrial effluents

The increasing global demand for clean water and sustainable resource management necessitates a paradigm shift in wastewater treatment processes. This thesis investigates innovative biotechnological approaches focusing on A-B process configurations to achieve energy-efficient nitrogen removal while exploring carbon recovery pathways. The membrane aerated biofilm reactor (MABR) technology demonstrated successful partial nitrification-anammox under mainstream conditions. A start-up strategy was developed, and process stability was achieved through intermittent aeration strategy, maintaining bulk fluid DO below 0.2 mg O2/L for effective NOB suppression. A novel partial denitrification-anammox process using moving bed biofilm reactor (MBBR) technology revealed ethanol as a superior carbon source compared to methanol, achieving nitrogen removal efficiency of 80% vs. 60%. The process demonstrated stable performance even at 15°C, while reducing carbon requirements by 80% compared to conventional denitrification. In parallel, a computer vision-based analytical tool (CamCol) was developed for rapid quantification of nitrogen species using colorimetric test strips. The method achieved high accuracy (R² > 0.99) across measurement ranges comparable to standard laboratory methods, demonstrating good agreement with both colorimetric LCK kits and HPIC analysis of real wastewater samples. Investigation of cellulose-rich sludge valorisation revealed promising carbon recovery pathways, achieving VFA yields of 0.11–0.12 gVFA/gVS through acidogenic fermentation of untreated material. The biomethane potential tests demonstrated energy recovery potential (360 mL CH4/gVS for wet CRS). Additionally, enzymatically hydrolysed sugar-rich fraction yielded 21 g/L of VFAs. These findings contribute to the broader goal of transforming wastewater treatment plants from energy-intensive facilities into resource recovery centres. The integration of these innovative approaches demonstrates potential for significant reduction in energy consumption while maintaining or improving treatment efficiency, marking important steps toward sustainable wastewater treatment.