PILOT-SCALE DEEP OXYGENATION FOR HYPOXIA MITIGATION AND WATER QUALITY IMPROVEMENT IN SUNGAI KLANG, MALAYSIA

Urban river systems in tropical regions are increasingly threatened by non-point source pollution, leading to hypoxic conditions and ecological degradation. This study evaluates the effectiveness of a pilot-scale deep oxygenation system for in-situ remediation of water extracted from a polluted section of Sungai Klang, Malaysia. The objectives were twofold: (i) to establish baseline water quality parameters in reference to Malaysia’s Department of Environment (DOE) Standard B, and (ii) to quantify the effects of controlled oxygenation over a five-day treatment period. Baseline characterization included dissolved oxygen (DO), biological oxygen demand (BOD₅), chemical oxygen demand (COD), total suspended solids (TSS), nutrient species (NH₄⁺-N, NO₃⁻-N), and trace metals (e.g., Mn, Fe). The experimental design comprised a two-day monitoring phase without intervention, followed by a five-day oxygenation phase using submerged diffusers. Water samples were collected at fixed intervals to evaluate temporal dynamics. The intervention yielded a 68% increase in DO within 24 hours (p < 0.05), elevating levels from hypoxic (≤2 mg/L) to normoxic (>5 mg/L) conditions. Substantial reductions in organic load were also observed, with BOD₅ and COD decreasing by 42% and 35%, respectively. Declines in TSS, turbidity, and dissolved manganese indicated enhanced oxidative precipitation and microbial activity. Diurnal fluctuations in DO and pH, driven by algal photosynthesis, further highlighted dynamic system responses. These findings represent the first empirical validation of deep oxygenation technology in a Malaysian urban river context, demonstrating its potential to significantly improve water quality while reducing dependence on chemical coagulants and energy-intensive aeration in downstream treatment. The synergy between physicochemical stabilization and microbial metabolism underscores the approach’s relevance for tropical systems, where elevated temperatures exacerbate oxygen depletion. This study provides a foundational framework for scaling oxygenation-based remediation, calling for further investigation into long-term performance and integration with nature-based solutions for sustainable urban water management.