Department of Chemical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia E-mail:
Indah Water Konsortium Sdn Bhd, No. 44, Jalan Dungun, Damansara Heights, 50490 Kuala Lumpur, Malaysia.
Water Sci Technol. 2020 Jan;81(1):71-80. doi: 10.2166/wst.2020.077.
Many developing countries, mostly situated in the tropical region, have incorporated a biological nitrogen removal process into their wastewater treatment plants (WWTPs). Existing wastewater characteristic data suggested that the soluble chemical oxygen demand (COD) in tropical wastewater is not sufficient for denitrification. Warm wastewater temperature (30 °C) in the tropical region may accelerate the hydrolysis of particulate settleable solids (PSS) to provide slowly-biodegradable COD (sbCOD) for denitrification. This study aimed to characterize the different fractions of COD in several sources of low COD-to-nitrogen (COD/N) tropical wastewater. We characterized the wastewater samples from six WWTPs in Malaysia for 22 months. We determined the fractions of COD in the wastewater by nitrate uptake rate experiments. The PSS hydrolysis kinetic coefficients were determined at tropical temperature using an oxygen uptake rate experiment. The wastewater samples were low in readily-biodegradable COD (rbCOD), which made up 3-40% of total COD (TCOD). Most of the biodegradable organics were in the form of sbCOD (15-60% of TCOD), which was sufficient for complete denitrification. The PSS hydrolysis rate was two times higher than that at 20 °C. The high PSS hydrolysis rate may provide sufficient sbCOD to achieve effective biological nitrogen removal at WWTPs in the tropical region.
许多发展中国家，主要位于热带地区，已经在其污水处理厂（WWTP）中纳入了生物脱氮工艺。现有的废水特性数据表明，热带废水中的可溶解性化学需氧量（COD）不足以进行反硝化。热带地区温暖的废水温度（30°C）可能会加速颗粒可沉降固体（PSS）的水解，为反硝化提供慢速可生物降解 COD（sbCOD）。本研究旨在对几种低 COD 与氮比（COD/N）热带废水来源中的 COD 进行不同组分的分析。我们对马来西亚的六个 WWTP 进行了 22 个月的废水采样，并通过硝酸盐吸收速率实验来确定废水中 COD 的各个组分。我们使用耗氧速率实验在热带温度下确定了 PSS 水解动力学系数。废水样本中的易生物降解 COD（rbCOD）含量较低，仅占总 COD（TCOD）的 3-40%。大部分可生物降解有机物以 sbCOD 的形式存在（占 TCOD 的 15-60%），足以进行完全反硝化。PSS 水解速率比 20°C 时高两倍。高 PSS 水解速率可能为热带地区的 WWTP 提供足够的 sbCOD，从而实现有效的生物脱氮。
