Organics removal from office wastewater in attached growth biological process of a packaged onsite wastewater treatment system

Advancements in onsite wastewater treatment technology have attracted attention since various types of wastewater can be viably treated and reused at production. In the case of wastewater produced by buildings, including offices (including laboratories and workshops), wastewater is dilute and has particular characteristics warranting an investigation of the performance of onsite systems. This paper investigates the performance of an attached growth biological process in a full-scale onsite wastewater treatment system treating office wastewater. The organics removal efficiency of biochemical oxygen demand (BOD) and chemical oxygen demand (COD) of 93.0% and 93.3%, respectively, were achieved, and nutrient removal efficiency was 72.3 +/- 0.7 and 25.9% +/- 0.9% for total nitrogen (TN) and total phosphorous, respectively. The low nutrient concentrations and the presence of inhibitive chemicals such as phenols, metals, and high ammonia concentrations have caused unfavourable conditions for biomass growth, and caused washout (particularly heterotrophs) and reduced efficiency. Due to these factors, organics removal was as low as 5.2% and 4.8% for BOD and COD, respectively, and nutrient removal was as low as 65.4% and 0.0% for TN and TP, respectively. These performance limitations constitute essential guidance for using similar onsite treatment systems.