1.1. Municipal waste water treatment plant. Consider a municipal water treat- ment plant for a small community (Fig. P1.1). Waste water, 32 000 m³/day, flows through the treatment plant with a mean residence time of 8 hr, air is bubbled through the tanks, and microbes in the tank attack and break down the organic material microbes (organic waste) + 021 * CO,+H,O A typical entering feed has a BOD (biological oxygen demand) of 200 mg O₂/liter, while the effluent has a negligible BOD. Find the rate of reaction, or decrease in BOD in the treatment tanks. Waste water, 32,000 m³/day 200 mg 02 needed/liter Figure P1.1 Waste water treatment plant Clean water, 32,000 m³/day Mean residence time = 8 hr Zero O₂ needed