Abod test is to be run on a sample of wastewater that has a five-day bod of 230 mg/l. if the initial do of a mix of distilled water and wastewater is 8.0 mg/l, and the test requires a decrease in do of at least 2.0 mg/l with at least 2.0 mg/l of do remaining at the end of the five days, what range of dilution factors (p) would produce acceptable results? in 300 ml bottles, what range of wastewater volumes could be used?

An external consultant recommends that a plant installs a bank of capacitors for power factor correction. this will reduce the peak electrical demand charges by an average of 93 kw every month. the plant current pays $13 per kw in peak demand charges. the capacitor bank will include 223 kw of fixed capacitors, and 183 of variable capacitors. the fixed capacitors cost $59 per kw, and the variable capacitors will cost $65 per kw. the consultant charges 21% of the equipment costs to install the capacitors. because this project will reduce the demand for the electric utility, they are prepared to provide a one-time rebate of $42 per kw of reduced demand. what is the simple payback period for this project (in years)?