4. GENERAL TOPICS (a) You are asked to examine the various residues (solids) in a wastewater sample The Total Solids Test resulted in 36,00 mg/L; while the Total Suspended Solids resulted in 28 25 mg L in both cases the volume of the water sample used was 100 mL. What would the expected experimental result be in determining Total Dissolved Solids in mg/L (10 points) (b) During a biological treatment process, the nonspecific water quality parameter COD (Chemical Oxygen Demand) of a domestic wastewater sample is observed to decay over time as follows: Time (hours) 0 2.0 4.0 6.0 8.0 10.0 COD (mg/l) 489 312 185 98 58 29 Determine the reaction order and the decay rate constant "k" with appropriate units. (15 points)