Problem 7-29 The initial ultimate BOD after mixing of the Noir River is 50 mg/L. The DO in the river after the wastewater and river have mixed is at saturation. The river temperature is 10 °C. At 10 °C, the deoxygenation rate constant kd is 0.30 d-¹ and the reaeration rate constant k is 0.30 d-¹. Determine the critical point to and the critical DO.

There is a sewage sludge with volume containing a certain moisture content p, (percent). What will be the volume of this sludge if its moisture content is reduced to p (percent).

An analysis for determination of solids in the return sludge of activated sludge process was done as follows: (1) A crucible was dried to a constant mass of 62.485 g. (2) 75 ml of a well-mixed sample was taken in the crucible. (3) The crucible with the sample was dried to a constant mass of 65.020 g in a drying oven at 104° C. The crucible with the dried sample was placed in a muffle furnace at 600°C for an hour. After cooling, the mass of the crucible with residues was 63:145 g. The concentration of organic fraction of solids present in the return sludge sample is

In a biological wastewater treatment system, which of the following conditions could beconsidered as an anoxic condition: ( )(A) [Dissolved Oxygen] = 3.5 mg/L and [Ammonia-N] = 10 mg/L;(B) [Dissolved Oxygen] = 0.3 mg/L and [Nitrate-N] = 15 mg/L;(C) [Dissolved Oxygen] = 0.05 mg/L and [Nitrate-N] = 0.1 mg/L;(D) [Dissolved Oxygen] < 0.05 mg/L and [Ammonia-N] = 10 mg/L

A secondary treatment using a mixed water activated sludge system, have the flow rate of 10000m^3/day of municipal wastewater. BOD after primary clarification is 150mg/L.It is desired to not reach 5mg/L of soluble BOD in effluent. The kinetic values of the system having X=0.5kg/kg and Kd=0.05d^-1.MLVSS concentration in the secondary treatment is 3000 mg/L, the concentration in return sludge is 10000mg/L. Calculate the volume of solid that must be wasted each day for each of the selected sludge.

Please solve this with explanation of steps

2. At what point in a treatment system is ion exchange normally used?

At the location of a wastewater discharge, a contaminant is well mixed across a river that is 5 mwide and 1 m deep. The flow in the river is 2 m3/s, the contaminant concentration is 200 mg/L, thelongitudinal diffusion coefficient is 3 m2/s, and the decay constant is 50 d−1. (a) What is the maximum contaminant concentration that is expected at a location 2 km downstream of the wastewater discharge?(b) How would this maximum concentration be affected if the waste discharge is limited to operating for only 30 minutes per day.

12.60 The aeration tank for a completely mixed aeration process is being sized for a design waste- water flow of 7500 m³/d. The influent BOD is 130 mg/l with a soluble BOD of 90 mg/l. The design effluent BOD is 20 mg/l with a soluble BOD of 7.0 mg/l. Recommended design para- meters are a sludge age of 10 d and volatile MLSS of 1400 mg/l. Selection of these values takes stants from a bench-scale treatability study are Y into account the anticipated variations in wastewater flows and strengths. The kinetic con- 0.60 mg VSS/mg soluble BOD and k₁ = 0.06 per day. Calculate the volume of the aeration tank, aeration period, food ganism ratio, and excess biomass th

A 14 mgd wastewater treatment plant has a primary clarifier that treats an influent with 800 mg/L of solids and a removal efficiency of 55%. Sludge at the bottom of the tank is pumped at a rate of 0.1 mgd. 1. What is the effluent solids concentration from the clarifier (in mg/L)? What is the solids concentration in the sludge at the bottom of the tank (in mg/L and %)? The primary sludge is further processed in a digester following treatment. What weight of solids (in lbs) need to be handled each week? а. b. с.