Consider Group no$23.$

A food processing industry generates $2000\frac{m^3}{d}$ of wastewater per day. The pollutant concentration of the generated wastewater is given below.

$pH=5\mathrm{.}0$

Group number$)m\frac{g}{L}$

COD$=3500Y($Group number$)m\frac{g}{L}$

$N{H}_4-N=100Y($Group number$)m\frac{g}{L}$

$TN=250Y($Group number$)m\frac{g}{L}$

Group number$)m\frac{g}{L}$

The industry used to discharge the wastewater directly into an adjacent river. Such disposal was associated with massive aquatic pollution of the river. The local environmental regulation authority instructed the food industry to treat wastewater before disposal. You have been appointed as an environmental consultant to propose a treatment plant for that industry.

$($a$)$ Calculate the organic biodegradation ratio of the wastewater and comment on whether the wastewater is biodegradable or not.

$($b$)$ Propose a treatment flow diagram for the industry so the treated effluent meets the local discharge guidelines: $BO{D}_5=20m\frac{g}{L},$COD$=40m\frac{g}{L},N{H}_4-N=10m\frac{g}{L},TN=30m\frac{g}{L},TP=5m\frac{g}{L}.$ Explain the pollutant removal mechanisms of your proposed treatment system and the factors associated with maintaining its smooth operation.

$($c$)$ Due to accidental spillage of stored industrial chemicals into the river, the ecological balance was severely disrupted. Substantial death of fish was observed in the river along with the transformation of the river into a black water body. What engineering measures would you undertake to restore the river's ecological balance and prevent similar infrequent accidental incidents in the future? $[$