Question

2. An industrial wastewater is discharged into a municipal wastewater sewer. The characteristics of the two wastes are given below. Determine the characteristics of the mixture.

Parameter	Industrial	Municipal
Flow, m3/day	3000	18000
BOD5, mg/L	1500	250
PO43-, mg/L	150	2.3

Answer 1

Here the an Industrial wastewater is discharged into a municipality wastewater sewer.

We have the parameter

Flow for the Industry , where as Municipal flow

That means the Sewer for the municipal is having high flow rate of waste water than Industry.That indiactes that the waste water percentage is very high in Municipal area.

What is BOD?

With the growing importance of effective pollution control, added emphasis has been placed on the Biochemical Oxygen Demand (BOD).

Many municipalities use BOD loads to determine charges and surcharges for industrial users of waste treatment facilities. More importantly, BOD strength is a measure of plant losses during handling and processing of dairy products.

Biochemical oxygen demand is a measure of effluent strength in terms of the amount of dissolved oxygen utilized by microorganisms during the oxidation of organic components in the effluent. BOD is determined by incubating a suitable dilution of effluent in a standard dilution water or specific composition at 68°F. After incubation, the amount of dissolved oxygen consumed is obtained by titration and the results expressed as parts per million of BOD. Complete biological oxidation generally requires about 20 days at 68°F. However, the test has been standardized to be completed in 5 days, hence the term BOD5. If no inhibiting substances are present, the oxidation of milk solids is approximately 68-70% complete in 5 days.

Then the for Industry ( ppm =mg/L) for Industry

Where as for Municipal

Their mixture will be too high. We have to stand with maximum demand of Oxygen.

That means Industry need Higher Oxygen demand for the oxidation of industrial effuluents than Municipal

Phosphate ion Contain:

Inustrial contain Phosphate ion Where as Municipal waste contain Phosphate ion

That means waste of Industry has high Phosphate ion.Removal of phosphate from wastewater by chemical precipitation and advanced biological treatment methods. Among a variety of removing techniques, adsorption is known to be more useful and economical. Fly ash and slag have been used as a potential adsorbent for removal of phosphate, heavy metals and organic pollutants for water pollution control or wastewater treatment.

The mixture Will tend to increase the amount of Phosphate ion in Municipality which need to be removed by above discussed methods.