Impurities in Wastewater &

Problems Caused by It

By:Nikhil Sharma

BE/8034/09

What is Waste Water?

Wastewater is any water that has been adversely affected in quality by anthropogenic influence.

It is usually produced from by-products of otherwise purposeful human activities.

Classification:

Waste Water

Industrial Waste Water

Sewage (Domestic Waste Water)

Wastewater quality indicators or how to determine the quality of the waste water?

The BOD5 test:BOD measures the rate of oxygen uptake by micro-organisms in a sample of water at a temperature of 20°C and over an elapsed period of five days in the dark.

Origins:

•Human Waste (Blackwater)•Surface Runoff:• Detergents• Disinfection by-products• Insecticides and herbicides• Petroleum hydrocarbons• Ammonia from food processing waste• Fertilizers containing nutrients(Nitrates and Phosphates)

•Heavy Metal Industries•Thermal Power Plants (Heated Water)•Nuclear Power Plants•Deep Sea Mining•Oil Spills•Heavy Metal Mining

Consequences:

•Ocean Acidification: Oceans are carbon sinks but cannot cope with increase in CO2 .

•Eutrophication•Bio Magnification/Bio Accumulation•Increase in BOD (Biochemical Oxygen Demand)•Marine Debris•Still Water Bodies•Reduction of natural reserve of potable water Fig: Acidification of the

ocean has caused the fringing of coral reefs in the Maldives

Fig: Polluted LagoonFig: Direct discharge of heavy metals to water bodies

Fig: Marine Debris

Problems Arising:

•Toxic waste reaches humans through animals upon consumption.•Great loss of wildlife.•Spread of water borne diseases. (ex. Malaria,Cholera,Jaudice,etc.)•Excessive water treatment required before water is fit for consumption•Pressure on groundwater reserve leading to decrease in water table.•Presence of choliform microorganisms leading to health problems•Consumption of heavy metals (Hg,Pb,As,Cd,Ni) causing birth defects and other disorders (ex. Mercury causes Mina Marta, Lead causes Akai Akai•Oil spills lead to many complications in marine animals and life directly or indirectly dependant on it

Methods of Control:

•Oil spill (coordinated cleanup)

•Domestic sewage treatment plant•Bacterial Treatment

•Industrial waste water treatment plant• Cooling ponds: Through evaporation, convection, and radiation• Dissolved air flotation system• On site water treatment plant for large industries

Fig: Dissolved Air flotation System

The End