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OER Name: Treatment of Polluted Water

Category: Science and Technology

Target Audience: Level 2 Chemistry Students

Objective: To familiarize the water pollution and its treatment techniques.

Water is an essential substance for living systems as it allows the transport of nutrients and waste products in living Systems. Today, hundreds of millions of people in vast regions of the world do not have access to water to meet their basic needs. Wastewater is used water. It includes substances such as human waste, food scraps, oils, soaps and chemicals. In homes, this includes water from sinks, showers, bathtubs, toilets, washing machines and dishwashers. Businesses and industries also contribute their share of used water that must be cleaned. The major aim of wastewater treatment is to remove as much of the suspended solids as possible before the remaining water, called effluent, is discharged back to the environment. As solid material decays, it uses up oxygen, which is needed by the plants and animals living in the wate Primary treatment removes about 60 percent of suspended solids from wastewater. This treatment also involves aerating (stirring up) the wastewater, to put oxygen back in. Secondary treatment removes more than 90 percent of suspended solids

Treating waste Waste Water Treatment

1.We remove debris and large objects by passing the waste water through specially designed filter screens. 2.Sewage is transferred into a settlement tank where solid matter sinks to form sludge. 3.The liquid sewage flows on to stage three which involves biological treatment. Here, filters of stone containing billions of bacteria and small organisms remove any organic pollutants. 4.Finally, the sewage enters our settlement tanks where any remaining micro-organisms and sludge sink to the bottom. From here, the treated water can be returned to the environment. Most of the sludge produced is then digested and conditioned to create a stable material suitable for recycling to farmland - this is called biosolids recycling. Alternatively a proportion of the sludge may be burnt harmlessly in our sewage sludge incinerators.

Discussion Questions

• Where does the water that enters your home come from? • Why is it important to treat water before sending it to homes? • What do you think the brown sludge is made of? What other things do you think are removed from water to make it safe for drinking? • Water is becoming more contaminated and scarce. What can (or do) you do to conserve water? List 5-10 different ways.