Liquid Waste (Sewage/Wastewater) Treatment

Wastewater (liquid waste) from flushing the toilet, bathing, washing sinks and general cleaning goes down the drain and into a pipe, which joins a larger sewer pipe under the road. The larger pipe also joins a major pipe that leads to the treatment center.

STAGE ONE: SCREENINGScreening is first stage of the wastewater treatment process. Screening removes large objects like, diapers, nappies, sanitary items, cotton buds, face wipes and even broken bottles, bottle tops, plastics and rags that may block or damage equipment.Special equipment is also used to remove grit that gets washed into the sewer.

STAGE TWO: PRIMARY TREATMENTThis involve the separation of organic solid matter (or human waste) from the wastewater. This is done by putting the wastewater into large settlement tanks for the solids to sink to the bottom of the tank. The settled solids are called sludge. At the bottom of these circular tanks, large scrappers continuously scrape the floor of the tank and push the sludge towards the center where it is pumped away for further treatment. The rest of the water is then moved to the Secondary treatment.

STAGE THREE: SECONDARY TREATMENTThe water, at this stage is put into large rectangular tanks. These are called aeration lanes. Air is pumped into the water to encourage bacteria to breakdown the tiny bits of sludge that escaped the sludge scrapping process.

STAGE FOUR: FINAL TREATMENTNext the almost treated wastewater is passed through a settlement tank. Here, more sludge is formed at the bottom of the tank from the settling of the bacterial action. Again, the sludge is scrapped and collected for treatment. The water at this stage is almost free from harmless substances and chemicals. The water is allowed to flow over a wall where it is filtered through a bed of sand to remove any additional particles.

The filtered water is then released into the river.Important facts of water pollution.

40% of Americas rivers and 46% of Americas lakes are too polluted for fishing, swimming, or aquatic life.1.2 trillion gallons of untreated sewage, storm water, and industrial waste are discharged into US waters annually. Source: Combined Sewer Overflow (CSO), http://www.epa.gov/nrmrl/wswrd/wq/stormwater/cso.pdf

Polluted drinking waters are a problem for about half of the worlds population. Each year there are about 250 million cases of water-based diseases, resulting in roughly 5 to 10 million deaths.Source: Top Facts about Pollution., http://theexpeditionproject.com/info/top-enviro-stuff/522-top-facts-about-pollutionIn 2010, there was a huge oil spill in America by BP. Of the 400 miles of Louisiana coast, approximately 125 miles have been polluted by the oil spill. Over 1,000 animals (birds, turtles, mammals) have been reported dead, including many already on the endangered species list. Of the animals affected by the spill that are still alive only about 6% have been reported cleaned, but many biologists and other scientists predict they will die too. In November 2012, BP agreed a settlement with the US government worth $4.5bn, including a $1.26bn criminal fine.Source: River Pollution., http://prezi.com/q1rbkwvv6xqi/river-pollution/

In April 2010, The Transocean Oil Rig exploded, killing 11 workers. The disaster also damaged the Gulf of Mexico coast causing one of the biggest environmental disasters in US history. In January 2013, the company paid $400m (248m) in criminal penalties and a $1bn civil fine after pleading guilty to violating the Clean Water Act.Source: http://www.bbc.co.uk/news/science-environment-13123036In developing countries, 70% of industrial wastes are dumped untreated into waters where they pollute the usable water supply.Source: WWAPHow the world uses freshwater: about 70 percent for irrigation about 22 percent for industry about 8 percent for domestic useSource: World Water Assessment Programme (WWAP)27% of the urban population in the developing world do not have piped water in their homes.Source: UNESCOA lack of safe water and sanitation in cities leads to cholera,malariaand diarrhoea.Source: WHOInMarch 2011, a very powerful earthquake in the sea (tsunami) hit the Japan coast. The sea level rose and water came into the land, damaging 4 of the 6 reactors in the Fukushima Daiichi Nuclear Power Plant.World Health Organisation (WHO) experts confirm that there is slight increased risk of some cancer types for some people who were exposed to the radiation. These included people living in that area and some workers at the plant. Below is a peice of the information given on BBC website:"The biggest lifetime risks were seen in those exposed as infants, compared with children or adults.For girls exposed to radiation from the accident as infants, the report found a 4% increase above the lifetime expected risk of solid tumours and a 6% increase above that expected for breast cancer.Boys exposed as infants are expected to have a 7% increased risk of leukaemia above that expected in the normal population.The biggest risk was seen in thyroid cancer, which for infant girls could be up to 70% higher than expected over their lifetime."