waste water treatments

• where does the water we use at home go

  sewage treatment plants
• what water waste do agricultural systems produce

  nutrient run-off, slurry from farm animals
• why does sewage from domestic or agricultural sources have to be treated

  to remove any organic matter and harmful microbes before it can be put back into freshwater sources
• why does industrial waste water have to undergo additional stages of treatment before being released

  because it contains harmful chemicals
• what is the first step to waste water treatments at sewage plants

  sewage is screened, this is removing any large bits of material like twigs and plastic bags and grit
• what is the second step to waste water treatments at sewage plants

  sedimentstion, water stands in a settlement tank, the heavier solids sink to the bottom to produce sludge while the lighter effluent floats to the top
• what is the third step to waste water treatments at sewage plants

  aerobic digestion, the effluent is treated by air being pumped through the water to encourage aerobic bacteria to break down any organic matter(microbes), then is released into the environment
• what is the fourth step to waste water treatments at sewage plants

  anaerobic digestion, the sludge is transferred into large tanks where organic matter is broken down by bacteria releasing methane gas
• what is the sludges methane gas used for

  fertiliser and natural gas for stoves
• what are the additional stages for waster water containing toxic substances

  adding chemicals (UV radiation) or using membranes