Smelly+Sewage

= = =Sewage Line or Septic Systems?=

There are two ways in which Basgo could control human waste. Both are efficient, and could be used in this environment.

In a **Sewage Line**, residents pay according to how many gallons of water are used. A Sewage Treatment Plant has three steps in it. The first is Primary Treatment, where metal screens or vertical bars with a mechanical arm are used to remove solids like branches, rags, and paper. Grit chambers are used to help inorganic matter like sand or gravel sink to the bottom, so it doesn't damage the pumps. The grit and solids are sent to a clean landfill. The sedimentation is then used to separate the solid waste from the wastewater, based on the difference in gravity between the solids and the rest of the liquids. In the “Primary Sedimentation” tank, the sewage is there for one or two hours, which makes 50-70% of the solids go to the bottom. This stage lowers the biochemical oxygen demand (BOD) by 25-40%. It also reduces the fecal coli form (poop) by 45-55%. The sludge at the bottom is then sent to an anaerobic digester. This is a closed vessel where the solids are broken down into carbon dioxide and methane by microorganisms (the methane can be used as an energy source).

The second step is Secondary Treatment. Flow from the sedimentary tank and sludge from the place where its cleaned are sent to a bioreactor. This is where the microorganisms break down the organics. This step is also called the “activated sludge process.” Sludge particles called “flocs” are generated. These are made of millions of growing bacteria bound by slime. The clear liquid is brought to the clarifier, and any sludge generated is recycled to the reactor. Activated sludge is able to oxidize organics within 4-8 hours. This step reduced BOD and suspended solids by 85-90%. It also removes 90-99% of the fecal coli forms.

The Last step in the Sewage Line is Tertiary Treatment, and it is really important because it gets rid of the pathogens (pathogens are microorganisms that cause deceases in humans and animals). The type of this treatment that you want to use is based on how pure the city wants the effluent (wastewater). Consider the size of the receiving body of water, and however much use of that water is needed. Chlorination is the most commonly used type of Tertiary Treatment, and gets rid of pathogens, reduces the BOD, odor, and water color. Although this is a good product, it doesn't get rid of viruses, and it can poison the plants and animals. Ultraviolet Radiation can be used, too. It isn't as bad for the environment, but it is more expensive. I recommend using UV Radiation, but because of the budget, we might want to use the Chlorination.

The other choice is to use **Septic Systems**. There's many different kinds of Septic Systems, but they are all similar. Each has three parts, the septic tank, the drain field, and the soil beneath the drain field. A septic tank is about 9 feet long and 5 feet high. It's made of concrete, and it’s buried underground beside the house. The size of the septic tank is determined by the amount of bedrooms in a house. The house is connected to the tank so it can get rid of the waste, and the tank has pipes that go into the drain field. Usually a drain field has 2-5 trenches in the subsoil. They are usually 3 feet wide, 2 or 3 feet deep, and about 9 feet apart from each other. A 1 foot thick layer of gravel is put in them. Over the drain field it must be landscaped, so the water doesn't build up on top. The soil gets rid of germs and chemicals from the wastewater before it reaches water. The Septic Tank is set up so that only the wastewater flows out. On the top there's a layer of greases and fats. On the bottom lies the solids. There's a baffle, which is like a wall coming from the bottom and top with space in the middle. It keeps the solids and the greases in the tank, so that the only thing going into the drain field is the water.

Why do we need to focus so much on this issue? Because we need to make a choice that will keep our estuary clean and safe. There are many things to consider, such as that the Septic Systems could be too far down or high up, so that the wastewater enters the groundwater and estuaries before its clean. The Sewage Line may not work properly, and it may not treat the water enough. Make the decision carefully so that our society is a safe environment.

[|www.simondawson.com/bugch2.htm] [|www.epa.gov/ORD/NRMRL/pubs/625r92013/625R92013chap7.pdf] [|www.soil.ncsu.edu/publications/Soilfacts/AG-439-13/]