Waste water

• Wastewater - also known as sewage means used water.
• Domestic Wastewater - wastewater from residences, apartments, motels, and other similar types of buildings.
• Industrial wastewater comes from factories or other manufacturing facilities that produce large amounts of liquid effluent.
• There are two type of domestic wastewater.

  • gray water
  • black water
• Black water - wastewater that contains the fecal matter and urines. It is produced in water closets urinals, and bidets.
• Gray water - wastewater that typically contains the residues of washing process.
• Commercial wastewater - is nontoxic, nonhazardous wastewater from commercial and institutional food service operations and beauty salons.
• OSST or On-Site sewage treatment
• On-Site Sewage treatment - traditionally called septic systems, usually consist of the building sewer.
• Septic tank - watertight, covered container designed to settle out and hold solid wastes and partially treat wastewater with beneficial bacteria.
• Aerobic tank - are substitute for septic tanks.
• aerobic tank consist of trash tank, an aeration chamber and, settling chamber.
• Premanufactured Aerobic tanks - use wastewater treatment processes similar to municipal wastewater treatment processes.
• Aerobic tanks work more effectively than septic tanks and thus can be smaller in size.
• Pump tank - watertight container used to temporarily store clarified effluent before it flows into a drainage field.
• Sand filter - is a lined, impermeable container containing a bed of granular material that provides additional treatment of effluent as it flows from the primary treatment tank to the drainage field.
• Trash/Grease Tank - trash tank is occasionally used in conjunction with an aerobic tank.
• Grease tanks - are used with septic and aerobic tanks, usually in commercial applications.
• cesspool - is a covered underground container that receives untreated sewage directly from a building and discharges it into soil
• Septic tank - is a receptacle or vault used to collect organic waste discharged from the house sewer. The main function of a septic tank is to liquefy and precipitate solid waste purifying odorous materials.
• Sewage that was discharged into the tank is retained. And during its retention period, about 60% to 70% of the suspended solid of the sewage is removed largely by sedimentation to form a semi-liquid substance called sludge.
• Decomposition of organic matter from human waste is a bacteriological process caused by:

  1. Aerobic bacteria called aerobes

  2. Anaerobic bacteria called anaerobes

  3. Facultative bacteria
• Digestion - both the scum and the sludge are processed by anaerobic bacteria and transforming them into liquid and gases.
• They thrive naturally in sewage, and will function when conditions are favorable in terms of:

  1. Food supply
  2. Temperature
  3. Moisture
• Sludge - is a thick, dark brown material composed mainly of decomposed organic matter with some sand, grit, and other solids. It settles at the bottom of the septic tank.
• human waste - also known as excreta
• Decomposition caused by anaerobic bacteria which is sometimes referred to as putrefaction, is accompanied by bad odors.
• A sewage that turns dark and smell unpleasantly due to anaerobic decomposition is called Septic.
• GASSES THAT ARE PRODUCED INSIDE THE SEPTIC TANK

  • Methane gas (CH4)
  • Carbon Dioxide (CO2)
  • Carbon Monoxide (CO)
  • Hydrogen (H2)
  • Hydrogen Sulfide (H2S)
  • Sulfur Dioxide (HO2)
• CONSTRUCTION OF THE SEPTIC TANK Septic Tank is constructed from either of the following materials:

  1. Reinforced concrete
  2. Plastered concrete hollow blocks.
  3. Prefabricated asbestos
  4. Thin metal and plastic
• TECHNICAL DATA DETERMINING VOLUME OF SEPTIC TANK

  Minimum width 90 cm

  Minimum length 150 cm

  Minimum depth 120 cm
• The septic tank must be located at least 3 meters away from any well or spring.
• Inside the septic tank, solids settle to the bottom forming sludge while fats, oils, grease float on top forming scum.