Wastewater Treatment and Sanitation Overview

Wastewater Treatment

• Sewage: Wastewater from homes, industries, and hospitals; contains harmful microbes. Untreated sewage pollutes water sources and causes illness.
• Sewers: Underground pipes transporting sewage.
• Sewage Treatment: Removing pollutants from sewage.
• Sewage Treatment Plant (STP): Facility where sewage is treated.
• Manhole: Covered vertical hole above underground sewers for access to pipes for cleaning and repairs. Manholes are placed at junctions of sewers or pipeline changes every 50-60 meters.
• Contaminants: Impurities in wastewater.
• Sludge: Solid waste that settles during treatment. Treated by anaerobic bacteria, producing biogas for energy.

Sanitation and Health

• Poor sanitation leads to diseases: Typhoid, cholera are examples. Contaminated water spreads infections causing health problems.
• Septic Tank: Underground tank for treating household sewage. Solid waste settles and decomposes by bacteria; clarified water exits through an outlet.
• Medicines in drains: Should not be thrown in as they can kill useful microbes needed for decomposition and water purification.
• Untreated human excreta: A health hazard; causes poor sanitation, water and soil pollution, and diseases (cholera, typhoid, dysentery).
• Citizen Role: Keep surroundings clean, manage home sewerage, report leaks, avoid littering, keep water sources clean, cover open drains, and practice good sanitation.

Wastewater Treatment Plant (WWTP) Processes

• Screening: Removes large objects (plastic bags, rags, sticks) using bar screens.
• Grit and Sand Removal: Slows down wastewater to allow grit, sand, and pebbles to settle.
• Primary Sedimentation: Heavy solids settle at the bottom.
• Skimming: Removes floating oil and grease.
• Clarified Water: Free of solid and floating impurities.
• Aerating tank: Compressed air provides oxygen for aerobic bacteria that break down organic matter. Without this, decomposition is slower or ineffective.
• BOD (Biochemical Oxygen Demand): Measures oxygen needed by bacteria to break down organic matter in water. High BOD indicates pollution.

Wastewater Management Issues

• Harmful effects of sewage: Spreads diseases, produces foul odor and pollution, causes waterborne diseases, blocks drains, and attracts insects and mosquitoes.
• Cooking oil/fats: Should not be thrown down drains as they harden and block pipes, reducing drainage efficiency.
• Solid wastes (tea leaves, food remains, cotton): Should not be thrown in drains; they choke drains and block oxygen for beneficial microbes.
• Chemicals (paints, solvents): Should not be disposed of in drains as they kill beneficial microbes important for waste decomposition and water purification.
• Low-cost sewage disposal systems: Septic tanks, chemical toilets, vermicomposting toilets, biogas plants, composting pits offer alternatives to centralized systems.
• Disinfection: Chlorine and ozone.

Definitions

• Sewage: Wastewater carried away in sewers.
• Sewerage: Network of pipes carrying sewage.
• Cleaning water: Removing pollutants from water.
• Dried sludge: Used as manure.

Waste management in the UAE

• Abu Dhabi Sewerage Services Company (ADSSC): Collects and treats wastewater in Abu Dhabi.

Additional Information

• Sources of sewage: Domestic, commercial, industrial, and rainwater.