Comprehensive Guide to Sewage, Refuse Disposal, and Disposal of the Dead

DEFINITIONS AND CLASSIFICATIONS IN SEWAGE MANAGEMENT

  • Sewage: Defined as wastewater from a community containing both solid and liquid excreta. It is derived from residential houses, street and yard washings, factories, and industrial plants.
  • Sullage: Wastewater that specifically does not contain human excreta. Examples include wastewater produced in kitchens and bathrooms.
  • Sewage Management: The collection, treatment, and sanitary disposal of liquid and water-carried wastes originating from households and industry.
  • Sewers: The specific pipes through which sewage flows.
  • Sewerage: The entire network of pipes (sewers) designed for the flow and transport of sewage.
  • Classification of Sewage:
    • Domestic: Comprising human excreta and sullage.
    • Industrial or Trade: Waste generated by industrial processes.
    • Runoff: This includes storm water or flood water.

EXCRETA DISPOSAL AND HEALTH IMPLICATIONS

  • Health Hazards of Improper Disposal:
    • Soil pollution.
    • Water pollution.
    • Contamination of foods.
    • Propagation of flies.
  • Disease Transmission Path: Diseases are carried from faeces through several vectors—Water, Fingers, Flies, and Soil—which then contaminate Food, eventually reaching a New Host.
  • Sanitation Barrier: A sanitation barrier is implemented to block the transmission from faeces to vectors (water, fingers, flies, soil), thereby ensuring that food and potential hosts remain protected.

STANDARDS FOR A SANITARY LATRINE

  • Environmental Protection: It must not pollute the soil surface, surface water, or groundwater.
  • Vector Control: It must not allow flies or other animals to access the sewage.
  • Safety and Maintenance: There must be no handling of fresh sewage.
  • Aesthetics: It should not be smelly or unsightly.
  • Social Factors: It must be simple, affordable, and culturally acceptable to the community for which it is built.

METHODS OF EXCRETA DISPOSAL IN UNSEWERED AREAS

  • Service Type (Conservancy):
    • Bucket Latrine: Involves a human agency removing "night soil" in a bucket. Disposal occurs via burying or composting. This method, along with open defecation, is strongly discouraged.
  • Non-Service Type:
    • Pit Latrine: Consists of a pit, a floor (ideally a reinforced concrete slab for safety), and a superstructure (made of mud, bamboo, thatch, bricks, or tin). The pit must be at least 2 m2\,m deep. It should be sited at least 6 m6\,m from houses and 30 m30\,m away (and downhill) from any water source.
    • Ventilated Improved Pit (VIP) Latrine: A modification designed to eliminate odour and flies using a ventilation pipe equipped with a fly screen. While effective, it is more expensive and difficult to construct than a simple pit latrine.
    • Borehole Latrine: Suitable for rapid construction or situations where a large workforce is unavailable. It typically has a diameter of 400 mm400\,mm and a depth of 5−10 m5 - 10\,m. Constraints include a short lifespan, risk of groundwater pollution, and potential for blockages.
    • Water Seal Latrine (Pour-Flush): Uses a latrine pan with a shallow U-bend (water seal) to prevent smells. Requires a few litres of water to flush excreta into a pit or septic tank. It is ideal where water is used for anal cleansing but can be blocked by solid cleansing materials.
    • Trench Latrine: Shallow trenches where excavated soil is used to cover excreta immediately after use. Used for temporary sites like refugee or work camps. It offers limited privacy and risks fly breeding if not covered properly.
    • Composting: Excreta is mixed with organic waste (ash, sawdust, etc.) in a corrosion-resistant container. This produces humus for organic fertilizer but can produce odours and attract flies.
    • Chemical Toilet: A portable, non-sewered unit often used in caravans, boats, and aircraft. Waste is treated with chemicals like formaldehyde in a tank to aid digestion and reduce odour. It is expensive and requires regular servicing.
    • Septic Tank: An anaerobic digestion system used where water is available. Solids settle and are digested in a tank while clear effluent flows to a soakaway pit for aerobic oxidation in subsoil. Sludge removal (desludging) is required every 1−5 years1 - 5\,years.
    • Aqua Privy: A concrete water-tight tank with an inlet drop pipe that dips into the water, maintaining a constant water level. Effluent is directed to a soakaway pit.

SEWERAGE SYSTEMS AND SANITATION CATEGORIES

  • Sewerage System: The preferred method for high-density cities with reliable water. It involves a network of house sewers, street/trunk sewers, and appurtenances (e.g., manholes) that transport waste to a treatment plant for pathogen reduction.
  • WHO/UNICEF JMP Categorizations (2015):
    • Improved Sanitation: Separates human excreta from human contact. Includes flush/pour flush to piped sewers, septic tanks, or pit latrines; VIP latrines; pit latrines with slabs; and composting toilets.
    • Unimproved Sanitation: Does not separate excreta. Includes flush to elsewhere, pit latrines without slabs, bucket latrines, hanging toilets, shared facilities, and open defecation.

SOLID WASTE MANAGEMENT

  • Refuse/Solid Waste: Non-hazardous, unwanted materials from homes, offices, and farms including household refuse, street sweepings, and demolition debris.
  • Types of Refuse:
    • Garbage: Organic or wet waste from food and plants. Very good for manure; cannot be recycled.
    • Rubbish (Trash): Dry solid waste like paper, plastic, glass, and metal. Can be reused or recycled.
  • Waste Management Hierarchy (Desirability Order):
    1. Prevention
    2. Reduction
    3. Reuse
    4. Recycling
    5. Recovery
    6. Treatment
    7. Final Disposal
  • Management Processes:
    • Segregation at Source: Waste should be separated into biodegradable, recyclable, hazardous, and electronic waste before collection.
    • Storage: Containers must be durable, leak-proof, fitted with lids, and protected from animals.
    • Collection: Methods include door-to-door, kerbside, block collection (timed stops), or community bins.
    • Refuse Transfer: Moving waste from primary collection vehicles to larger, enclosed transport vehicles.

WASTE TREATMENT AND DISPOSAL METHODS

  • Composting: Aerobic decomposition of biodegradable waste by microorganisms to produce nutrient-rich manure.
  • Bio-gasification: Anaerobic decomposition producing biogas (methane and carbon dioxide) for energy and digestate for soil conditioning.
  • Incineration: High-temperature combustion (1200−1500∘C1200 - 1500^{\circ}C) to reduce volume and destroy pathogens. It is not suitable for aerosol cans, halogenated plastics (PVC), or lead-lined materials. It produces ash and potentially toxic emissions (dioxins/furans).
  • Sanitary Landfill (Controlled Tipping): Engineered facility with a protective base lining to prevent groundwater contamination. Waste is compacted and covered with soil daily. Non-porous soil is preferred.
  • Open Dumping: Uncontrolled and unacceptable. It causes fires, odours, drainage blockages, and breeds disease vectors.
  • Burial: Suitable for small quantities in camps, though it risks groundwater contamination.

DISPOSAL OF THE DEAD

  • Burial: Placement of the body in a grave at least 6 ft6\,ft deep. Must be on elevated, well-drained land away from water sources. It is culturally widely accepted but requires significant land.
  • Cremation: High-temperature combustion in a cremator to reduce the body to bone fragments, which are processed into ashes. It saves land and facilitates the transport of remains but requires specialized facilities and fuel.
  • Entombment: Placing the body in an above-ground or partially above-ground chamber, mausoleum, or crypt. It is useful where excavation is difficult but is expensive and requires structural maintenance to prevent leaks or odours.