4 - Self-Purification of Natural Waters

• Excreta disposal manages waste to make it safe to release into the environment.

Environmental System

• The environmental system involves the interaction between life-support systems, human activities, and environmental hazards.
• Key components of the system include nutritive and non-nutritive energy sources, the social environment, built environment, and geophysical aspects such as air, land, and water.
• Human activities like work, recreation, residential, and transportation generate residues and wastes that can pose environmental hazards.
• Residues and waste can lead to hazards, including biological, chemical, physical, psychological, and sociological issues.
• Residues and waste improperly managed affects the life-support systems and causes pollution.

Excreta

• Excreta refers to bodily waste, comprising feces and urine, which is a primary source of pathogenic microorganisms.
• Human excretions contain inorganic chemicals like Nitrogen, Phosphorus and Potassium.
• Averages of 3.1-5.6 kg Nitrogen, 0.24-0.4 kg Phosphorus and 0.6-1.0 kg Potassium are excreted, and only small fractions appear in feces.
• Nutrients, pathogens, organic matter and NPK are known components of excreta that can act as pollutants

Soil Pollution Patterns

• In dry soil, pollutants from septic tanks (nutrients and pathogens) travel downwards because septic tanks aren't cemented at the bottom.
• Vertical movement of excreta is limited to 3 meters, horizontal movement to 1 meter.
• Groundwater is less likely to become polluted in mountainous areas since groundwater resides far beneath septic tanks.
• Pollutants move with the direction of groundwater flow at a velocity of 1-3 meters per year.
• Locating a pollution source upstream increases the likelihood of groundwater contamination.

Environmental and Health Impact

• Turbidity, caused by solids in water, harms aquatic life, reduces the depth of water bodies and can lead to flooding.
• Oxygen depletion occurs when organic matter and excreta are discharged into water, which can suffocate aquatic life.
• Eutrophication happens when NPK enriches bodies of water, leading to algal blooms and fish kills.

Diseases

• Water-borne diseases are caused by chemicals or pathogens from contaminated water.
• Examples include Methemoglobinemia, cholera, typhoid and hepatitis A.
• Water-washed diseases are caused from a lack of water and lack of personal hygiene.
• Examples include trachoma, ascariasis and pediculosis.
• Water-based diseases are caused by parasites living in the water such as schistosomiasis.
• Water-related diseases are caused by vectors that breed or bite near water such as Malaria.

Transmission and Classifications

• Transmission of excreted related infection and the classifications depends on these factors (excreted load, characteristics of organism in excreta i.e; latency, infective dose, persistence, multiplication, suceptibility of host)

Environmental Health

• The health impact of sanitation improvements varies across categories.
• The primary focuses on water for hygiene.
• Key elements include solids, organic matter, oxygen depletion, nutrients, pathogens, and inorganic chemicals.

Excreta Disposal Facilities

• Excreta disposal facilities aim to contain and process human wastes to make them safe for environmental release.
• Sanitary waste management prevents water contamination, controls disease vectors, and is inaccessible to children.
• Sanitation facilities should be culturally acceptable, affordable, maintainable, private, convenient and may allow resource and energy recovery.

Sanitation Systems and Technologies

• Sanitation systems can be onsite or offsite and use either wet or dry methods.
• Unsanitary onsite systems include open pit and overhung latrines; sanitary ones feature ventilated/improved pits and composting toilets.
• The ventilated/improved latrine is a dry tech involving excreta seeping into the soil, with solids broken down biologically, vented to release gasses.

Wet System Technologies

• Pour-flush toilets are inexpensive, use little water, minimal odor, and can be in-house.
• Cistern flush toilets are for areas with continuous water; they discharge directly into sewage or septic systems.
• Septic tanks use a vent pipe to regulate air pressure, allow solids to accumulate, and are 95% effective in removing solids.

Offsite Sanitation

• Components of Offsite Sanitation includes cartage fees, sewerage for treatment facilities, conventional and shallow sewerage

Sewage Treatment Facility

• Sewage disposal involves different methods of getting rid of sewage.

Biological Treatment

• Biological sewage treatment can be done through means of activated sludge system

Waste Stabilization Ponds

• Stabilization bonds use the natural way of treating wastewater biologically
• There are 3 steps (anaerobic ponds, facultative ponds and maturation ponds)