EXCRETA, SEWAGE, REFUSE DISPOSAL

Arnel V. Herrera, MD FPAFP

Excreta: Human Feces and Urine Contains nutrients:Nitrogen (N) 12 gPhosphorous (P) 2 gPotassium (K) 3 gOrganic Matter 90 g Most organic matter in feces Most N and P (70-80 %) in urine. K equally distributed between urine and feces.

Nutrient excretion by humans is directly linked to diet

We excrete the same amount of nutrients that we take up in our diet (except for children who retain a small proportion for growth of bones)The amount of excreted nutrients by one person is the same amount that is needed as fertiliser to grow the food for that personNNPPDietExcreta

Excreta: Human Feces and UrineDry SystemsHuman (sanitary) waste in settings where water use is limited by preference or lack of indoor plumbing for water supply and liquid waste (sewage) disposalPre-treatment prior to use Nutrients and organic matter are: detrimental in surface water, eutrophication causes anoxia and fish killsBeneficial on land as fertilizer, soil conditioner, land stabilizer Potential for excreta misuse and environmental pollution is great if there is no proper attention to management plans and human behavior considerations

Public Health importance:The health hazards of improper excreta disposal are:Soil Pollution.Water Pollution.Contamination of foods.Propagation of flies.

Diseases resulting from contamination are :Typhoid and paratyphoid fever.Diarrheas and Dysenteries.Cholera.Hook worm and other intestinal parasitic diseases.Viral hepatitis.Poliomyelitis and other viral infections.

Approved types of toilet facilities:LEVEL I :Non-water carriage toilet, ex. Pit latrine, VIP and Bored Hole latrine.Toilet facilities requiring small amounts of water to wash into the receiving space, ex. Water sealed latrineLEVEL II: On-site toilet of water carriage type with water- sealed (flush type) with septic tankLEVEL III:Water carriage type connected to sewerage system to treatment plant

Excreta DisposalCriteria for acceptable excreta disposal facilitiesSanitarySimple, cheap and easy to construct with local materialsEasy to maintainWith adequate protection against elements and provides desirable privacyAcceptable to the users

Methods of Excreta DisposalCat-hole LatrineStraddle Trench LatrineSanitary Pit privy Level 1- Pit type- VIP4. Bored-hole Latrine Level 15. Water-sealed Latrine Level 16. Chemical Toilet7. Pail System8. Overhung Latrine

Cat-hole latrineSimplest methodA small hole is excavated using any suitable implementNot used as regular excreta disposal facility

Straddle Trench LatrineA trench is dug to a depth of about 2 feet.An improvised shovel is used to cover the excrement after each defecation.When the trench is filled to within 6 inches from the top, the content is sprayed with oil and covered with soil and compacted.

Pit PrivyA pit is dug to a depth of 4 6 feet. A floor cover at the top of the pit is provided together with a riser, seat and self-closing lid all made in as fly tight as possible.A vent is provided with fly screen

Contents of Pit PrivyPeople use old newspapers for anal cleansing

Ventilated Improved Pit

Bored-hole LatrineDeep holes bored into the earth with mechanical or manual earth-boring equipment.The hole is provided at the top with a cover.Foot rest are sometimes provided to facilitate squatting.

Water-sealed LatrineA pit privy modified to include a bowl made of durable material, with a P or S shaped trap which forms a water seal when water is added.Water is used for cleaning and about 2-3 liters of water is used for flushing the content.

Chemical ToiletUtilizes the principle of liquefaction of organic matter using caustic soda (sodium hydroxide) to liquefy the fecal material and destroy bacteria.After several months of operation, the liquefied matter together with the spent chemicals are removed and drained.

Pail SystemAlso known as Box and Can Privy or Bucket LatrineRegular removal and disposal of waste in a sanitary manner.Burial of contents at least 12 inches from the ground, to prevent access to flies or escape of adult flies.

Overhung LatrineConsists of a superstructure provided with latrine floor on top of wooden piles above the water.The disposal of human wastes consists essentially of defecation into the water. Unsanitary

Sanitary SewageLiquid or Wet Systems, Septic TankTypical for human waste in settings where there is piped, household water supply and sanitary waste disposal using water.About 99.9% water and 0.10% solidsTypically consists of washing water, feces, urine, laundry waste and other material which goes down drains and toilets from households and industry.

Septic Systems

Septic Tank SystemWet system with collection into a subsurface tank, separation (settling) and anaerobic digestion of solids and discharge of liquid effluent via perforated pipes into subsurface soil.Widely used in developed and developing countries.Often fail (eventually) due to poor site conditions, poor installation and obstruction.

Problems encountered using communal toilets or public toilets:No dedicated service providersDue to lack of running water and a situation of poor water availability people come only with a mug of water for anal cleansing but not flushing.No lighting facilities lead to poor usage by women.When septic tank is filled up it is not emptied quickly and hence usage goes down.

These situations lead to open defecation.

GreywaterOther wastewater from human activityNot directly from human feces and urineWastewater from washing, bathing, etcTreatment and reuse for irrigation and ground water rechargeGreywater contains some P (from detergents) but little N

Characteristics of Human Wastes

Ecological Sanitation EcosanTreats human excreta as a beneficial resourceExcreta are confined and processed on site until they are free of pathogenic (disease-causing) organismsSanitized excreta are then recycled by using them for agricultural purposes. Key features of ecosan: Prevent pollution and disease caused by human excretaManage human excreta as a resource rather than as a waste productRecover and recycle water and nutrients

Guiding principle for fertilisation with ecosan productsWe are fertilising the soil, not the plant!Ecosan products not to be used on plants directly but on the soil in which the plants are grownUrine is applied in a furrow about 10 cm. away from the plants

Role of feces as an organic fertiliserHigh concentrations of P and KOrganic matter is beneficial because:Improves soil structureIncreases the water-holding capacity and ion-buffering capacity of the soilSupports soil microorganisms by serving as an energy sourceAvoid feces as fertiliser for growing vegetables which are eaten raw

Visual evidence for agricultural benefits of ecosan productsurinefaeces & urinenone compost improved soiluntreated soilafter one week without water Maize (corn) Source: GTZ presentations

Source: Morgan (2007)without ecosan productswith ecosan productsThe dark green colour comes from more nitrogen uptake

Increased yield for maize (corn) with ecosan productsSource: Morgan (2007)

Hormones and pharmaceutical residues in ecosan products (mainly urine) are not really a problem for reuse becauseVegetation and soil microbes can degrade hormones and pharmaceuticalsIt is far better to recycle urine and faeces (with their hormones and pharmaceuticals) to arable land than to flush them into recipient waters Urine of hospitals is not recommended to be used in agriculture.

What if people are still really worried about eating food fertilised with human excreta?You can use human excreta also on other types of crops, which are not eaten by humans, e.g.FlowersPotted plantsFibre-producing plants (e.g. hemp)Oil-producing plants, e.g. olive treesTrees

Sewage Treatment Systems

Subject sewage to physical, biological and chemical treatment processesSeparate settable solids from remaining liquidBiologically degrade ands stabilize organic matterBiologically reduce pathogensPhysically and chemically disinfect pathogensOxidize and stabilize non-settleable organic matter and nitrogen in the remaining liquidOr denitrify (biologically convert nitrogen to N2 gas)

Sewage TreatmentPhysical and biological treatment

direct injection of liquid fertiliserdried faeces - soil amelioration)irrigationurban agriculture composting with organic wasteAgricultural Useurban agriculture

AquacultureWastewater treatment by aquatic plants and fish with nutrient recyling by human consumptionOffers high quality protein at low costPredominantly in Asian countriesFish production of 1-6 tons/year achieved

Advanced (Tertiary) Sewage TreatmentUses physical and chemical processesRemoves nitrate and phosphateExpensiveNot widely used

Refuse DisposalGeneral term applied to solid and semi-solid waste materials other than human excreta.

Solid Wastes include Garbage (food wastes)Rubbish ( paper, plastics, wood, metal, throw away containers, glass). Demolition products (bricks, masonry, pipes). Sewage treatment residue (sludge and solids from the coarse screening of domestic sewage). Dead animals, manure, other discarded materials.

Paper: 50%

Sources of solid wastes : Street refuse : collected by street cleaning service or scavenging, such as leaves, straw, paper, animaldroppings. Market refuge: contains putrid vegetables and animalmatter. Stable and cowshed refuse.

Industrial refuse: contains wastes ranging from completelyinert materials to highly toxic and explosive compounds. Domestic refuse: contains ash, rubbish and garbage.

Solid waste if accumulated anywhere is a health hazard because : It decomposes and favors fly breeding. It attracts rodents and vermin. Possibility of water and soil pollution. Unsightly appearance and bad odors.Solid waste accumulation increases chances of vector borne diseases.

Storage of solid waste:

Home Refuse Disposal MethodsCompostingBurningFeeding to animals

CompostingMethod of combined disposal of refuse and night soil. It is a process of nature where organic matter breaks down under bacterial action resulting in formation of relatively stable humus.

CompostingThe principal by product when refuse and night soil is mixed are CO2, water and heat.The heat produced is 60 C or higher over a period of several days which destroys eggs and larvae of flies, weed seeds and pathogenic agents.Compost is a very good soil builder and has major plant nutrients.

BurningInvolves open burning in the ground or drumProhibited because burning household waste release toxic substance known as dioxins

Feeding to animalsLeft-over foods can be made use by feeding to pigs, chicken, other poultry and livestock.

Collection of community solid wastes: House to house collection is the best method thendispose thru the following principal methods: Dumping Controlled Tipping or Sanitary Land Fill Incineration

Dumping : Easy method of disposal of dry solid waste. Land reclamation is often done by this method. Refuse decreases considerably in volume due to bacterial action and is gradually converted to humus.Drawbacks of open dumping are: Refuse is exposed to flies and rodents. Source of foul smell and unsightly appearance. Loose refuse is dispersed by the action of wind. Drainage from dumps contributes to pollutionof surface and ground water.

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Controlled Tipping: Most satisfactory method where suitable landis available. Solid waste is placed in a trench, compactedand covered with earth at the end of the working day. Require impermeable barriers to stop escape of leaches: can cause problem by overflow Gases produced by decomposing garbage needs venting

Controlled tipping is of two types: Trench method: Long trench 2 3 m deepand 4 12 m wide is dug. Refuse is compacted and covered with excavated earth. Area method: Used for filling land depressions, unused quarries and clay pits.

Why controlled tipping is a good method? Chemical, bacteriological and physical changesoccur in buried refuse. Temp. rises to over 60 degrees within 7 days andkills all the pathogens and helps in decomposition. Cools down in 2 3 weeks and within 4 - monthscomplete decomposition of organic matter takes place.

IncinerationAdv: Refuse is disposed off hygienically Preferred method for hospital refuse- Solves space problem but.Disadv: Produces toxic gasesExpensive

Average daily human excretion of nutrients. A normal stool is 75% water and 25% solid. Color is brown because of stercobilin and urobilin that comes from bilirubin. The odor is aromatic upon defecation due to indole and skatole products of fermentation and putrefaction in the large intestine. Urine: color amber/straw, odor aromatic upon voiding, pH is acidic**Eutrophication: The process by which a body of water acquires a high concentration ofnutrients, especially phosphates and nitrates. These typically promote excessive growth of algae. As the algae die and decompose, high levels of organic matter and the decomposing organisms deplete the water of available oxygen, causing the death of other organisms, such as fish. Eutrophication is a natural, slow-aging process for a water body, but human activity greatly speeds up the process.*Footnote: out of 15 million households, 5 million households dont have a sanitary toilet here in the Philippines*Hookworms MOT is skin penetration, .25cc of blood per hookworm causes IDA. Other intestinal parasites ascaris and trichiuris***Can used hand or garden trowel, 6-8 inches deep and 4-6 inches in diameter, then cover it with soil after defecation. Can be source of spread of diseases use only during camping or during emergency situations if there is no available toilet facility. Ideally at least 200 ft. away from water source or camping site. *Much improved version of cat-hole latrine and 1 straddle trench could accommodate 50 people in 1-3 days. More sanitary and less odorous, must be 200 ft away from water source, camp site and trail *LEVEL I. Dry material is used for cleaning, such as papers, corn husk, or corn cubs. If the pit is already full, it is closed and wait for 2 years, the contents will undergo anaerobic decomposition, also you have to consider the lifespan of the ascaris ova which is 1-1 years in the meantime you will make another pit and just transfer the superstructure. After 2 years excavate all the contents, sundried it and could be used now as fertilizers or soil conditioner. One disadvantage, there is danger of you falling inside the pit, the squatting plate must be made of sturdy material**LEVEL I. Same principal with pit privy, dry materials is used for cleaning, wait for 2 years then excavate, sundried and used as fertilizer or soil conditioner. It is improved because you dont need to squat and there is no danger of you falling inside the pit. *LEVEL I. The hole is 10-18 inches in diameter, 15-35 feet deep.*LEVEL I. Same principle with pit privy, closed if the pit is full, make another pit, wait for 2 years then excavate, sundried the content and used as fertilizer or soil conditioner. Dry materials must not be used because of danger of obstruction. During winter water-sealed latrine must not be used because water will freeze. *6-9 months of operation*Level II*In cases of obstruction the outlet is the one that is clogged effluent can not get out. Scum is a filmy layer of impure matter that forms or rises to the surface of a body of water. *Percolation- allow liquid to pass thru, Leaching to empty drain, to remove soluble substances from percolating liquid********Nitrogen gasis slightly lighter than air and slightly soluble in water.*Primary Treatment - the simplest, and least effective, method of treatment is to allow the undissolved solids in raw sewage to settle out of suspension formingsludge. Bar screen or metal screen allows removal of gross debris such as papers, rags, wood, used condoms, sanitary napkins. Ideally the gross debris must be disposed by incineration or dumped in sanitary landfill. Grit chamber- gravel, sand and heavy materials settle out at the bottom. The solid portion will settle down and forms the sludge. In some the effluent pass from primary treatment tosecondary treatment. Here the effluent is brought in contact with oxygen andaerobic microorganisms. They break down much of the organic matter to harmless substances such as carbon dioxide. Afterchlorinationto remove its content of bacteria, the effluent from secondary treatment is returned to the local surface water.

*People no. 1 producer of waste*Garbage is waste matter arising from the preparation, cooking and consumption of food. It consists of waste food, vegetable peelings and other organic matter. Most solid waste is in the form of papers.

*Recycle 1 ton of paper we are saving 17 trees. If half of the worlds paper are recycled 20 million acres of forest is conserved.*Accumulation of solid waste causes obstruction in the drainage system, we dont want another ondoy. Increase incidence of typhoid fever, hepatitis A, and diarrheal diseases.*Trash bin containers could be made of plastic or galvanized iron but most ideal is made of hard plastic with label and cover*Any household waste that cannot be dispose to the trash bin can be disposed to the following manners* Humus - organic substance that provides nutrients for plants and increases the ability of soil to retain water. *Dioxins linked to cancer, developmental and reproductive disorder*Dumping is the most unsanitary method that creates public health hazards, a nuisance, and severe pollution of the environment. Dumping should be outlawed and replaced by sound procedures.

*Problems of air pollution may arise even if you use state of the art incinerator*