Impact of Municipal Solid Waste on Environment & Health By Dr. Ajay Krishna, MBBS., DCH., MD. Assistant Professor, Dept. of Community Medicine, Patna Medical College, Patna

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.   Strictly speaking Solid Wastes should not contain night soil. The per capita daily solid waste produced ranges between 0.25 to 2.5 kg in different countries.

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

Sources of solid wastes : Street refuse : collected by street cleaning service or scavenging e.g. : leaves, straw, paper, animal droppings.   Market refuge: contains putrid vegetables and animal matter. Stable and cowshed refuse. Industrial refuse: contains wastes ranging from completely inert materials to highly toxic and explosive compounds. Domestic refuse: contains ash, rubbish and garbage.

Garbage is waste matter arising from the preparation, cooking and consumption of food. It consists of waste food, vegetable peelings and other organic matter.

Storage of solid waste: The galvanized steel dustbin with close fitting cover is ideal.   The output of refuse in India is approx – 1/10 – 1/20 cft. Per capita per day. So for a 5 member family it is around ½ cft per day. If collection is done every 3 days then a bin with a capacity of 1 ½ - 2 c.ft. would be adequate. Public bins : cater to a large no. of people. They are kept on a concrete raised platform and have no covers.

Collection of solid wastes: Method depends on the funds available.   House to house collection is the best method but in India we do not have such a system.  Method of disposal: The principal methods are: Dumping Controlled Tipping or sanitary land fill Incineration Composting Manure Pits Burial

Dumping : Easy method of disposal of dry solid waste 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 pollution of surface and ground water.  

A WHO Expert Committee (1967) condemned dumping as “ a 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”.

Controlled tipping is of three types: Controlled Tipping: Most satisfactory method where suitable land is available. Solid waste is placed in a trench, compacted and covered with earth at the end of the working day.   Controlled tipping is of three types: Trench method: Long trench 2 – 3 m deep and 4 – 12 m wide is dug. Refuse is compacted and covered with excavated earth. Ramp method: Suited when terrain is moderately sloping. Area method: Used for filling land depressions, disused quarries and clay pits.

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

Incineration : Refuse can be disposed off hygienically by burning or incineration, however, hospital refuse which is dangerous is best disposed off by incineration.   Practiced in several of the industrialized countries. Not a convenient method in India as refuse contains a fair amount of fine ash which makes burning difficult.

Composting: Method of combined disposal of refuse and night soil or sludge. It is a process of nature where organic matter breaks down under bacterial action resulting in formation of relatively stable humus like material called the Compost which has considerable value as a manure.

How composting takes place? The principal by product when refuse and night soil is mixed are – carbon dioxide, water and heat. The heat produced is 60 degree centigrade 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.

Manure Pits: In rural areas in India, there is no system for collection and disposal of refuse. Refuse is thrown around houses resulting in pollution of the environment.

Manure pits can be dug up by different house holds where cow dung, garbage, straw and leaves can be dumped and covered with earth after each day’s dumping.   Two such pits will be needed , when one is closed, the other will be in use. In 5 – 6 months time, the refuse is converted into manure which can be returned to the field. This method of refuse disposal is effective and relatively simple in rural communities.

Burial: This method is suitable for small camps. A trench 1.5 m wide and 2 m deep is excavated and at the end of each day the refuse is covered with 20 – 30 cms. of earth. When the level in the trench is 40cms from ground level, the trench is filled with earth and compacted and a new trench is dug out.  The contents can be taken out after six months and used in fields.  If the trench is 1m in length for every 200 people, it will be filled in about 1 week.

Public Health importance:   A municipal waste if contaminated with excreta is a source of infection. The health hazards of improper waste disposal are: Soil Pollution. Water Pollution. Contamination of foods. Propagation of flies.

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

Occupational hazards associated with waste handling Infections : - Skin and blood infections resulting from direct contact with waste, and from infected wounds. Eye and respiratory infections resulting from exposure to infected dust, especially during landfill operations. Different diseases that results from the bites of animals feeding on the waste. Intestinal infections that are transmitted by flies feeding on the waste.

Chronic diseases: - Incineration operators are at risk of chronic respiratory diseases, including cancers resulting from exposure to dust and hazardous compounds. Accidents: - Bone and muscle disorders resulting from the handling of heavy containers. Infecting wounds resulting from contact with sharp objects. Poisoning and chemical burns resulting from contact with small amounts of hazardous chemical waste mixed with general waste. Burns and other injuries resulting from occupational accidents at waste disposal sites or from methane gas explosion at landfill sites. Source - Adapted from UNEP report, 1996

The Sanitation Barrier Food Fingers Fomites Flies Faeces

Whatever method may be used by the municipal corporations but till and until the public mind set regarding waste production and its hygienic disposal is changed, the situation will more or less be the same.

Thanks