Defferentiate between solid waste and liquid waste by
giving examples. (3 points)
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Answer:
SOLID WASTE - Solid wastes include solid portions of the discarded material such as glass bottles, crockeries, plastic containers, metals and radioactive wastes. The solid wastes may be biodegradable or non-biodegradable. The biodegradable solid wastes are agricultural wastes, food wastes, paper, food processing by products, manure, yard wastes etc. The non-biodegradable wastes includes plastic, metals, synthetic materials, radio active waste etc.
The solid waste management involves disposal of solid waste to land (or ocean) or recovering and reproducing useful substances from the waste through recycling.
The entire methodology of solid waste management is based on:
Collection of Waste
Disposal
Resource recovery
Collection of Waste:
The solid wastes are usually collected by a covered truck.
Disposal of Waste:
After the collection of wastes, the wastes are disposed of by any one of the methods as follows:
Dumping
Sanitary landfills
Incineration
pyrolysis
Composting
Bio gas technology etc
Resource recovery (Recycling):
By the process of recycling, a number of useful products can be obtained from the solid wastes.
Some important products obtainable from solid wastes are described below:
Waste papers and cardboards from sugar cane bagasse can be used for the preparation of unbreakable dolls, packing cardboards etc.
Metals can be recycled from the industrial scrap.
Waste glasses can be used for the preparation of new glass bottle.
Electricity can be generated through incineration.
LIQUID WASTE - Liquid wastes are the liquid part of the waste material. Liquid waste includes effluents of industries, fertiliser and pesticide solutions from agricultural fields, leachate from landfills, urban runoff of untreated waste water and garbage, mining wastes etc. The liquid waste may contain nontoxic inorganic substances or toxic organic substances.
Some important liquid waste management methods are as follows
Sewage treatment - This process involves the following methodology:
Dilution
Mechanical treatment
Biological treatment
Chemical treatment
2. Removal of ammonia- The treatment of industrial effluents in Effluent Treatment involves chemical or primary treatment (by methods of neutralization, sedimentation, coagulation, precipitation etc.) followed by biological or secondary treatment (by activated sludge and trickling filter method) and tertiary treatment (by methods of ion exchange, reverse osmosis, chemical oxidation).
3. Effluent water can be used to grow algae and aquatic plants to produce biomass for biogas plants.
4. The sewage with organic nutrients is stored in specially constructed shallow ponds called as oxidising or stabilizing pond. In the pond, green algae and bacteria grow in presence of sun light, consuming organic nutrients. This water contains enough nitrogen, phosphorous and potassium and is highly helpful for the growth of plants.
GASEOUS WASTE - Gaseous waste are waste products in gas form resulting from various human activities like manufacturing, processing, material consumption, biological processes etc. The gaseous wastes include carbon dioxide (CO2), methane (CH4), chlorofluorocarbon (CFC), oxides of nitrogen (NOx), carbon monoxide (CO), oxides of sulphur (SOx) etc. These gaseous wastes can cause serious environmental hazards. Therefore, it is highly essential to take appropriate steps for the proper management and control of gaseous wastes in the environment.
Some of the control measures are:
The gaseous pollutant like SO2, H2S, NH3 etc can be removed by absorption in (using appropriate liquid) wet scrubbers.
The industries should use precipitators, scrubbers and filters to check production of particulate matter.
There should be large scale of plantation which will reduce CO2 level and increase O2 level of atmosphere.
Air cleaning devices like gravity settlers, cyclone separators, wet collectors, electrostatic precipitators etc. should be used for the cleaning of air before their discharge into atmosphere.
Public awareness should be created regarding hazards of air pollutant accumulation in environment.
Hope this helps
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