WAYSEland: Waste Treatment

Waste treatment

What is waste treatment?

Waste treatment refers to the activities required to ensure that waste has the least practicable impact on the environment. In many countries various forms of waste treatment are required by law.

Some examples of waste treatments are:

1.Disposal of wastes
Disposal of waste includes land filling, composting, and incineration. Disposal of waste here is defined as getting rid of waste, especially non-biodegradable waste. Because of this broader sense of word, gasification is, by right, a method of waste disposal.

-Composting
Composting is the aerobic decomposition of biodegradable organic matter. It was originally used for creating garden-ready soil. Nonetheless, it is now an important way to get rid of solid waste that is biodegradable in nature. However, the potential of this method has not been realised, with only 8% of the more than 60% of materials being treated this way in the US. People often feel that composting is complicated. However, “passive composting”, that is, leaving the material to rot [pun intended] serves as well as active composting [making sure that the condition is close to perfect for the aerobic bacteria by adding extra chemicals and/or ingredients]

In our opinion, composting is important as it recycles or downrecycles or "downcycles" organic household and yard waste and manures into an extremely useful humus-like, soil end-product called compost. Some examples are fruits, vegetables and yard clippings.
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Composting is widely believed to speed up the natural process of decomposition appreciably as a result of the raised temperatures that often accompany it. (The elevated heat results from exothermic processes, and the heat in turn reduces the generational time of microorganisms and thereby speeds the energy and nutrient exchanges taking place)

-Incineration
Incineration involves burning materials and it is therefore classified as “Thermal Treatment”. There is a debate over the environmental and health risks incinerators pose to the environment as in some countries, there is no material separation, which means that hazardous, recyclable materials as well as bulky materials are thrown into the incinerator. This might cause poisonous fumes, especially associated with burning of plastics, to be emitted and even non-toxic gases, such as carbon dioxide, are responsible for the formation of acid rain, as well as the greenhouse effect [Carbon Dioxide is one of the Greenhouse Gases]. Incineration reduces the mass of material by 95-96%, so it is often used in conjunction with land filling as it reduces the volume needed for land filling.

Incineration has particularly strong benefits for the treatment of certain waste types in niche areas such as clinical wastes and certain hazardous wastes where pathogens and toxins can be destroyed by high temperatures. Examples include chemical multi-product plants with diverse toxic or very toxic wastewater streams, which cannot be routed to a conventional wastewater treatment plant. However, due to the high cost needed to carry out incineration, it is not advisable to use this method as a treatment for waste.

-Landfill
Land filling is the method of burying your waste underground. This is the oldest and most popular method of waste disposal by fair, being widely used in many countries like Indonesia and the Philippines, because it is relatively inexpensive, unlike incineration. Landfills are also used to dispose of radioactive materials, often rendering the land unusable, because of the possible effects of radioactivity on humans as well as the environment.
Even if it’s not radioactive waste, land filling can have potentially harmful effects of the environment, like the contamination of groundwater, the attraction of pests like rats, and the production of gas. This might cause buildings built on the landfills to experience liquefaction during earthquakes.

We feel that the method of landfillingmay not be very feasible as huge areas of land are needed. For countries like Singapore, being a small country as it is, not much land can be used for landfilling. Also, in the process of landfilling, fatal accidents may occur. (Eg:scavengers buried under waste piles) ,infrastructure damage. (Eg: damage to access roads by heavy vehicles) and lastly, pollution of local environment. (Eg: such as contamination of groundwater and/or aquifers by leakage and residual soil contamination during landfill usage, as well as after landfill closure.

-Fun Fact:
U.S. landfills consist of 40% to 50% paper waste, 20% to 30% construction debris, and 1.2% disposable diapers
Windrow composting makes use of the same principal as composting [ie: breaking down biodegradable waste to form compost as fertilizer for the plants], except that it is on an industrial scale and it is similar to active composting [ie. People have to calculate how much carbon-rich materials and nitrogen rich materials there are, moisture etc.etc. ] There are machines that turn the materials for windrow composting for better oxygen levels and moisture content for the aerobic bacteria to act upon the waste.

2. Reverse Osmosis-The treatment of water
NEWater is reclaimed water which has gone through treatment in NEWater Plants which consists of four processes namely Micro Filtration, Reverse Osmosis, Water Conditioning and Ultraviolet Disinfection, before turning into pure water. It can be used for potable and non-potable purposes, mainly for wafer fabrication and air condition cooling towers.
NEWater was first implemented in the United States. It has been in place for more than 20 years.

In Singapore:
Singapore’s water problem- WHY WAS NEWATER INVENTED?

· There are many answers to this question. One answer is that Singapore’s daily water consumption keeps increasing daily. As Singapore’s population increases and the economy grows, more water is needed to keep factories running and people living. More and more people are immigrating to Singapore, and more and more businesses are being set up. Also, as water is so easily accessible – just turn on the tap and water will flow – more and more people are taking it for granted. They use water excessively without a second thought. All this contributes to the steadily growing water consumption.

· Another answer is that our previous sources of water are diminishing. This is because one big source of water for Singapore is water from Johor, Malaysia. We have 2 treaties with them, one expiring in 2011 and the other, in 2061. As 2011 draws near, Malaysia and Singapore are still not able to agree on terms for another water treaty. Malaysia is negotiating for higher prices, while Singapore wants everything to remain the same. If we could not come to an agreement by 2011, Singapore would be doomed.

· The Singapore government also realized that depending on other countries for water put us in a very vulnerable position that we did not want to be in. If Malaysia suddenly decided to cut off our supply of water, what would we do?

· This led to the conclusion that other sources of water needed to be created. After a long search, the government came up with NEWater to serve the purpose of the being the fourth national tap to fulfill the growing water consumption.

-Process of NEwater:
1. First water goes through Micro filtration. Micro filtration consists of many tiny fibers, which act like filters. Each fiber can filter particles up to 0.02 microns (the unit used to measure micro-organisms) in size. During Micro filtration, dirty water passes through the fibers. Solids, most bacteria and many harmful organisms are trapped in the tubes. Micro filtration also ensures a good stream of steady flowing water (water particles are able to pass through) to prevent blockage and clogging up.

2. Next, the water undergoes Reverse Osmosis. Reverse Osmosis applies pressure such that the water would flow from the concentrated side, to the less concentrated side through a semi-permeable membrane. This process removes the dirty contents of water, like nitrate, chloride (the nasty tasting water in the swimming pool is full of them), sulphate etc.

3. It also disinfects the water, and removes some of the pesticides in the water from the Micro filtration process. The Reverse Osmosis membrane has a pore size of 0.0001 microns (*gasp*) and through this process; about 95% of the dissolved solids in the water are removed. The Reverse Osmosis process also removes viruses.
4. Then, as a safety precaution back up if the Reverse Osmosis surprisingly fails, the Ultra violet Rays in the next step, Ultra Violet disinfection, will wipe out any harmful particles in one zap.

5. Finally, the fully cleansed water is mixed with water from the reservoir to give it a “water taste”, as it is too clean such as it does not have any taste at all. The NEWater is now ready to be drunk.

Sources: http://schools.moe.edu.sg/rgps/html/home.htm