Prof. Jorge,
Below is my 8th NU12.
Regards,
Michael Ligayo
Michael Ligayo
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REDUCTION OF COLOR IN WASTEWATER USING WASTE AGRICULTURAL MATERIALS
Background
Almost every industry uses dyes and pigments to color its products. Color makes the products look more attractive and pleasing to the eye. According to research, color has an effect on how the product will sell in the market. Thus, dyes and pigments play an important role to various industries. This is most especially true to the textile industry, one of the major industries of Asia. Without color, textile products will not be attractive to its consumers. In almost all cases, colors give clothing the designs and patterns that make it unique and attractive. Nigam, et. al, 1995, reported that the annual world production of dyestuffs is about 640,000 tons. Of this amount, 56% are textile dyes, 23.5% are pigments, and 14% are dyes for paper and the rest for various other uses. There are approximately about 10,000 dyes and pigments available in the market. In the Philippines, it was reported in the Philippine Statistical Yearbook 2000 that in 1996, there are about 556 registered textile establishments and the ratio between the products per by-products sold were 27,033,239. In the following year, the number of registered textile establishments increased to 583 and the products per by-products sold were 30,571,487. The trend in these numbers only indicated that the textile industry is a continually growing local industry.
However, despite the many uses of textile to various industries, textile color, an effluent characteristic, which is easily detected and readily traced back to its source (Dogan, 2000), is a visible indicator of pollution (Porter, 1999).
McKay (1982) stated that in the textile industry, about 10-20% of the total mass of dyes used in the processes is lost as effluents through incomplete exhaustion and washing. He further mentioned that the current treatment processes for dye-containing effluents are only capable of removing about half of the lost dyes, the rest find their way into the environment, either as dissolved or suspended in water. On a daily basis, the world produces about 1 to 2 million gallons of textile wastewater. The amount of effluent produced per pound of fabric processed is about 10-35 gallons (Allen, 1999). In the Philippines, Saluta (2000) reported that textile mills discharge about 42,000 liters of wastewater on a daily basis. Despite all these wastewater produced, the textile industry only reuses about 10% of its process water (Lund, 1971).
Effect of Color on Water
Color in the body of water creates a "blanket" on its upper surface, thereby, preventing the entry of valuable sunlight to the bottom of the body of water, where most photosynthetic plants live. This results to an anaerobic condition at the bottom of the body of water and prevents production of oxygen by photosynthesis. Oxygen is valuable to the reduction of the total organic load of the body of water. Existing Philippine regulations on color include the Department of Environment and Natural Resources Administrative Order No. 34 and No. 35 (otherwise, known as DAO 34 and DAO 35, respectively). The former dealt with the revised water usage and classification, while the latter dealt with the revised effluent regulations.
Alternative Technologies
Today, the methods of color removal from industrial effluents include biological treatment, coagulation, flotation, adsorption, oxidation and hyperfiltration. Among these treatment options, adsorption appears to have a considerable potential (Porter, 1999). Weber (1978), as cited by McKay (1999), enumerated the advantages of adsorption over the other methods. These include: (1) less land area (half to quarter of what is required in a biological system), (2) lower sensitivity to diurnal variation, (3) not being effected by toxic chemicals, (4) greater flexibility in the design and operation, and (5) superior removal of organic contaminants.
Present technology uses activated carbon as adsorbent for the removal of color, taste, odor and many other organic contaminants, specifically, those that are biologically resistant. Others use agricultural wastes, such as: rice husk, bark and cotton waste (McKay et. al, 1999); corncob (El-Geundi, 1990); rice hull (Saminiano, 2002); coconut husk (Manalo, 2001); wood shavings (Abo Elela, et. al, 1987); sunflower stalk (Sun et. al, 1997); corn pith (Fegi, Jr., 2001); natural clay (Hawash, et. al, 1993); peat, bentonite and fly ash (Ramakrishna, et. al, 1997); perlite (Dogan et. al, 2000); and lignite (Allen, et. al, 1989). One of the new possible adsorbent is sugarcane bagasse. Generally, sugarcane bagasse is used as an energy source in the sugar industry. However, the amount of sugarcane bagasse produced is so much that many sugar factories treat it as solid waste. The Philippine Statistical Yearbook 2000 reported that in 1999, about 375,300 hectares of land are being allotted for sugarcane. The annual production of sugarcane in the Philippines in the same year is about 22,292,900 metric tons, costing about 18280.2 million pesos. Of this total production, Hugot (1972) reported that about 24-30% on mass basis is being disposed as bagasse.
The Proposal
The Philippines is rich in agricultural crops and ultimately, on agricultural wastes, being an agriculturally based country. Further, it is oftentimes the problem as to where our farmers would dump the agricultural waste. For example, in Bay, Laguna (where I live), farmers are prohibited to burn the agricultural wastes in an effort not to pollute the air. However, the agricultural wastes are left to rot in the garbage and in the farmlands. This is part of the problem that is causing the dumpsite (near San Pablo, Laguna) to get over-filled. If we are going to use the agricultural wastes to reduce color in the effluents of factories, these agricultural wastes can be of great use. This is especially since Laguna is rich in factories that release color-rich effluents. (An example of this factory is the Litton Mills that creates jeans.) The benefits of utilizing these wastes would be a better Laguna Lake – having an aerobic condition – and would probably have prevented the recent fish kill.
The Process
The process of utilizing these agricultural wastes is pretty simple. The wastes should be dried and ground to powder form. Then, then can be introduced to the wastewater at certain concentrations depending on the darkness of the color of the water. Heat can be introduced to hasten the adsorption. Finally, filtration can be applied to remove the powdered agricultural wastes together with the chemicals that cause the color of the water. The process works best with organic chemicals such as dyes. <tanong ako sa iyo paano maiaapply to the deceased?> 4
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