Increasing garbage and its proper disposal management are among the major headaches of municipalities today. Most view garbage as a cause of the floods that wreak havoc during typhoons, such as the Ondoy typhoon, which happened September 2010.
Even before Ondoy and Pepeng hit the Philippines, the country had been plagued by floods. However, what set apart the two recent catastrophes is their gravity. In six hours, Metro Manila received a month's worth of rainfall, according to thePhilippine Atmospheric, Geophysical, and Astronomical Services, Administration (PAGASA), the worst ever recorded in history.
Although many argue the cause of Ondoy's disaster as a confluence of various factors, many people also concluded that the increasing garbage in the Metro was a major contributor to the heavy flood.
This is one of the reasons why a growing number of municipalities are attracted to technologies that would introduce innovative ways of reducing garbage and disposing of it properly.
Currently being used by municipalities is the waste-conversion technology, among the most popular by-products of which are the concrete blocks, better known as “hollow blocks.” The technology is popular because it does not only reduce garbage but it also helps in combating climate change. Moreover through this initiative, municipalities are also attempting to challenge the quarrying activities done within their respective area.
The production of commercially-available concrete is estimated to produce more than six billion pounds of carbon dioxide (CO2) annually. If less concrete is manufactured, then CO2 emissions will also be lessened. The energy-intensive process of manufacturing conventional concrete makes the technology dirty because of the CO2 emissions, thus contributing to climate change.
To briefly explain the technology, plastic wastes and styrofoam containers are segregated from the garbage to be fed into a diesel-powered pulverizing machine, which pulverizes the plastics into tiny bits and pieces. These are then mixed into a wet mound of cement and sand. The mixture will then be poured into the molder up to its brim. The molder is then lifted upside down to eject the freshly made hollow block.
One of the municipalities producing these alternative bricks is Teresa, Rizal. According to Teresa's solid waste management program chief Marlon Pielago, the blocks they produce are not as strong as the ones available commercially, and are not intended to replace the commercially produced ones.
Other cities and municipalities using the same and other related concrete-producing technology are Bantayan in Cebu; Sto. Tomas, Davao del Norte; Laoag City, Ilocos Norte; and Mandurriao district in Iloilo City.
Related technologies on the international scene
Bitublock
While the concrete blocks produced locally are not meant to replace the commercial hollow blocks, there is one technology that provides exactly the opposite.
This is "Bitublock," an invention by Dr. John Forth of the School of Engineering, University of Leeds. “Our aim is to completely replace concrete as a structural material,” he said.
Made from 100% waste material such as sewage sludge, metal slag, recycled glass, pulverized fuel ash, and incinerator ash, Bitublock boasts that it is six times as strong as the regular hollow block.
In making the Bitublock, the secret ingredient is the sticky substance known as bitumen. This is used to hold the mixture of waste materials together so that they can easily be compacted into a mold to form a solid concrete block. The block is then heat-cured to oxidize the bitumen and make it hard as concrete.
Aside from reducing garbage, making Bitublock produces less CO2 emissions than does making the conventional concrete block.
Bitumen replaces the Portland cement used in manufacturing traditional concrete, which is the source of about 74 to 81 % CO2 emissions in concrete production, which in turn contributes 7% of the global CO2 emissions.
Overall, about 500,000 metric tons of incinerator ash and 400,000 metric tons of crushed glass could be diverted from the dumpsite for making more of the alternative Bitublock.
Concrete made of Fly Ash
Across the ocean, in Austin, Texas, a civil engineering staff professor, Dr. Maria Juenger, proposed to make concrete using the waste material known as fly ash, the by-product of coal-burning industry. “Fly ash is already used in concrete as a cement substitute and has a composition similar to cement.”
Plasma Gasification Process
Another process introduced to squeeze out whatever goodness there is from garbage is the Plasma Gasification Process (PGP), a "thermal process involving the application of intense heat to waste materials in a completely closed, controlled and oxygen-starved environment."
The PGP system has the ability to process any waste stream, including MSW (Municipal Solid Waste), municipal sewage sludge, paint sludge, drum reconditioning sludge, biomedical waste and spent potliner, organic petrochemical sludge, illicit drugs, high metal content waste, coal and MSW incinerator ashes, paper-mill reject waste, fluorescent light ballasts, asbestos-containing material, explosives industry waste, rubber tires and industrial hazardous wastes including PCBs and concentrated insecticides, a granular waste from aluminum smelting, biomass, oil shale, automobile fluff, and lead-contaminated soil.
The PGP as a waste-conversion technology has three by-products, one of which is slag, a glasslike reusable solid that can be molded into bricks. In sand form, it can be mixed with concrete for use in various construction projects.
While these advances in technologies may clearly respond to concerns in proper solid waste disposal management, the question remains whether quarrying can be stopped despite the introduction of potential alternatives.
Quarrying is a part of the big, profitable industrial world manned by powerful corporations, where environmental concerns often take a back seat to economic realities. It may take more than just a simple alternative technology to get rid of it. There is still a long way to go.
Photo: “from whence the brick came” by Len Matthews, c/o Flickr. Some Rights Reserved.
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