Using Water Hyacinth plants to reclaim sewage water

• goh meng seng

  7 Oct 04, 13:53

  I have come across this website on an interesting method of sewage treatment.
  
  It may just prove more cost effective this way.
  
  Goh Meng Seng
  
  http://technology.ssc.nasa.gov/suc_stennis_water.html
  
  Success at Stennis
  
  A New Image for the Water Hyacinth
  In tropical and subtropical areas where water hyacinths grow, including the southern United States, these aquatic plants are generally considered a colossal nuisance. They are extra-ordinarily prolific, virtually indestructible, and their rapid growth clogs rivers and streams.
  
  However, in a small but growing number of American communities, the glossy green, violet-flowered water hyacinth is developing a new image as a useful and beneficial plant. Its upgraded status stemmed from the discovery ?in a NASA technology application project ?that water hyacinths thrive on sewage; they absorb and digest wastewater pollutants, converting sewage effluents to relatively clean water. Thus, the plants have exciting promise as a natural water purification system, which can be established at a fraction of the cost of a conventional sewage treatment facility. Water hyacinths are serving that purpose in several locales and a number of other communities are considering adoption of the technique.
  
  For maximum effectiveness, pollution-gorged water hyacinths must be harvested at intervals, but this apparent drawback offers potential for additional benefit. Harvested plants can be?and are being ? used as fertilizer. They can also be heat-treated to produce consumer energy in the form of methane gas. And if an economical way of drying the plants can be developed, they may find further utility as high-protein animal feed.
  
  NASA launched its initial water hyacinth experiment in 1975 at the National Space Technology Laboratories (NSTL), Bay St. Louis, Mississippi. With the cooperation of Bay St. Louis officials, NSTL
  
  Fenced off seven acres of the city÷Õ 40-acre sewage lagoon and planted water hyacinths. The plants flourished on the sewage and the once-noxious test area became a clean aquatic flower garden.
  
  On the basis of this and other experiments, NSTL described the method and results in a study report which has been widely used as a basis for further application of water hyacinth technology. One of the earliest users was the town of Rio Hondo, Texas, population 2,000. Seeking alternatives to construction of a costly conventional sewage facility, town Mayor Juanita Brodeky learned of NASA÷Õ work, contacted NSTL and obtained literature and personal guidance. Rio Hondo decided to adopt the NASA system, dug lagoons and imported water hyacinths. For more than four years, the plants have proved an effective, year-round means of treating sewage. The initial cost of the facility came to only one-twentieth the quoted estimate for a conventional system.
  
  Similarly, the community of Orange Grove, Mississippi, shelved plans for an expensive mechanical system and opted instead for a combination of wastewater treatment methods in which water hyacinths play a leading role. In Florida, the Coral Springs Improvement district used NSTL÷Õ research as the basis for a 150,000 gallon-a-day water hyacinth pilot plant which has been operating since 1978; installation costs were 40-70 percent below those of a conventional system and ongoing costs run 25 percent less. The city of Lucedale, Mississippi plans a program, which will include water hyacinth treatment of sewage together with methane generation from harvested plants.
  
  Walt Disney World, Lake Buena Vista, Florida, activated a prototype 100,000-gallon-a-day sewage treatment plant using NSTL÷Õ water hyacinth technology. The plant is part of the Experimental Prototype Community of Tomorrow (EPCOT), being created to provide a site for demonstration of new technological, social and aritistic concepts. Among the sponsoring organizations of this project-along with the Environmental Protection Agency, the Department of Energy, NASA and private companies is the state of Florida, which is studying the possibility of using water hyacinth technology on a statewide scale. Florida has a need for improvement of its rural sewage treatment procedures, and it is estimated that water hyacinth systems could halve the $330 million cost projected for upgrading the state÷Õ sewage facilities by conventional means.
  
  The city of Hercules, Georgia, has built a 350,000-gallon-per-day water hyacinth wastewater treatment plant. The unique facility has a greenhouse cover, which permits year-round operation. It can be expanded to treat almost two million gallons of raw sewage wastewater daily.
  
  The largest application of water hyacinths yet initiated is a million-gallon-a-day pilot plant recently approved for the San Diego (California) Water Utilities Department (SDWUD), which handles sewage treatment for more than two million area residents. SDWUD contemplates a recycling system in which water hyacinths, combined with a mechanical system for separating solid waste, will restore wastewater to a certain level of purity; further treatment by other means would make the water pure enough for drinking and general use. Interested in broader application of water hyacinth technology, the California Water Resources Control Board has established an Aquaculture Studies Section to investigate the matter.
  
  A number of other state and local governments are looking into water hyacinth sewage treatment and there are also several experiments under way to explore the plant÷Õ byproduct potential as a source of methane gas or animal feed. For example, United Gas Pipe Line Company is one of the sponsors of the Disney World EPCOT program; in addition to its EPCOT study of separating methane from heat-treated water hyacinths, the company has been considering construction of a pilot plant in Louisiana to investigate large-scale production of methane from a combination of water hyacinths. Bermuda grass and municipal sewage.
  
  Using harvested water hyacinths as animal feed was researched by the Louisiana State University Agricultural Experiment Station. In one test, conducted with NSTL cooperation, researchers fed chopped, solar-dried water hyacinths to a herd of dairy cows for four weeks; it was found that the cows produced as much milk-and of comparable qualify-as did cows fed their customary hay ration. LSU dairy scientists feel that the plants could become an alternative livestock feed when land now used to grow forage may have to be used to produce food for humans.
  
  Additional research is needed before water hyacinths become practical, economical sources of methane or animal feed, but the plants have already demonstrated their efficacy in sewage treatment and wider application for that purpose seems likely.
  
• goh meng seng

  7 Oct 04, 14:16

  I think it brings about the Wastewater Gardens:
  
  http://www.idepfoundation.org/default_site/wwg2.htm
  
  Partnering with PCRF – IDEP brings Wastewater Gardens® Technology to Bali & Indonesia
  In 2002 Yayasan IDEP established an MOU with PCRF (The Planetary Coral Reef Foundation), to introduce one of the worldÂ’s most effective technologies for environmentally sound wastewater treatment. PCRF has over a decade of research in the use of constructed wetlands for wastewater treatment.
  
  The system was developed as part of the Biosphere 2 closed ecological system in Arizona (1991-4). In the years since, PCRF has created Wastewater Gardens® in the US, Europe, Mexico, the Bahamas Belize, Indonesia & Australia, see www.pcrf.org Wastewater Gardens® are sealed subsurface flow wetlands that use plants, microbes, sunlight & gravity to transform wastewater into beautiful gardens & reusable water.
  
  The technology has been reviewed by the U.S. EPA & European Health authorities, and meets their wastewater standards. This system has been proven to be far more effective, affordable & long-lasting than conventional sewage treatment systems, particularly in tropical zones.
  
  Currently there are eleven Wastewater Gardens® in Indonesia, all of which have been designed and installed by members of the IDEP team. This includes systems we have made for residences, hotels/resorts and a local school (Sunrise school). We are currently developing a new system for a community and their new education center in Sulawesi with MAP-Mangrove Action Project (see links page) to protect their critically threatened mangrove and reef habitats.
  
  Yayasan IDEP is working to increase the awareness of the Indonesian public and local government with regards to the system and its applicability as a sound solution for addressing the increasing need for available fresh water nationwide.
  
  Why choose Wastewater Gardens®?
  Introduction:
  Current Problems with Sewage Treatment
  Pollution of water resources by improperly or inadequately treated domestic wastewater (sewage) contaminates drinking water supplies and so is a leading cause of human disease worldwide.
  
  Health problems related to sewage are widespread, ranging from children swimming in open sewage treatment ponds, failure of leach fields due to wet season inundation, and sewage effluent pollution of groundwater, rivers and lakes with adverse impact on drinking water quality and recreational use of these resources.
  
  Small, rural and isolated communities often canÂ’t afford the great expense and difficulty in maintaining highly technical wastewater treatment systems. It is frequently reported that maintenance in such situations soon becomes almost non-existent and inadequate sewage treatment results.
  
  In addition to issues of human health, the release of nutrients from this wastewater causes eutrophication in the environment, leading to a wide range of environmental problems. These include:
  
  Mangrove habitat & Coral reef decline
  Oxygen depletion
  Marine life/ Fish mortality
  Ecological degradation of rivers and lakes
  Giving competitive advantage to weed species over native plants.
  Constructed Wetlands as an Alternative Method of Wastewater Recycling and Treatment
  The past several decades has also produced new discoveries to solve this situation, stemming from a fundamental change of perspective based on a total ecosystem approach.
  
  “Wastewater” is in fact a valuable source of nutrients and water, upon which ecologically flourishing wetlands can exist. Wetland scientists have demonstrated that not only natural but also properly designed and constructed man-made wetland ecosystems are extremely efficient at utilizing and cleaning such nutrient-rich waters.
  
  The new disciplines of “ecological engineering” and ecotechnics seek to utilize predominately natural, ecological mechanisms to integrate the human economy and technology with the biospheric ecology.
  
  This approach turns what was previously “waste” into green plants and reusable water. Wetland ecosystems can be constructed for less cost, because there is less reliance on complex technology which is capital and maintenance-intensive, and which uses electricity / fuel.
  
  The use of ecologically constructed wetlands for human sewage treatment relies on the ability of green plants and non-pathogenic microbes rather than expensive machinery.
  
  In addition, designed wetlands create a “buffer” ecosystem between the human economy and the environment to mitigate negative impacts, illegal as well as unpleasant and unhealthy.
  
  Wastewater Gardens® systems are less expensive to build than conventional sewage treatment and running costs are dramatically lower (5-10% of ordinary maintenance and operating costs), since little or no machinery is used ,and gardening skills are the primary need once the system is operating. Many systems can be designed to rely completely on gravity-flow eliminating the need for pumps and electricity.
  Wastewater Gardens® become more effective at wastewater treatment as the plants establish, compared with mechanical systems which become less effective as machinery ages. Subsurface wetland systems are long-term solutions. They have continued to function for decades since their original development in the United States and Europe in the 1970s.
  How it Works-the techology:
  Wastewater Gardens® is an ECOTECHNICS invention that uses very effective, ecologically sound, design principles.
  
  Primary treatment of your sewage water, to separate solids, occurs in a conventional, watertight septic tank or settling lagoon. Then, instead of passing directly into a leachfield (with its attendant problems of little further treatment, smell, clogging and large size), the nutrient-rich wastewater effluent passes into a water-tight treatment compartment that is single or multiple-cell depending on system size.
  
  The treatment compartment is then filled with gravel so that the wastewater is kept just below the gravel surface. Into this gravel, a wide variety of wetland plants, specially selected for the locality are planted.
  
  As entering effluent overflows from the first stage cell, where the primary treatment occurs, it passes to the second cell, where advanced treatment occurs, and then into a comparatively small subsurface discharge cell.
  
  The treated water can be recycled for further irrigation of lawns, shrubs, flowers or trees. Wastewater is generally held in the wetland systems for 5-7 days.
  
  Why it works:
  Wastewater Gardens® use plants, microbes, sunlight & gravity to transform wastewater into beautiful gardens & reusable water. The technology has been reviewed by the U.S. EPA & European Health authorities, and meets their wastewater treatment standards.
  
  The design uses only one fifth the area of open wetlands & its high bio-diversity raises constructed wetlands to a complete ecological system.
  
  THE ADVANTAGES:
  of the ecological subsurface flow wetland approach include:
  Fecal coli form bacteria are reduced more than 99% in the wetlands, without the use of expensive, environmentally harmful chemicals like chlorine.
  Biochemical oxygen demand (BOD) reduced 85-90% from influent levels, and removal of nitrogen and phosphorus is substantial.
  The wetlands are low-cost, low-tech and long-lived. Maintenance requirements are simple.
  There is no malodor as the sewage is kept from contact with the air.
  There are no mosquito-breeding or other nuisances associated with open wastewater (e.g. sewage lagoons or surface-flow wetlands).
  The possibility of accidental public contact with the sewage reduced to someone deliberately digging into the wetland gravel.
  Subsurface flow wetland systems are capable of extremely high rates of wastewater cleaning. In research over the past several decades, this type of wetland, even in its earlier design forms, has a well-documented track record of consistently cleaning water to levels better than municipal standards for wastewater treatment.
  The intensity of treatment is such that only 1/5 the area is required compared to a surface-flow wetland. Every particle of gravel becomes colonized by the natural variety of microbes that are effective in utilizing and treating wastewater, and the root systems and water/nutrient uptake of the plants increase treatment efficiency.
  Where higher treatment than normal municipal standards is required for special purposes, an increase in wetland area provides the equivalent of advanced water treatment.
  Significantly less wastewater (35-70% depending on design) is discharged from these special wetlands, because the plants use large quantities of water in their transpiration.
  Subsurface wetlands can be exactly sized from small units for a single residence to larger areas for small city/town systems and so no surplus capacity need be paid for than is needed. On the other hand, new demands can easily be met by simple unit expansion
  The wetland systems add considerably to the landscape beauty in communities where they are used, and can also include plants to be harvested for useful or saleable products. In Mexico and Bali, hotels and house-owners with wetland treatment systems are now competing for the most beautiful gardens!
  Wastewater Gardens Save You Money:
  Wastewater Gardens® systems are less expensive to build than conventional sewage treatment and running costs are dramatically lower (5-10% of ordinary maintenance and operating costs), because:
  little or no machinery is used and systems can be designed to rely completely on gravity-flow, which removes the costs of:
  Pumps
  Electricity
  Replacement of parts/ technician labor / yr
  they are natural systems, which removes the costs of:
  expensive chemical additives /mth /yr
  and Wastewater Gardens® become more effective at wastewater treatment as the plants establish, unlike mechanical systems which become less effective as machinery ages,
  In addition, Wastewater Gardens®offer the following advantages over conventional treatment:
  no odour
  additional landscape beauty
  higher water quality treatment
  more reliable performance (20yrs+)
  insurance against inflation increasing maintenance costs (parts, electricity, chemicals)
  Wastewater Gardens® have proven to be far more effective, affordable & long-lasting than conventional (high tech) sewage treatment, particularly in tropical zones.
  
  Applicability in Tropical Conditions:
  
  Since these systems rely on green plants and microbes, they perform even better in warm, sunny conditions than the successful wetland systems in cold climates such as Canada, Germany, the United Kingdom, and northern United States. In milder and especially tropical conditions with higher temperatures and increased sunlight, system effectiveness is high year-round. Thus, the approach seems ideal for tropical areas, remote communities, rural towns and houses.
  
  Wastewater Gardens® are especially recommended for use in on-site systems for houses in areas with groundwater close to the surface (such as often occurs during the wet season) and for sites with rocky or impermeable clay soils that prevent standard leachfields from operating.
  
  RESEARCH
  Background
  Wastewater Gardens® were used in the world’s first laboratory for global ecology, Biosphere 2, a 3.15 acre materially closed facility near Tucson, Arizona. Dr. Nelson, one of the pioneers of Wastewater Gardens® , was a member of the eight person “biospherian” crew for the first two year closure experiment, in 1991-1993. During this period, in the enclosed systems Dr. Nelson was in charge of the wetland wastewater treatment system which treated all domestic sewage from the internal crew, plus wastewater from laboratories, workshops, laundry and domestic animals.
  
  Wastewater Gardens® advanced design, raises artificial wetlands to a complete system that has been extensively tested and successfully applied over the past several decades in over three hundred sites worldwide.This basic approach has been extensively tested and successfully applied in the United States and Europe over the past several decades.
  
  This advanced design, which raises artificial wetlands to a complete system, is now operating in over fifty sites in southern Mexico, Belize, Bali, Indonesia, the United States and Australia.
  
  In Mexico:
  Detailed research was conducted for the Wastewater Gardens® systems constructed along the coast of the Yucatan, in southeastern Mexico, and the results critically checked by University of Florida scientists:
  
  These Wastewater Gardens® systems prevented pollution damage to off-shore coral reefs, using 3-4 square meters of wetland per full-time resident. This ratio proved capable of reducing BOD (a measure of organic compounds in water by 85-90%, significantly reducing nitrogen and phosphorus, and reducing fecal coliform bacteria by around 99 % without the use of expensive and environmentally-harmful chlorine.
  
  Two Wastewater Gardens® systems totaling 130 square meters, treated the grey and blackwater of 40 residents. The systems supported 65-70 varieties of wetland plants, with biodiversity three times greater than in adjoining natural mangrove wetlands, and only 5% less than inland tropical forest areas.The owners have expressed great satisfaction with the quality of the water effluent, the beauty of the Wastewater Gardens®, and the simplicity of maintenance.
  
  How we work with you to create your Wastewater Gardens®
  1.Initial consultation to determine whether a Wastewater Gardens® system is suitable for them. We will review site and building location plans and discuss possibilities for location of the septic tank and Wastewater Gardens® system.
  
  2.Initial site visit with client to review land contours, existing trees, drainage areas and other factors that will affect the placement and functioning of the Wastewater Gardens®. Shapes for the gardens will be discussed at this time as well as types and varieties of plants suitable to the project and owner's taste.
  
  3.Meeting with client and contractor to hand over and discuss the designs and plans for their Wastewater Gardens®. If this meeting occurs at the construction site, then the area for the Wastewater Gardens® can be staked out at the same time.
  
  4.Inspection. If the project is large and/or requires steel reinforcement we will inspect the Wastewater Gardens® when it is framed and has piping in place, before the cement is poured. For smaller projects we inspect the Wastewater Gardens® after piping is in place to make sure the levels, and positions are correct.
  
  5.After the cement is poured and/or the walls have been plastered we will supervise a water leak test for the systems.
  
  6.Before gravel is placed in the systems we will visit the site to assure that the gravel is cleaned properly and suitably placed in the Wastewater Gardens®.
  
  7.Planting & final training. Depending upon what option you choose, either we will plant the Wastewater Gardens® or conduct a site visit to supervise the planting according to the design and plan. A list of suitable species is available upon request.
  
  At this time we also hand over the system Maintenance Manual, and teach the staff in charge of maintenance the few simple procedures of how to operate and maintain the Wastewater Gardens®. Follow up visits are available upon request...
  
  Wastewater Gardens® for the home:
  To date, Wastewater Gardens® have been installed in over 250 homes & residences worldwide. Including Wastewater Gardens as part of your home is the most economical, ecologically sound way of reducing fresh water contamination in your environment.
  
  What Wastewater Gardens® owners say:
  “What a wonderful thing to take waste and turn it into a thing of beauty." Vince Welnick, Home owner, Akurnal, Mexico
  
  Wastewater Gardens® has proven to be the most cost effective and maintenance friendly system for the complete treatment of household wastewater in the US, Europe, Mexico, Bahamas, Belize, Indonesia & Australia. Wastewater Gardens® are beautiful personalized aesthetic statements.
  
  "The Wastewater Gardens® that we had installed is not only a visual enhancement, but knowing what a benefit to our earth it is, makes it so much more enjoyable - truly the best improvement we’ve made to our home." Laurie Welnick, Home owner, Akurnal, Mexico
  
  Wastewater Gardens® for the hoteliers:
  Wastewater Gardens® offers hoteliers an economical, practical low maintenance, and sure-safe solution to their waste water treatment. With Wastewater Gardens® you can preserve and recycle your area’s precious natural resources, while enhancing the beauty of your resort or hotel’s surroundings. Hoteliers worldwide understand that the proper treatment of their business’s wastewater means they can promote themselves as an establishment that is making sound environmental choices.
  
  A Selection of Commercial Wastewater Gardens® Clients: • Sacred Mountain Sanctuary, 12 Luxury Villas use 7 small gardens Located in : Central Bali, Indonesia
  
  "Since we have been using the Wastewater Gardens® system we have not experienced any odor and our guests all love it. I am happy about the aesthetic; instead of a machine that makes noise, requires maintenance, breaks down, I have a beautiful garden. I am thrilled about this beautiful way of treating wastewater." Laura Bush Owner Hotel Club Akumal Caribe Villas Maya
  
  Wastewater Gardens® for the Community:
  As solutions for fresh water conservation become increasingly important to our governments and local communities, Wastewater Gardenss® are being installed into schools, and as community scale treatment systems.
  
  Wastewater Gardens® are an excellent way to increase public awareness about economical solutions to resource management that preserve our health and well-being and that of our environment.
  
  Wastewater Gardens® owners have expressed great satisfaction with the quality of the water effluent, the beauty of the Wastewater Gardens®, and the simplicity of maintenance of the system.
  
  These projects include Sunrise School,Bali; a community in Sulawesi (funded with help from MAP, by CIDA / Seacology), and an aboriginal community in Northern Australia that was government sponsored.
  
  Who is involved:
  Dr. Mark Nelson Phd -
  Dr. Mark Nelson, working in collaboration with the Planetary Coral Reef Foundation (U.S. and Mexico) and the eminent systems ecologist, Prof. H.T. Odum of the internationally known Center for Wetlands at the University of Florida, has developed an innovative approach to wastewater treatment using man-made wetlands, employing subsurface flow.
  
  Dr. Nelson holds a M.S. in Watershed Management from the School of Renewable Natural Resources of the University of Arizona, where his thesis concerned design of zero discharge sewage treatment systems using fast-growing trees. His Ph.D. in Environmental Engineering Sciences is from the University of Florida, where he was a Research Associate with the Center for Wetlands.
  
  Dr Mark Nelson, Ph.D., is Chairman of the Institute of Ecotechnics, Vice President for Wetland Treatment Systems for Planetary Coral Reef Foundation, and a director of the Kimberley of West Australia Savannah Systems P/L project at Birdwood Downs, near Derby, since 1978.
  
  He was a member of the 8-person closure team in Biosphere 2, 1991-1993, where he managed the constructed wetland used for wastewater treatment in the facility. He completed his doctorate in Environmental Engineering at the University of Florida, with a dissertation on subsurface flow wetlands in tropical, coastal environments.
  
  Mark has worked for several decades in closed ecological system research, ecological engineering, the restoration of damaged ecosystems, desert agriculture and orchardry and wastewater recycling.
  
  Dr Nelson is:
  
  • Founding director of the Institute of Ecotechnics
  
  • Chairman and CEO of the Institute of Ecotechnics
  
  • Vice Chairman of Global Ecotechnics Corp.
  
  • Vice-President for Wastewater Recycling Ecosystems for the Biosphere Foundation.
  
  • Director of Space and Environmental Applications for Space Biospheres Ventures He was a summa cum laude graduate from Dartmouth, Phi Beta Kappa and is a member of Phi Kappa Phi, the honors engineering society.
  
  He was awarded the Yuri Gagarin Jubilee Medal, 1993, awarded for outstanding service to international cooperation in space and the environment by the Russian Cosmonautics Federation; and elected a Fellow of the Explorers Club in 1994.
  
  Yayasan IDEP
  IDEP promotes the use of Wastewater Gardens® for application throughout Indonesia. To date several successful models have been established on the island of Bali. Yayasan IDEP is building Indonesian public and Government awareness about Wastewater Gardens® and plans to expand their installation nationwide in both inland and coastal areas.
  
  The Planetary Coral Reef Foundation (PCRF)
  PCRF was founded in 1991 to address the worldwide demise of coral reefs through scientific research and education. PCRF's mission is:
  
  · To establish a global database and baseline for coral reefs.
  
  · To track the health of coral reefs worldwide.
  
  · To pioneer new techniques for monitoring & mapping coral reefs using underwater observations & satellite imagery.
  
  · To develop new technologies for wastewater recycling.
  
  · To improve the technology for restoration of coral reef ecosystems.
  
  · To provide seamanship and coral reef educational opportunities aboard the RV Heraclitus.
  
  · To pursue the research of coral reef pharmaceutical for new medicines.
  
  · To launch international educational campaigns about coral reefs encouraging efforts to preserve & protect them.
  
  To fulfill its mission, PCRF also chartered the 84' research vessel, the RV Heraclitus to conduct on-site studies of reefs worldwide, to pioneer a means to map a living coral reef of Earth and monitor the health and vitality of reefs as an ongoing planetary study using remote sensing and satellite technology.
  
  To date, the RV Heraclitus is the only ship continually out in the field studying and monitoring coral reefs on a planetary basis. PCRF has successfully installed Wastewater Gardens® in Mexico, Bali, the US and Australia.
  
  To date, the largest Wastewater Gardens installed by PCRF is located in the Xpu-Ha EcoPark near Akumal Mexico which handles the effluent produced by up to 1500 visitors a day. PCRF is building public awareness about Wastewater Gardens and plans to expand their installation worldwide in both inland and coastal areas.
  
  PCRF is also engaged in a joint venture to build Demonstration Wastewater Gardenss in three LA schools over the course of the next year. For more detailed information about PCRF www.pcrf.org see links page
  
  
• paperchicken

  7 Oct 04, 16:36

  Speakers Corner is getting water-logged with all the water topics.
  
  Keep similar topics under one thread lah.
• goh meng seng

  7 Oct 04, 16:39

  Dear Paperchicken,
  
  Sorry about that.
  
  You asked a question, I answered in many ways. Now, I need to take another breather
  
  Goh Meng Seng
  
  

  Originally posted by paperchicken:

  Speakers Corner is getting water-logged with all the water topics.
  
  Keep similar topics under one thread lah.

• paperchicken

  7 Oct 04, 16:46

  I am not 100% sure about this but I think PUB use bacteria to break down waste in sewage. Air is pump into water to speed up the process.
  
  Water hyacinth may be a good idea but it may not be suitable in land scarce Singapore because they need space to grow.
• sgsentinel

  13 Oct 04, 16:05

  If its such a good idea PUB would have used it long ago.
• raihanraihan

  13 Oct 04, 20:07

  Mr Goh
  
  Dat's an interesting article.
  
  I always believe that nature is full of wonders, only we are unable to utilise them enough.