CAPÍTULO VIII LEGISLACIÓN Y DOCUMENTACIÓN
8.4 Regulación Arancelaria
There is no well-planned legal framework in Thailand for water resource inventory, planning, use, reuse, quality control and protection (Gupta and Babel, 2002). Watercourses are freely available for withdrawal and use. Legislative provisions do not enforce reuse of wastewater. What is practiced on an ad-hoc basis needs to be formalized under set legislative and administrative provisions. Thailand has, over the past 15 years, focused on the management of water pollution with infrastructure for domestic and industrial wastewater treatment systems and the setting up of effluent discharge standards. It is imperative for the environmental agencies to develop appropriate water reuse guidelines and set effluent standards for various reuses to prevent the associated potential environmental and health risks. The increasing demand for water and the limited availability of surface water and over-used ground water has brought about water stress in the country.
The use of wastewater would affect the handlers and consumers of produce (agriculture and aquaculture products) due to crop-contamination and disease linked to water-based pathogens and bioaccumulation of the toxic metals and substances through plants that absorb them from the soil or from wastewater. Therefore, legislation should make stringent effluent standards and guidelines to enable reuse and to protect human and environmental health, to:
• remove or detoxify the contaminants in wastewater and disinfect it;
• modify agri–aquacultural practices (to prohibit irrigation of leafy vegetables with untreated sewage and ensure the use of holding ponds for aquaculture);
• regulate human consumption of certain products; and
• educate handlers and consumers for protective practices.
At the same time, legislation should take into consideration the reduction of fresh water usage and promotion of reclaiming and recycling activities within the framework of industry, by adopting cleaner production strategies with internal and external reuses. PCD has prioritized high water consuming industries for R&D in water use and options for its reduction by encouraging in-plant waste segregation, recycling and reuse. An initial step for waste minimization and reduction of water consumption by as much as 50% is targeted to be achieved.
Legislation and administrative aspects should consider the role of stakeholders in wastewater reuse, basically the following three groups: potential end users, relevant government agencies that monitor the water usages, and the community. A common consensus to identify water reuse possibilities would pave the way for effective management and control of water demand as well as decreasing the pollution load, thus enabling a better control over water quality.
7.5.5 Potentials for Wastewater Reuse
Treated effluent from industries and municipalities can be targeted for several potential uses.
That would significantly decrease or stabilize the freshwater consumption that increases with the population while the available resources are limited. These reuses are:
1. Reuse can be within an industry, by a closed loop water metabolism or recycling by which the industrial units categorize the use of water based on the water quality and the industrial processes concerned. Secondary purposes could be for cooling, boiler feed, surface cleaning, dust suppression, toilet flushing and gardening.
2. Reuse of the effluent from a CETP in an industrial estate/park within it or by another industry within a close range depends upon the quality of water requirement. This internal use has greater potentials. All industrial estates or parks are required by law to make provisions for greenery within its boundary, which are being irrigated to a certain extent by treated effluents. Cooling water for power plants, metal smelting industries, cutting and fabrication units, brick kilns etc. could use treated wastewater.
3. Treated municipal and industrial effluents can be used to recharge the aquifers as excessive withdrawal of ground water has caused land subsidence (up to 10cm/year in BMR) and seawater intrusion (some wells in the coastal zones report up to 3000 mg/L of dissolved solids). Plans are being made in BMR and Samut Prakarn province.
4. In the BMR, effluents are being discharged into canals to replenish the water level that decreases during the dry season and to avoid silting, which also helps recharge aquifers.
5. Municipal effluents could be safely used for street cleaning, watering plants and parks within a city or municipality with adequate transport arrangements rather using canal water for the purpose.
6. Thailand has numerous golf courses which have an average water demand of 1000m3/d and could be the ideal end users of treated effluents.
The primary constraints and reservations for reuse of municipal effluent in parks, golf courses, watering of plants within street premises and street cleaning would be the odor problem, microbial quality and economical transport of reclaimed water.
The use of CETP effluents for secondary purposes within the industrial estates has similar reservations with regard to odor problems and toxic constituents. In addition to the regulation of standards, the cost involved for advanced treatment processes, transport costs (conveyance by pipelines or tankers) need to be attractive and less than the abstraction costs from the ground or centralized supply. Recharge of aquifers would require stringent effluent standards to prevent contamination of good aquifers by toxic substances and dissolved salts for which standard guidance is required.
Technologies can be developed for the reclamation and reuse of building wastewater as in Japan. The treated wastewater can be utilized to flush toilets, irrigating gardens etc. Using biological treatment and membrane separation, sludge generation can be reduced with
methane gas recovery in a compact facility. This reuse is primarily suitable for large commercial complexes, shopping malls, hotels and even institutions.
Desalination
Salinization has become a major concern in the northeast and south of Thailand along the coast caused by saline water intrusion into the aquifers due to excessive groundwater withdrawals, saline water irrigation and expansion of brackish water aquaculture. Areas with scarcity of fresh water would require adopting desalination of the brackish water and seawater in the coastal zones using modern methods like reverse osmosis, which in particular is reliable, consumes less energy, and is easy to operate and maintain. Industries too could adopt the desalination process for obtaining fresh water. Thailand has a desalination capacity of 24,075 m3/d. One such industrial unit is the salination plant operated by Esso Sriracha Refinery, Chonburi.
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©2008 IWA Publishing. Water Reuse - An International Survey of current practice, issues and needs by B. Jiménez et al. ISBN: 9781843390893. Published by IWA Publishing, London, UK.