ASSESSMENT OF WASTEWATER TREATMENT IN DEVELOPING COUNTRIES CURRENT PRACTICES IN VIENTIANE CAPITAL, LAOS

* Minaphone Chanthavilay, Hongtao Wang, Wang Ying and Fengting Li. 1. UNEP-IESD, TONGJI Institute of Environment for Sustainable Development, College of Environmental Science and Engineering, Tongji University, Siping Road 1239, Shanghai 200092, P.R.China. 2. Department of Public Works and Transport, Vientiane Capital, Lao P.D.R. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History


ISSN: 2320-5407
Int. J. Adv. Res. 5(4), 335-344 336 system in place in the city will result in more pollution to the natural water resources. Since there are no separate wastewater pipe network, untreated wastewater from all areas are disposed to the nearby drainage system, as result quite dark color water with a lot of garbage on the surface of water especially in the dry season can be observed in most of the open channels or canals in the urban area. This is very clear indication of deteriorating water environment in the city.

Wastewater Situation in Vientiane Capital:-
Wastewater treatment as part of the sanitation system is an important environmental service that is closely linked to water management. The poor sanitation management in Lao PDR generally contributes to wastewater pollution especially in the urban areas. The major water source for urban supply is surface water since most towns are located along the rivers as groundwater is for the rural population. In Vientiane capital city, current wastewater handling in most urban areas entails on-site disposal system of human waste and black water, either without treatment or with poorly functioning treatment. The increase of pollution and steady decline in drainage water quality is becoming a serious challenge in the management of Vientiane's water resources as it becomes more and more urbanized [4]

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Besides that, Surface water along the urban drainage canals has been deteriorating due mainly to domesticorganic pollutants mostly generated from the daily activities of residents as well as commercial activities. Based on the simulation results, this condition would much worsen in future. Among the urban drainage canals, Hong Chan and Hong Pasak, which receive wastewater discharged from the urban center of Vientiane, have the most seriously deteriorated water quality with BOD concentrations of 30 to 40 mg/l at present. In future, more serious BOD concentrations exceeding 40 mg/l are projected in the entire stretch of the urban drainage system including Hong Ke and Hong Xeng. [5] The growing number of industries has increased the incidence and risk of pollution. The larger mills and industries of concern in Lao PDR are pulp and paper, timber, food processing, garment manufacturing and cement factories and gravel pits [6]. Most of these have only limited wastewater treatment systems for reducing waste concentration sand loads in the final effluent discharge to waterways. A study on wastewater management and building in Vientiane (2004) reported that, with a rapidly growing population in the urban area of Vientiane Capital City, sewerage is becoming a serious problem because of the lack of a sufficient drainage system and lack of sewerage systems, while on-site sewerage disposal or septic tanks are often poorly designed. Further contributing to the problem in urban area is stagnant untreated wastewater from households and some small industries with open roadside drains, flowing directly into marsh or natural channels. This mixing of sewerage in the storm drainage system will continue to have a detrimental impact on public health [7].These are all the significant potential problems that would arise from water pollution among urbanization.

Current wastewater situation in Vientiane city:-Wastewater Generation:-
Approximately 85,000 m3 of wastewater from the urban area is drained to the public waterways every day, only about half of which is treated by the current on-site treatment system such as septic tanks and contributes in reducing the pollution. [8]. Due to natural purification and dilution from existing water channels, ponds and rivers and the limited wastewater load from the current population, the water quality in the natural waterway is still not so severe, only some points during dry season in the water channel can be noticed with dark color.

Sanitation Facility:-
According to the National Statistics in 2005, approximately 90% of households in Vientiane Capital have an access to proper toilet facilities. This shows that sanitary coverage is relatively good, but methods adopted in general for treatment is not satisfactory and maintenance is poor [9] Collection and Treatment:-Currently, there is no separate wastewater collection system in Vientiane City or in other provinces of Lao PDR. Only some sewerage pilot projects had been constructed on a small scale basis by the EU/DANIDA in year  Drainage System:-Urban area of Vientiane Capital is covered by 2 main catchments areas (a) Hong Xeng system consists of Hong Xeng and its tributaries, Hong Kai Keo, (b) Hong Kesystem consists of Hong Ke and its tributaries. These areas are a sub-catchment area of the Mak-Hiao River [11] Wastewater Treatment facilities:-Vientiane has no public wastewater treatment system and sewage has long been naturally treated through the marsh in the region. Moreover, sewage of some buildings is discharged through septic tank, and even existing septic tanks are too deteriorated to That Luang marsh in the east through combined sewer pipe and channel before flowing into Mekong River. Marsh serves the lagoon but the area of marsh in urban area has been deceased and could hardly accommodate the increasing contamination and sewage. Though the large scale That Luang Marsh serves the lagoon, it would be decreased due to growing urbanization.

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Strategy on sanitation and Waste water management in Laos:-Government strategy for waste water system development: The model of waste water treatment system will be apply with appropriated districts criteria that will be onsite (Dry pit, septic tank) or outside treatment with DEWATS or Centralized system. Some districts or cities can be only DEWATS or mixed between DEWATS and Centralized system that depend on each criteria districts/cities .The solution from 2014-2030, the Urban sanitation development strategy will be focused on DEWATS system as a key method for waste water treatment system in both urban and suburban area including rural area [12]. The model of waste water treatment system will be apply with appropriated districts criteria that will be onsite (Dry pit, septic tank) or outside treatment with DEWATS or Centralized system. Some districts or cities can be only DEWATS or mixed between DEWATS and Centralized system that depend on each criteria districts/cities. The solution from 2014-2030, the Urban sanitation development strategy will be focused on DEWATS system as a key method for waste water treatment system in both urban and suburban area including rural area. [13] The Characteristic of DEWATS in Laos:-Decentralized Wastewater Treatment Systems (DEWATS) is a technical approach rather than merely a technology package. DEWATS applications are based on the principle of low-maintenance since the most important parts of the system work without technical energy inputs and cannot be switched off intentionally. State-of-the-art technology is being offered in DEWATS applications at affordable prices since all of the construction materials are being sourced out locally. The major benefit of decentralized wastewater systems is improvement of human health and ecosystem in any area where they are used. This is due to the elimination of illegal discharges into surface rivers and the removal of failing or poring performing soil absorption systems that contaminate the groundwater supply [14]The decentralized wastewater treatment concept will not be the answer to all wastewater management problems. There are many potential benefits of this alternative technology indicate that it is a system which deserves much larger attention, particularly in smaller communities and the developing urban fringe [15]Technologies of DEWATS.
The basic technologies of the DEWATS used in all three of these projects are basically identical, with differences only in treatment capacity. This module of DEWATS used by BORDA-LIRE consists of the following sections, in order of wastewater flow: control boxes, grease trap, primary settling unit, anaerobic baffled reactor, anaerobic filter, and discharge pipe. Control boxes are valves placed at each connection from a toilet /septic tank to the main drainage line. A grease trap is a simple tank, one or two chambers, with influent and effluent pipes positioned fairly deep below the anticipated water level. Since grease (oil) floats on water, influent grease rises to the surface and is trapped there, while the remaining wastewater exits through the sunken effluent pipe. [16] Main DEWATS modules for physical and biological wastewater treatment Case studies of Decentralized Wastewater Treatment Systems (DEWATS) in Vientiane city.

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Case study of decentralized wastewater treatment in Vientiane, Kualuang Temple and Kualoung School and Thongkhankham village. For the first project in Thongkankham Village, the DEWATS was connected to 22 households and 1 noodle-making shop, with approximately 146 total users. As well, 9 of the households also received toilet renovations, which make them the most direct beneficiaries of the project. The improvements made in wastewater management, however, extend beyond the 146 users, and other residents in the Village area will also benefit from the reduction in groundwater pollution, foul odor, and poor drainage. For the second project in Khoualuang Primary School and Temple, there are approximately 116 students and monks who are now covered by the DEWATS. As well, since the project included renovation of the school toilets, the students will now be able to enjoy this additional benefit. The residents of the surrounding area will also benefit from the reduction of foul odor, groundwater pollution, and flooding from these nearby sanitation improvements. The most direct beneficiaries of a less polluted stream, though, will be the residents living along it on its lower banks, who draw water from it for their daily use. The water quality testing carried out upon the completion of each project indicates the efficient nature of the DEWATS design. The three projects, Thongkankham, Khoualuang school and khoualuang temple, had influent BOD and COD values (in milligrams per liter) of 226/485, 87/194 respectively, which do not comply with any national discharging regulations. However, the resulting effluent BOD and COD (in mg/L) after treatment at these three projects was 162/21, 359/49, which comfortably complies with the respective national standards of 200/400, 40/130, and 60/350, respectively, for this projects. These values should continue given proper operation management and indicate that these projects were successful in their objective of treating the wastewater from these communities to reduce groundwater pollution, foul odors, and health risks [17]

Conclusion and Recommendations:-
Based on the current practices and challenges, here we propose the following recommendations for the improvement of water and wastewater treatment in Vientiane capital, Laos. Urbanization in Vientiane has been rapidly progressed, and natural environment in the urban areas has been deteriorated in parallel. The natural environment, however, still significantly remains in Vientiane in remediable level, so that it shall be urgent issues to conserve the remaining natural environment and to restore the lost one. In finalizing this paper, those points and issues are summarized to provide some help in the future improvement of water environment.
1. Early Implementation of the Structural Water Environment Improvement Plan Rapid urbanization in Vientiane has been progressing in a very fast pace. As frequently described, water environment improvement shall consist of the integrated man-made treatment facilities and the natural purification functions of marshes, ponds and river courses as natural assets given to the Vientiane residents from the physical improvement viewpoint. In this regard, the first step of the improvement works shall be started as early as possible, so that the residents can understand the importance of conservation of their precious environment. This process could be easily linked to the enhancement of people's awareness on environmental improvement.

Prevention of Concrete Covering on Drainage Systems
Hong Thong receives wastewater and rainwater from the most congested areas of Vientiane,vsimilar to Hong Pasak. Hong Thong joins Hong KhouaKhao near the NongChanh Marsh, and changes its name to Hong Ke. Hong Thong has been covered with concrete slabs in almost all its stretch. Although the concrete covering is one of the alternatives to make people disregard the offensive odor and deteriorated scenery of worsened water quality, difficulties on the improvement of water environment will come out due to the invisibility of existing conditions of mg/l mg/l mg/l mg/l mg/l water quality and the inability of conducting improvement works as well as monitoring their effects. Conducting possible improvement measures on the water environment in a step-by-stepmanner would rather be recommended than removing the deteriorated environment from theurban residents' vision.

Conservation of Marshes/Wetlands:-
Rapid urbanization, however, has been progressing in/around the That Luang Marsh, so that it isnecessary to conserve the marsh areas and their functions and protect them against theurbanization of Vientiane. Furthermore, the remaining marshes in the urban areas, such as NongChanh, Nong Bo, and NongTha, shall be conserved as well. Unless conservation measures are undertaken, a similar urbanization process, where various wide mashes had existed in the past have been reclaimed into urban areas, would occur in the remaining marshes mentioned above. In order to conserve these remaining marshes and wetlands, the following two conservation approaches are necessary.