Artisans Angkor has worked on an innovative waste water treatment system to reduce its ecological footprint. This new system was implemented at the Angkor Silk Farm site near Siem Reap, and is fully operational. It is a forward-thinking project in a Cambodia.
This new waste water treatment system works by “phytoremediation” which treats environmental issues by ‘restoring the balance through the use of plants’. Phytoremediation refers to the ability of certain plants to bioaccumulate, degrade or render harmless the waste water to be treated.
Thanks to this natural water treatment system, no chemical is used to clean waste water. The latter can then be reused for watering the mulberry trees feeding silkworms or even for the silk dyeing process… The remaining treated water can be naturally poured in the surrounding areas without any harm to nature.
The system also proves to be environment-friendly during its maintenance phase. Indeed, maintaining the system mainly consists in gardening, which will be ensured by two experienced gardeners who had received almost 1-year long training on that matter. Besides, its extreme low electrical consumption makes it an energy saver, which is also beneficial to the environment.
Water Treatment Station was started building on May, 09th 2013 and successfully finished on April, 28th 2014 by DGS Consultants Ltd. The water is tested every one time a year and the testing results are compliant to environment by Ministry of Industry and handicraft, ILCC.
This system collects waste waters from 3 different sources from the Silk Farm with a secured underground pipes network:
- Waste water from the Washing Silk
- Waste water from the Silk Dyeing
- Waste Water from the Ikat Dyeing
From the entry point, the waste waters will start going through several treatment steps and processes. The journey, mainly depending on the weather conditions, will take between 6 to 8 weeks until the waters will come to the lagoon basin.
- First step : anaerobic mixing process
This tank is called the “anaerobic mixing tank” which is underground volume of 150 m3 with the concrete structure. The waters in this huge tank, will slowly run along 3 compartments and will modify its chemical structure, to take a short cut, following the principle of a sceptic tank. The hot waters will encourage the rapid development of specific bacteria. Very quickly, those bacteria will be deprived from any source of oxygen, forcing them to survive in a hostile environment. They will desperately try to find oxygen within the stored waters, striving to eat and decompose materials and chemicals and modifying at the same time their structures. The waters are expected to stay in this tank between 14 days and 21 days. After that time, the overflow will drive the waters into the second step.
- Second step : aerobic process
Unlike the first step, this second aims at considerably reducing the odors by providing 24h a day, 7 days a week, a massive air input. This process, simultaneously, targets to fracture the sulfur and intense reduction of surviving bacteria. This process can take up to a week. This is one of 2 processes which required electrical assistance to pump the air into the tank. All the station uses the gravity in order to ensure a regulated water flow from a step to another.
- Third step : The Horizontal Filters
The water coming to this filter has been already strongly modified since it has first enter the station. There still could be some remaining light smells, depending on the weather condition and the colour can still be not clear. The very first plants are striving to grow in such condition, the further goes along the filter, the better the plants appreciate such an environment. Those filters can then treat, after the biological treatment of step 1 and 2, the remaining metals and chemicals and cope with potential rain waters. The waters will run under the surface in different natural material of different sizes. The plants will use their deep roots to find their needs to grow.
The hydraulic stay in those first filters is around a week all the most. The various conditions of redox, the diversity of this natural environment permits to treat all organic or metallic residues.
After the slow drain through the bottom of those filters, the water will be collected in an open tank with the second point of electrical assistance: an automatic condensate pump which will push the already clear water onto the vertical filters.
- Fourth step : The Vertical Filters
At this step, the water is already clear. This new step in filtration aims at fixing the few remaining suspended elements and finish to oxidize the few rare remaining pollutants. Here the plants grow very fast, extremely fast. The duration of the stay in this filter is really quick comparing to other steps. This duration is guaranteed by the underground pipe system which ensures a minimum water level in the filters. Once the filtration is finished, the completely clear water overflow from this little tank into the lagoon basin.
- Fifth step : Lagoon Basin
The treated water comes into the finishing basin, or lagoon basin. This basin is artificial and fitted with an impermeable lining. It can be used for lagoon but also as a mere decoration. Lagoon permits to give an extra natural treatment which is actually not needed. The natural day light ensures the clotting and settling of what could be remaining extremely light pollutants. The plants is this basin, as the frogs, the fishes, are only here for decoration and … the meal of some of our staff.
There is an overflow at the end of the basin to reject the treated water, compliant with the Environmental laws which, in the 4 years, has been used. The water station, as being an innovative project, have taken into account the risk of an experimentation and is running with a calculated and chronicle water deficit.