IWT - INTEGRATED WASTE WATER TREATMENT -
Zero Discharge system for the total recovery of the wastewater produced by the solar cell manufacturing production.
Photovoltaic industry as many other industrial fields is interested by environmental process involving water.
Especially in the manufacturing of silicon multi and mono cell the environmental problem has an impact on the life of the solar cell producers.
The amount of water needed to run the manufacturing process and the discharge of wastewater produced by the wet chemical processes are two important tasks that every producer have to manage.
The IWT is an integrated and closed circuit that works independently from the availability and the quality of the water source available on site, because the IWT system will always work treating and recus the same water.
The two basic principles of the IWT system are:
- To treat and recycle, until it is economically convenient, all water introduced in the system, directly (first charge of ground water to fill the whole circuit and condensed water) and indirectly (acid and alkaline process solutions).
- The IWT system is an integrated and closed-looped circuit that works independently from the quality and the availability of water on site but also it is independent form the discharge limit.
ADVANTAGES of the IWT system:
- IWT operates in every country or condition independently from the quality of the city/ground water and from the discharge limits.
- 97% of water recovery. Once the IWT circuit is topped-up with city water for the first time it will always operates with the same water just with a refill of 5% to 3% of tap or ground water.
- Always ensures stable condition of the input and let IWT provide UPW water at >12MΩ x cm resistivity.
- The disposal of a non toxic solid sludge reduces the costs for the transportation and the off-site disposal.
- Always ensures the ZERO discharge of waste water if needed.
- Uses the minimum quantity of chemicals for the treatment processes.
DIFFERENCES BETWEEN THE IWT AND A TRADITIONAL TREATMENT CONCEPT.
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In the Photovoltaic industry the waste water treatment commonly applied comprehends two different types of water treatement:
- DIW This treatment purifies the Tap Water or Ground water to remove all the salts and contaminant and obtain Ultra Pure Water to feed the tools of the production line.
- WWT Waste water treatment that treates the rinses water proceeding from the production lines.
In the IWT system we have only one Treatment plant in a closed - circuit that recycle the waste water to produce ULTRA PURE WATER. It is a new concept for the Photovoltaic industry because by the IWT system it is possible to recycle also the waste water proceeding from the facilites of the PV factory and the exhausted baths. And the only waste produced is an inhert solid sludge (10-11 tons per MW of cells produced). The system avoids any discharge of waste water respect a Traditional treatment plant that discharges in the public sewage (or in the surface water) and gives to the disposal sludge and the Concetrated Acid Waste flows. The IWT system as it uses always the "same" recycled water reduces drammatically the consumption of fresh water (from the ground or the municipal source) respect a Traditional system that sucks contiunously fresh water. (< 70 mc IWT - > 1800 mc Traditional required to produce 1 MW of solar cells).
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