Zero Liquid Discharge
Water is the most important natural resource. Demand of water is increasing day by day.
So, recycling of industrial waste water and reusing the effluent is the only way to meet the growing industrial water consumption rate. Rate of waste water recycling is still negligible. In compliance with the increasing social responsibility towards awareness of environmental issues, governments across the globe are adopting new guidelines and moving quickly to put stricter discharge regulation. Production plants will be expected to comply or face heavy penalties.
ZLD, Zero-Liquid-Discharge is a new water treatment system. ZLD is a water treatment process in which all waste water is purified and recycled to be used as feed water to the plant for leaving zero discharge at the end of the treatment cycle. The existence of conventional water treatment systems which produces treatment water as effluent to discharge is no longer enough.
ZLD technology includes pre-treatment and evaporation of the industrial effluent until the dissolved solids precipitate as crystals. These crystals are removed and returned. The water vapor from evaporation is condensed and then returned to the process. Recycled water has become more affordable as the water supply from conventional sources becomes more expensive. A ZLD sector was apparently born in 1970s in USA.
Most refineries need to be ZLD regulated since new guidelines are expected to be effective in 2017 and 2022 on various types of discharges.
For the purposes of saving the cost of raw feed water, high cost of discharge to sewer system, saving chemicals which are used in the treatment of raw water to be able to feed it into the boilers & cooling towers; and also saving treatment chemicals introduced inside boilers & cooling towers systems, AMOC has decided to follow ZLD system.
After studies were undertaken by AMOC specialists and with (EWATEC) consultancy group, it was found that “approach ZLD” (liquid discharge with smaller amounts) is more economic & suitable than ZLD for AMOC. It involves the same technology as ZLD except for the evaporation stage.