Zero Liquid Discharge – One of the most critical crises that the world is facing today is indeed the freshwater crisis. The increase of water usage by both the industrial and commercial sectors has posed a major threat to the quickly replenishing water resources. The increasing population which in turn increases the demand for safe drinking water along with the added development of the industrialization have further complicated the efforts of saving drinkable water. As the number of water users is more, it is obvious that the waste would be more too. Moreover, this coercing situation has compelled the scientists to come up with different wastewater treatment techniques. This is not something that has been recently adopted, however, it has been implemented since decades just like the membrane filtration systems, different wastewater treatment techniques have evolved a lot lately. One of the most effective water strategy out there today is Zero Liquid Discharge (ZLD). It has been a proved method to eliminate waste from water to a much greater extent thereby improving the quality of the water recovered.
When the Zero Liquid Discharge (ZLD) wastewater treatment system was first introduced, it was basically based only on series of thermal processes. The process was quite simple where the wastewater was treated in a brine concentrator and a brine crystallizer and the byproduct would be usable water. However, before passing it through the concentrator and the crystallizer it was first treated with a pretreatment in order to reduce the scaling of the waste particles in the water. The waste from this process was either dumped or used as useable byproducts.
In addition, a quite popular and effective membrane filtration process called reverse osmosis (RO) can be incorporated with the conventional Zero Liquid Discharge system so as to decrease the energy consumption rates. Here, the RO process can be used as pretreatment phase of the feedwater so that it decreases the salinity of the wastewater thereby improving the cost and energy consumption aspects of the ZLD systems. Moreover, along with incorporating RO systems with the ZLD systems, one can also make use of extensive pretreatments in order to reduce the membrane fouling or scaling. Yes, it might add to your operating costs and hence, here you can make use of more than one membrane filtration processes such as ultrafiltration which can act as an effective pretreatment method.
Where the main aim of introducing new wastewater treatment systems is to control the water pollution, here Zero Liquid Discharge can work wonders in balancing the demand and supply of water for industrial plants. Yes, investing into Zero Liquid Discharge system involves high usage of energy and high operation costs, however, ZLD systems can promote water reuse as well as cutbacks on the use of freshwater. It also decreases the amount of toxic waste that is released into the environment thereby protecting the whole ecosystem. As said above, by combining more than one membrane filtration systems, you can use ZLD systems and get productive results in comparison to using ZLD systems as a standalone wastewater treatment system.