Due to the decreasing quality of recycled water, the implementation of a completely wastewater-free production normally fails. In this article, a wastewater treatment plant has turned its dream of realizing zero liquid discharge into reality.
Over the years, freshwater has become increasingly scarce, not only in arid zones but those with sufficient rainfall. This is why years have been spent elaborating concepts for the recycling of industrial rainwater. One challenge is the fact that a reverse osmosis system must be used in most cases to produce the quality required for reuse. However, these same systems produce high salt concentrates, resulting in their disposal expensive and increasingly difficult in large quantities.
Though there have been many descriptions and discussions concerning zero liquid discharge (ZLD) throughout the years, few sites worldwide have been able to implement them with consistency. The reason for this is due to the idea that process-operation needs to be well-balanced and the quality of water must be of a high standard, despite the fact that ZLD systems causes a further concentrate of the substance.
As a result, operations become more difficult and the separate water phase becomes dirtier. Therefore, under continuous operation of such a plant, one has to find the balance between maximal water quality and high concentrations.
Modernising a wastewater treatment plant into a water recycling system
In this context, an initial concept for a water recycling system was designed for an international cosmetics group, which was then further transformed into a ZLD concept via transformation of external site conditions, such as a conventional wastewater treatment plant used for mixed production wastewater had previously been in operation.
However, since it was non-compliant with the discharge requirements of the local industrial zone, Wehrle was contracted to double its plant capacity and upgrade it to a Membrane Bioreactor (MBR), making it future-proof.
The full article is published on the latest edition of Water & Wastewater Asia May/Jun 2021 issue. To continue reading the article, click here.