Crisis? What crisis? Water shortages in Gauteng have been looming for years, and even when additional water is finally sourced from the Lesotho Highlands through current infrastructure projects, the long-term disparity between supply and demand will persist. One of the biggest problems in my opinion has been that despite sharp increases in water prices in recent years, water supplied to industrial users in Gauteng, and indeed across our semi-arid country, is still not expensive enough. I expect that to change significantly going forward.
In the long term we need to raise the profile of water conservation in all economic sectors. We also need to educate water users about the nature of water as a shared resource, which implies not only that we consider other users and use it as sparingly as possible, but also that we pay attention to the manner in which we use water. Water that is used consumptively is not immediately returned to the resource, and does not become available to other water users. This is the water that is incorporated into products, used to prepare process aids without generating an effluent or is evaporated during the manufacturing process. Excessive consumptive water use drains a catchment of available water. The water that is returned (so-called “return flows”) must be evaluated in terms of its quality. Poor quality return flows may make this water unusable to those downstream, or force them to use water of poor quality, with consequences in terms of economics, health and the environment. This is of particular importance in South Africa, where many vulnerable communities draw water directly from rivers, dams and groundwater without further treatment. While we do have standards for effluent quality in South Africa, the capacity to monitor and police water quality is limited, and it really is up to industry to be responsible in this regard.
So in the long-term, our significant water challenges remain. But what can industry do right now, given the dire situation we find ourselves in? Even if the rains do come in the next few weeks and rescue this season, we will no doubt face this situation again sometime soon. The following are a few basic actions that can be taken:
- Raise awareness among all employees. Because the scale of water use in a factory tends to be high, a running tap or a pipe leak may not seem like a big deal. Make it clear that it is.
- Install water-efficient plumbing. Toilets, taps and showerheads are easy to replace and can yield not only water savings, but energy savings too. In fact, for showerheads the financial impacts of the energy savings exceed those of the water savings. For toilets, a practical low-cost option if you do not have dual flush toilets is the old “brick in the cistern” trick, or a variant thereof.
- Critically examine every process at which water is used and ask how it can be made to use less. Reducing water use at the point of use is the first prize. This does not mean simply closing the valve supplying water to a process – clearly process objectives still need to be met. In many cases however, we use water wastefully – an example would be an unnecessarily high cleaning frequency for a pipeline or vessel. Or an inefficient cleaning process that requires excessive amounts of water.
- Recycle as much water as possible. Water can often be recycled without treatment. Often the key here is to keep clean and dirty effluents from individual processes separate, so that instead of ending up with one contaminated effluent stream, the “clean” effluent can be reused.
- Reduce evaporation rates as far as possible. Evaporation is a consumptive use, and is also energy-intensive. This may require a broader look at your processes, so that the feed to processes involving evaporation is more concentrated to begin with.
- Avoid overflows – this is very common problem in factories we assess. The main culprits tend to be cooling towers and boiler feed water tanks / hot wells. Any vessel with an overflow pipe is a potential problem area. If the overflow is piped into a drain, the problem is often not even evident, so it is a good idea to remove drain covers for a period to identify problem areas.
- If you have a steam system, minimise steam and condensate leaks, reduce flash steam by operating at as low a user pressure as possible and recover as much condensate as possible.
- Excessive cooling tower and boiler blowdown should be avoided.
- Manage effluent quality. In most instances, poor quality effluent highlights resource efficiency problems in other areas, primarily the area of material usage. Dealing with these problems at the source saves materials and improves effluent quality at the same time. Where you have a treatment plant installed, ensure that it is working optimally. Problems in these areas are often very simple to solve and generally maintenance-related.
The above are really only a starting point. A comprehensive water balance is a must, and can be quite easily compiled even where sub-metering is not in place. It may not be 100% accurate, but some information is always better than none. High-leverage opportunities are also typically process specific, and can only be identified through a detailed assessment.
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