Water shortage is one of the major challenges facing the Arab world today. According to the 2009 Arab Human Resources Development report, the UAE and Kuwait lead the rest of the Arab countries in facing severe water stress in terms of the population and the number of available water supplies.
A statement released by the Environment Agency Abu Dhabi said that the country was using up its underground water resources 24 times faster than they can be replenished. If no suitable measures are taken to counteract this situation, the country’s water resources will be totally exhausted in the next 50 years. The use of fresh water should be lowered; in fact, fresh waste should be used only when it is an absolute must.
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However, there are certain guidelines to putting less stress on fresh water supplies, one of them being greywater recycling. Greywater can replace fresh water in many instances, thereby saving money and increasing the water supply in regions where irrigation is needed. In fact, greywater enables a landscape to flourish where water may not otherwise be available to support much plant growth like in arid desert lands.
It’s a shame to irrigate with great quantities of drinking water when plants thrive on used water containing small bits of compost. Loss of nutrients through wastewater disposal in rivers or oceans is a subtle, but highly significant form of erosion. Reclaiming nutrients in greywater helps to maintain the fertility of the land.
Greywater is wastewater that comes from the kitchen, shower, bath, sinks, and laundry. It accounts for 50 to 80 percent of household wastewater and a lot of it can be reused. Apart from landscape irrigation, greywater systems can be used for purposes like toilet flushing as well.
The US Green Building Council is one amongst other organizations which independently chooses greywater standards as the technology with which to launch their programs of regulatory reform. There are eight million greywater systems in the US with 22 million users, yet there has not been one documented case of greywater transmitted illness, which dispels the doubt most skeptics would have towards greywater usage.
However, greywater systems are more context-driven than any other manmade ecological system and more connected to other systems, for e.g. commercial laundries, whether in-house or centralized.
In-house laundries are typically found in hotels, hospitals, nursing homes, prisons, universities, etc, whereas centralized laundries are operated to wash the laundry of other businesses. In either case, both types of facilities use vast amounts of water with the water-saving potential existing in both.
However, whether water recycling or greywater reuse will exist as a water conservation strategy depends on many factors, which will also determine whether greywater will either be treated for other use such as irrigation or reused back in the laundry.
Factors determining the use of greywater
Sreejith Narendran, Division Manager, Professional Laundry Equipment Trading (PLET) at Al Hathboor says: “Where there is an immediate need for irrigation water within the premises, it is better for wastewater to be treated for irrigation purposes rather than recycling within the laundry itself, but if the wastewater from the laundry has to be paid to be bailed-out, recycling becomes feasible.This also applies if the water discharge costs are high, or if the laundry does not have fresh water supply at reasonable rates. Such cases are more in remote locations and labour camps where captive power and tankered sweet water is relied upon.”
Citing economic factors again, Narendran said that the significance of the importance of greywater recycling in terms of saving money for the laundry would depend on the availability of water to the particular laundry and the rate at which it is available. “If the laundry uses washer-extractor systems, the water consumption per unit of clothes washed is above 20 litres/kg and if continuous batch washers are used, the water consumption is below 8 litres/kg. Depending upon the volume of water required in the said plant, water recycling should be opted for.”
However, the cost scenes can be really different for different hotel properties. For properties with the advantage of having municipal water and central sewage, the return on investment need not be as much as it is for a resort hotel with no central sewage.
“As the system involves huge volumes of water to be processed in very less time, the control mechanisms are expensive. We offer online monitoring of the parameters and online diagnosis and intervention, along with Kemco Systems of USA. These are the same for a small-sized system as well as for a fairly large system. If the total water to be recycled is less than 5000 litres/hour, there is less economy compared to larger installations. For a central laundry with consumption of 25 cu.mts/hour and no municipal water or central sewage, payback can be even less than 18 months,” asserted Narendran.
Like other systems, the recycling system is best incorporated in the design stage as it takes ample space, power and proper co-ordination of wet services pipework. However, it can be retro-fitted as well with /upgraded provisions for power and space. It can be integrated to any system with available provisions for space and installed power. “The advantage of having the same in the design stage would be lower costs as a lot of unnecessary elements can be taken out, which will otherwise remain in the network unused when the water recycling is introduced.” However, despite the presence of several technologies for recycling water in the Middle East, “we are yet to see a system that ‘works’,” says Narendran, citing factors such as the high capital investment costs associated with installing the right system working as deterrents.
The recycling process removes lint, minute solids, organics, detergents, surfactants, oil and grease, odor, and other contaminants. Speaking about practical difficulties that often arise in laundry greywater recycling systems, Narendran refers to oil, grease, detergents and other macro-particles as the particles that prove to be difficult to separate. “Most of the troublesome particles are long molecules which are not filtered out and tend to clog the systems. PLET works with Kemco with their (CMF) Ceramic Microfiltration System that efficiently filters out all these particles before the Reverse Osmosis process which delivers the final product.”
With respect to greywater recycling systems within a healthcare laundry setting, the only difference between the healthcare laundry setting and others would be the inclusion of human wastes in the former. “The standards of washing depends upon the regulatory requirements and a proper segregation of the different types of classification (infected and standard) can make it possible to recycle the wastewater from these installations and make it meet any stringent standards,” said Narendran.
With recycling systems, a 100 percent of wastewater can be reclaimed. The only water lost in the process is that which is lost through evaporation, approximately 10 percent of total water usage. A small amount of recycled water is used to backwash the filters periodically. The recycled water is then disinfected and ready to use again for both the hot and cold water supply.
Greywater systems that are above ground level and are discreet in size are a much sought-out options in ‘Green Buildings’.
The most significant factor is that greywater recycling offers consistent water availability to overcome drought and water restrictions. Architects can design sustainable buildings which can still offer residents lush gardens and water features, using water that would otherwise be destined for the sewer.
