There is a revolution underway in the Middle East water sector. Treated effluent re-use is rapdily becoming a serious water resource, and the UAE and Jordan are ahead of the game. “Markets are dramatically growing for wastewater treatment. Initially the wave of water treatment was desalination, but the wave coming up behind it is re-use – and that wave will be larger,” Hu Flemming, Global MD of US consultant Hatch Water and representative of the IPWA told me. “Given the region’s water requirements desalinations alone doesn’t get there. Water management plans have to involve a number of activities and re-use of wastewater that has gone through tertiary treatment is a lower cost option than desalination,” he says.
Some states such as Abu Dhabi are going as far as incorporating the requirement for all effluent to be re-used in their management plans. “Some cities for example are looking at 100 per cent re-use. If there is an excess of TSE this should be scrutinised. An excess means it is not being fully utilised,” Dr Martin Currie, leader of UK consultant Atkins Middle East Water Group explains.
That the use of TSE is a more sustainable solution than desalinated water is generally true, however the re-use of water can present its own challenges, which must be considered carefully. For example a common application for TSE in the region is for use in district cooling systems. Heat is rejected from the chilled water loop by evaporating the TSE, and ultimately a TSE residue is left over. The content of this residue clearly depends on how the TSE was treated beforehand, but as sewage is not normally desalinated, it is likely to contain salt. “Blow down water left at the end of district cooling is concentrated TSE. Where can you put it?,” says Dr Currie.
“The most logical place is in the sewer but some Municipalities won’t allow that due to the high salt levels in the residue, and if everyone did this Municipalities would struggle,” he says. “TSE-fed district cooling plants can use reverse osmosis (RO) to polish the TSE prior to use. While this leads to more efficient district cooling plant, the reject stream from the RO is the very same concentrated TSE that requires disposal.”
One alternative to the sewer would be to put the saline reject stream in the storm water drains. However, as the residue also contains concentrated nutrients from the TSE, this is not an environmentally acceptable route without complex and expensive additional treatment.
Such challenges must be solved as the industry embraces the use of TSE and private sector firms are increasingly working with regional governments on managing and constructing the infrastructure. MEED estimates that there are more than $20bn projects in the wastewater pipeline from PPP in Egypt to maintenance contracts in Saudi Arabia.
For more on wastewater in the region read the full report at MEED: http://www.meed.com/supplements/2010/middle-east-wastewater/wastewater-sector-enters-a-golden-era-in-the-middle-east/3080141.article