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Disinfection Byproducts (DBPs) & Health Risks

Global Water Resources

Only 2.5% of the over 1000 million cubic kilometers of water on earth is available as freshwater. However, only one third of the remaining is available to humans for use. Within the last five decades, total water withdrawal for human uses had almost tripled. Based on current projections, global water consumption will increase to over 5000 km3/year by 2025. By 2030, about 62% of the world population has been projected to experience water scarcity.

Total Water Management in arid regions

In most arid cities of the world, the implementation of an effective water management system requires the use of reclaimed wastewater for non-potable public uses. Undoubtedly, there is enormous reliance on energy intensive seawater desalination technologies to meet fresh water demands in these cities. In Abu Dhabi, United Arab Emirates (UAE), the significance of the use of recycled water in support of the emirate’s sustainable development goals cannot be overstressed.

Water demand in the Emirate has also been projected to grow by 43% between 2011 and 2016. This underscores the high intensity of water demand in Abu Dhabi. The water demand across the emirates and the volume of treated wastewater is highlighted in Figure 1 below.

Figure 1 Water demand and volume of treated wastewater in the UAE

Water reuse and Disinfection byproducts (DBPs)

During water treatment, disinfection is practiced to inactivate pathogenic microorganisms. A setback of disinfection is the production of disinfection byproducts (DBPs) by the reaction between disinfectants and residual organic matter. Over the years, carcinogenic risk has been linked to exposure to DBPs. The formation mechanism of DBP along a wastewater treatment chain is highlighted in Figure 2.

Figure 2
DBP formation mechanism in municipal wastewater treatment

Depending on the type of disinfectant in use, a wide range of DBPs can formed in water resources. Table 1 shows common disinfectants used and some of the DBPs they produce in water.

Table 1 Common disinfectants and DBPs formed in water resources

Objective of study

The overall objective of this study is to evaluate the occurrence and potential health risk of THMs in recycled water in the emirate of Abu Dhabi. The approach is segmented into 4 broad categories as highlighted below:
  1. Characterization of THMs in Treated Sewage Effluent (TSE) from the Mafraq activated sludge wastewater treatment plant in Abu Dhabi and the Membrane Bioreactor plant (MBR) in Masdar city.
  2. Toxicity evaluation of identified THMs in the TSE from the treatment facilities earlier mentioned.
  3. Evaluation of intended end uses of recycled water in Abu Dhabi.
  4. Exposure assessment and risk characterization of THM in the Mafraq and Masdar MBR recycled effluent.