Transport kinetics of bromoform formed in desalinated water

Drinking water produced from desalinating coastal seawater is characterized by high bromides and low organic precursors. The main formed chlorination byproduct in this case is bromoform. A recent study evaluated such byproducts in the desalinated water of a coastal city in United Arab Emirates and reported low levels of most byproducts but bromoform. The levels of formed bromoform at locations far from the desalination plant were generally less than their levels in the desalination plant indicating bromoform attenuation in the distribution system. A series of lab experiments were conducted to verify such phenomena by evaluating the bromoform formed in the same desalinated water when transported in a simulated pipe environment. Results were obtained for different hydraulic conditions; such as flows and pipe diameters as well as for varying dosages of spiked chorine. The dynamic effects associated with the transported water in pipelines were found to clearly causing bromoform hydrolysis and attenuation. The initial growth of bromoform followed by its decay was successfully modeled using a first-order saturation growth rate considering a newly developed time-dependent ultimate concentration. The ultimate concentration was related to the prevailing hydraulic conditions using the well known wall and mass transfer coefficients. Such formulation allowed to favorably simulating the bromoform formation in the desalinated water under various dynamic conditions including the static condition of zero flow. Copyright ASCE 2006.