Advance Topics on Urban Water Systems Modeling; Part I: General Introduction

Engineers, scientists, modelers and administrators involved in water pollution control and water systems design and analysis frequently use state-of-the-art computer models to resolve real pollution problems and for eco-system restoration, or use this computer software for the purpose of surface water quality modeling and modeling impacts on aquatic systems and habitats and even urban drainage system design and analysis.It is well known that the number one humanity ( health) and society ( economy) enemy is hydrogen sulfide ( WANTED DIED OR ALIVE).

Hydrogen sulfide (“sewer gas” ) is a colorless gas with a rotten-egg odor. Some people can smell hydrogen sulfide at very low levels, as 0.5 parts per billion (ppb) in air. Most hydrogen sulfide in the air comes from natural sources. It is produced when bacteria break down plant and animal material, often in stagnant waters with low oxygen content such as municipal drainage systems, and domestic septic tanks. Sewers, septic tanks, livestock waste pits, manholes, well pits, and trucks that transport chemical wastes may release highly toxic hydrogen sulfide gas. For example, Improperly designed systems (septic tank) is like designing a special heterogeneous and homogeneous reactor for the production of highly toxic Dissolved hydrogen sulfide. Another example is the old sewer system in the East side of the city of Hamilton where the rotten egg smell of Hydrogen Sulfide is becoming a landmark of the city.This is probably because the design engineers in those days were actually planning for a future biochemical reactor for the production of Hydrogen sulfide.

It seems that to have the right policy, legislation, permitting and enforcement , all computer models used by design engineers must have a proper understanding of the relationship between water and Hydrogen sulfide (similar molecular geometry with the only difference that the S atom is replaced by O atom), the chemical (Henry constant , vapor pressure of H2S) and hydrodynamical ( water velocity in urban drainage system) effect on the generation of Hydrogen sulfide. So many Sewage treatment works are reported and subject to a range of parameters (during computer modeling) governing the quality of effluent and sludge produced. Because an additional product from treatment plants is odorous air (The culprit).They claim that during computer modeling the causes, source, formation and measurement of odour are widely reported and reasonably understood. I think an advance studies are still needed. For example ,the understanding of the prediction of the atmospheric concentrations of these odorous air compounds downwind of the source. This study will consist of four parts.This is the first.