by John C. Callaway, Member of Team 1, IWP, October 2000
Original Design and Operation
The installation at Al Labbani was originally designed as a conventional water treatment plant capable of producing 3-4 million gallons/day (MGD) of high quality chlorinated potable water. It was built in 1979 and was primarily designed to remove suspended matter from raw water and disinfected it with chlorine. It was not designed to remove dissolved contaminates such as salt or industrial wastes. A summary of Al Labbani's original design will help clarify the situation at Al Labbani now. My description may not be entirely accurate but it is the best that I could get from the Iraqi engineers due to the language problem.
Originally Al Labbani operated in the following fashion. Large intake pumps located in the main building brought water in from the Shatt Al Arab located to the east of the plant. It was sent to a splitter (distribution) box located between the solids contact tanks where a weir divided the two flows equally. Alum was added at the splitter box and this initiated the formation of a floc in the tanks. This floc entrapped any suspended matter in the raw water and settled it to the bottom of the tanks. The reasonably clear supernatant was then pumped (using a high lift pump) through the pressurized sand filters.
Each pressurized filter consisted of a tank divided into two compartments by an iron plate. The upper compartment contained a filter media made of ordinary sand, garnet sand and coal of differing sizes and density. The supporting plate had 360 holes with a semispherical comb filter in each. These comb filters allowed the water (under pressure) to pass through the filter media where the last remnants of floc were removed. They kept the filter media in the upper chamber and allowed the clarified water to collect in the bottom channel.
This water was pumped to the chlorinating basin where chlorine was added to disinfect it and kill any remaining pathogenic (disease producing) bacteria. This finished water was then pumped into the distribution system to be delivered to customers or stored in an elevated storage tank. The alum sludge (mud) that collected in the bottom of the solids contact units was periodically drained off to prevent any accumulation in these tanks.
The sand filters would eventually become plugged with alum floc and had to be cleaned (backwashed) periodically. This was done by reversing the flow of water to the filter plus pumping large amounts of compressed air supplied by large blowers located in the main building. This caused great turbulence in the filter media and carried away the alum contamination which was dump down a waste drain and disposed of. When the filter was clean the compressed air was shut off and the water flow switched backed to the forward direction. The five pressurized sand filters allowed the plant to operate continuously with some filtering water while others were being cleaned.
Present Operational Status
Due to two wars and sanctions this plant is barely operating. Much of the original equipment, piping, wiring, conduit and control panels are either defunct or missing due to cannibalization for other uses. See a list of equipment problems and failure.
The only equipment that is presently functioning are the intake (sucking) and high lift pumps. At the present time the plant can only pump very turbid raw water from the Shatt Al Arab, treat it with chlorine and send it to the distribution system. The lack of a chlorinator(with its injection pump and ejector) makes chlorination very haphazard. Chlorine gas is fed directly into the chlorination basin at an unreliable rate without any means to quantitatively test for chlorine residual and the degree of bacteria kill. The rate of chlorine use (demand) to produce this residual is high because of the large amount of suspended matter in the untreated water. This demand would be much lower if the sedimentation tanks and filters were functioning. Water coming from Al Labbani should not be considered safe to drink.
Salt intrusion is a serious problem in the Shatt Al Arab because of drought and dam building in Turkey. The many petrochemical plants along the Tigris-Euphrates also contribute to this pollution. The water reclamation facilities at these industrial operations are in as bad a condition as Labbani because of the sanctions. The plant was never designed to remove either salt or industrial pollutants. A new canal bringing better quality water now exists but due to unreliable electrical power supply the plant cannot fully utilize this source.
Condition of the Portable Water Treatment Units
These units were installed to augment the process capacity of Al Labbani starting in the 1980's. Each is a miniature version of the main plant. There are 12 of these units and are mounted on concrete pads to the south and east of the main building. Most of them are defunct and need extensive repairs like the rest of Labbani. They are not covered by the $ 35,000 provided by IWP. Their total capacity is only 40% for the original Labbani plant so it is much more efficient to repair the old plant than expend resources on them.