If you want to ensure that sewage and wastewater discharge is up to the purest quality and best environmental standards, where do you place the outfall? Just upstream of the freshwater intake. That actually happened in California some years ago when a company wanted to discharge waste into a protected waterway and offered that as their guarantee of discharge purity.
Wastewater and sewage is an inevitable byproduct of human life and becomes a major problem in large-scale conurbations. There comes a point where it can no longer simply be dumped at a convenient distance from the city or in the sea untreated, where it has a nasty habit of returning to source. For an example of the former, look at the sewage lake at Briman the northeast of Jeddah and, of the latter, take in the sight and smell of the green algae on Hamra beach in south Jeddah.
A more constructive approach to sewage and waste is to see it not as a problem but as a valuable resource. It is rich in nutrients which, when recovered, can be used for agriculture. Water itself when purified is a vital resource and is perfectly drinkable. One could argue with integrity that all water is recycled due to evaporation from the seas and lakes of the world and returned as rainfall. Recycling sewage is not as outlandish a scheme as some would contend.
Modern technology is at a stage where much, if not all, of the wastewater produced by a city can be treated and reused. However, sewage treatment and reuse of treated water in the Kingdom is well behind what is possible. The current solution — happily it is changing — is to dump it in collection ponds or empty it into the sea.
Professor Omar Abu Rizaiza, Director of the Water Research Center at the King Abdulaziz University in Jeddah, expressed the view in an academic paper that Saudi standards for effluent were stringent and unintentionally imposed unnecessary limitations on disposal and reuse of wastewater. “The standards as written may actually prevent agricultural uses, and impose near drinking water quality on reuse of water. Conflicts between official standards and practical considerations cause confusion and inaccurate accounting.”
The unrealistically high requirements also frustrated the development of needed wastewater treatment facilities. He favors a redefinition of standards to free up much wasted water into reuse.
“Such would allow a variety of reuses for present wastewater production at different sites, with consequent economic growth,” he noted.
In a country under extreme water stress, wasting perfectly usable water is to waste a valuable resource, whether the water is raw sewage or treated to secondary levels.
Millions of cubic meters of wastewater effluents used to be produced and disposed of without reuse. This was not for technical reasons, but because it was unclear whether the effluents were pure according to Islamic views, even after removal of impurities by proper treatment. After lengthy investigations and discussions with scientists and specialists, the Council of Leading Islamic Scholars (CLIS) of Saudi Arabia issued a special fatwa as far back as 1978 (CLIS 1978) that said that:
“Impure wastewater can be considered as pure water and similar to the original pure water, if its treatment using advanced technical procedures is capable of removing its impurities with regard to taste, color and smell, as witnessed by honest, specialized and knowledgeable experts. Then it can be used to remove body impurities and for purifying, even for drinking.”
Jeddah produces about 500,000 cubic meters a day (cmd) of sewage. In 2005, 300,000 m3 was collected by the municipality mains system while 200,000cmd would be left in the ground — cesspools and the like. Some 50,000 cmd was collected by the infamous yellow “honey wagons” and disposed of in Briman lakes.
Municipal treatment capacity was only 200,000 cmd and 100,000 cmd went into the Red Sea.
There are three plants in the Khumrah complex, one of 40,000 cmd and another of 60,000 cmd that together process 100,000 cmd. The 40,000 cmd plant is a rehabilitated 10,000 cmd plant that during its refit brought the discharge quality of the plant up to internationally acceptable standards. A third plant, Khumrah 3, is a 140,000 cmd plant.
There are five more smaller plants scattered around the city that can handle 100,000 cmd between them so the treatment capacity went from 200,000 cmd to 340,000 cmd in 2005.
The Khumrah plants produce secondary treatment water, acceptable to local standards, for disposal in the sea. It could be used for agriculture and industry, but not for human consumables and is classified as “restricted use only.”
Khumrah 4 is planned with a capacity of 250,000 cmd. The total in the south will be 500,000 cmd — way beyond the collection capacity. The 300,000 cmd is totally treated. However, waste still finds its way into the ground as cesspools overflow.
The ground under Jeddah receives 150,000 cmd a day of sewage plus 150,000 cmd of clean water from leakages in the freshwater distribution network.
According to a study by Global Water Intelligence, “effluent from the Jeddah treatment plants is discharged into the sea, although around 30,000 cmd from Khumrah is tertiary treated with reverse osmosis and sold as irrigation water.”
Their studies conclude that, “In total around 260,000 cmd of tertiary treated wastewater is thought to be currently reused in the Kingdom. A much larger volume — perhaps around 1.6 million m3/d is reused informally without tertiary treatment.” In December 2004, Abdullah Al-Muallimi, then mayor of Jeddah, announced the end of raw sewage dumping in the huge 15-million cubic-meter lake to the east of Briman.
“Today and in future, the inland lake will cease to receive raw sewage, which will instead be pumped to sewage treatment plants,” he said, signaling the imminent end of the convoys of sewage tankers clogging the city’s streets. They are still very much in evidence.
He added that the plans to increase mains sewerage in Jeddah from its current 30 percent coverage was on course to rise to 75 percent “within five years.” Certainly the work is in progress. Elsewhere in the Kingdom, projects are under way to address the use of sewage and change the perception of waste from a problem to a resource.
The Advanced Wastewater Treatment Plant, north of Dhahran is able to recycle 10 million gallons a day (mmgd) of high quality tertiary water for irrigation purposes, saving approximately three billion gallons of precious groundwater every year. Twenty-four sand filters — relatively simple technology — were used in this project.
Dhahran North Sewage Treatment Plant (NSTP) and the Advanced Wastewater Treatment Plant (AWTP) combined add 40 percent to the plants’ treatment volume capacity and will contribute to the annual saving of billions of gallons of groundwater.
The Dhahran NSTP has been expanded from eight mmgd to 10 mmgd to meet anticipated demand by the year 2010. In line with original plans to increase the recycling of tertiary water, the AWT plant has been expanded from three mmgd to 10 mmgd.
Work at the NSTP included the installation of two additional settling tanks and a bypass overflow line to divert effluent to the emergency pond during heavy rains. About three mmgd of the NSTP secondary effluent is further treated at the tertiary level to irrigate the community’s planted areas.
Increasing the rate of wastewater collection, treatment and reuse is a key of Saudi water sector strategy. The auguries are good; there is evidence of a real drive to capitalize on that most precious resource: Water.
