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Newsletter and Technical Publications
<International Source Book On Environmentally Sound Technologies
for Wastewater and Stormwater Management>

2.1 Wastewater characteristics (Topic a)

The characteristics and volume of wastewater in West Asia countries depends upon the water supply coverage, availability and cost. Due to the shortage of water, the volume of wastewater produced per person is smaller than that produced in the European countries. Water consumption for most of the West Asia is low and it is estimated to be around 100 liters per person per day. As a result the concentration of the physical, chemical, and biological consistuents will be higher, in cases where sewer systems are available. In rural and poor areas the situation is completely different. The availability of minimum sanitation facilities and very low water consumption rate coupled with the lack of collection system affect to a great extent the wastewater characteristics. The degree of urbanization and industrialization and the disposal of industrial and stormwater to domestic sewer network will also affect the characteristics of wastewater.

Wastewater production and characteristics vary from country to country, from rural to urban areas and from city to city. The coverage of sanitation facilities and sewage networks is greater in oil producing countries; and greater still in major cities compared with secondary cities and rural areas. In urban areas, the sanitation services cover more than 85% of the houses while in rural area the coverage is only about 25% (Table 2.1).

Table 2.1: The population of West Asia countries, percent of urban population, percent of population connected to sewer systems, domestic and industrial water supply, and volume of wastewater produced and portion used in irrigation  

The organic, solids and nutrients loading of the wastewater in the West Asia region vary from country to country and vary also according to location within the country and with time. Table 2 shows typical wastewater characteristics in some selected countries of the region. The 5- day biological oxygen demand (BOD5) ranges from 280 to 570 mg/L with an average of 530mg/L; total suspended solids (TSS) ranges from 300 to 700 mg/L with an average of 453 mg/L; the ammonia - nitrogen (NH4- N) ranges from 45 to 110 with an average value of 75 mg/L. These values are very high when compared with the average US concentrations. It can be noted that a significant portion of the salinity loading in the wastewater is associated with the background salinity in the water supply.

The high concentration of these pollutants characterize the sewage of high strength wastewater which are typical of areas in which water use rates are moderately low. Dividing the observed wastewater concentration by the per capita water consumption rate (which is around 100 lpcd) gives typical loading for organic, solids and nutrient composition of wastewater (Table 2.2).

In some locations (poor urban areas and refugee camps), the concentration of pollutants is very high where TSS exceeds 3000 mg/L. The situation is also different in areas that are not connected to the public sewage network or in rural areas. Most of them use on-site sanitation technologies such as pit latrines, pour flush toilets and septic tanks. The septic tank is the most common method where a sealed concrete chamber receives all household wastewater.

Table 2.2: Wastewater characteristics and per capita loading of most countries in the West Asia region

Parameter

Unit Avg. Range US Avg. Water consumption (Lpcd) Per capita Loading g/c-d
BOD5 mg/L 530 280-750 192 100 53
TSS mg/L 453 300-700 181 100 45.3
NH4-N mg/L 75 45-110 13 100 7.5
Total N mg/L 100 80-120 34 100 10
Total P mg/L 15 10-20 9.4 100 1.5
TDS mg/L 1000 620-1300 - 100 100
Cl mg/L 260 125-350 - 100 26
Na mg/L 180 95-240 - 100 18
S mg/L 70 12-115 - 100 7
Br mg/L 0.43 0.15-0.6 - 100 0.04

Special tanker trucks are available to empty and dispose the sludge to wastewater treatment facilities or receiving points.

In practice these septic tanks are not completely sealed allowing more infiltration into the ground, which produce a very high strength wastewater. The black water that is disposed of in latrines is all allowed to decompose in the pits. Usually, when these pits are filled, they are sealed and enclosed and new pits will be dug.

Non sewered areas of Jordan, Lebanon, Syria, the Gulf States and partly Egypt and Iraq use septic tanks or cesspool. The main risk in their use is the seepage to groundwater, specially if the water table is shallow or these pools are excavated in limestone formation.

The disposal of industrial wastewater to the public wastewater network is very limited for two reasons. First; many countries like Jordan, Saudi Arabia, Egypt, and UAE do not allow industries to dispose their wastes to public wastewater network unless they comply with certain standards and must be compatible with the sewage treatment system. Second, most of the West Asia countries are considered non-industrialized countries with the exception of Egypt, Iran, and Iraq. In addition, most of their industries are light and concentrating on food processing, dairy products and soft drinks. Other industries that produce material wastes such as paper, steel, cement, paint, chemical, fertilizers, and plastic are not allowed to discharge their waste to the municipal sewer. Instead they must have their own treatment plants and recycle or reuse their wastewater on-site. Hazardous industries are encouraged to treat and dispose their wastewater through evaporation, drying and incineration. In some industrial areas near Amman (Jordan) and Damascus (Syria) and Cairo (Egypt), the high concentration of TDS, COD, and BOD are the result of a much higher fraction of industrial waste that are allowed to be discharged in the waste stream. In Jordan, Saudi Arabia, Egypt, and UAE the dairy processing and paper industry treat their wastewater on-site and recycle the effluent or reuse it for agriculture.

In many countries, e.g. Egypt, Jordan, Saudi Arabia, Syria, and UAE, the new planning policy is to confine industry to what is called industrial cities. These cities are equipped with sewer pipeline networks and treatment facilities. Depending on the type of effluent of each industry, a pre-treatment facility is recommended.

Not all major cities in the southern part of the region are equipped with stormwater drainage systems because of rare rainfall events. One or two rainfall events in Cairo do not justify construction of stormwater sewer networks. Only some major and coastal cities in the region are provided with these networks. Where such facilities exist they are separated from the wastewater sewer system except Tehran (Iran) where both networks are connected. The Jordanian legislation does not allow stormwater connection to the main sewer network.

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