The characteristics of wastewater for four wastewater treatment plants in Jordan, which are Al-Samra (ASTP), Irbid (ITP), Ramtha (RTP), and Wadi Hassan (WTP), were determined. The selected plants treat about 90% of the domestic wastewater in Jordan and serve more than 2 million inhabitants (WAJ, 2006). Because ASTP is the largest plant in Jordan and treat more than 76% of municipal wastewater, most of the environmental studies concentrate on the performance of this plant and the possible actions to enhance its efficiency. The plant consists of three parallel trains with total areas of 181 hectare (WAJ, 2006). There are two aerobic ponds, four facultative ponds, and four maturation ponds in each train. The other treatment plants, which are ITP, RTP, and WTP, are operated as activated sludge with different modes. In order to determine the characteristics of wastewater for the selected plants, representative weekly samples were taken from the inlet and outlet of these plants during June 2005 to March 2006. Samples were properly labeled with the plant reference number, date, and sampling location (inlet and outlet).
BOD and COD are the most important parameters used to define the characteristics of municipal wastewater. Also, TSS, NH4, and P were used for comparison purposes. Representative samples were collected very carefully to avoid agitation or any contact with air. Plastic containers were used to collect the samples. During collection and transportation the samples were ice-bounded. When the collection was completed, the samples were directly carried to the laboratory at AL-Huson College and stored in the refrigerator at 4oC. All analyses were conducted within 24 h of collection. Samples were collected, preserved, transported, incubated, prepared, and analyzed according to the Standard Methods for the Examination of Water and Wastewater (APHA, 1998). After dilution, the BOD samples were incubated at 20oC for 5 days. The change in DO concentration during the incubation period was measured to determine the BOD concentration. The amount that was used (mg/l) is an indication of wastewater strength. Closed reflux method was used to determine COD concentration, while colorimetric method was used for phosphorus measurement. In order to determine TSS and TDS concentrations for each sample, a well-mixed sample was filtered through a weighed standard glass fiber filter, and the residue retained on the filter (2|| diameter) was dried to a constant weight at 103°C to 105°C. The increase in weight of the filter represents the total suspended solids. The filtrate was evaporated to dryness in a weighed dish and dried to constant weight at 180°C. The increase in dish weight represents the total dissolved solids (APHA, 1998).
In Jordan, wastewater treatment plants are operated by the water authority. Wastewater treatment plants are requested to measure the wastewater flow as well as the concentrations of COD, BOD5, NH4—N, TSS, and phosphorus of the raw and treated wastewater. Usually, at these plants, BOD of the influent is measured daily; COD, TSS, and NH4 are measured weekly, while P measurement is unavailable in most of the plants.
Data regarding the other plants (17 plants) were obtained from water authority of Jordan (WAJ) where daily samples were collected by the laboratory staff and based on regular measurement campaigns performed during 2006 for all wastewater treatment plants (WAJ, 2006). Similar data for 6086 treatment plants in Germany also were obtained. Detailed data concerning wastewater characteristics, treatment, operations, and method of treatment for 398 treatment plants in the northern eastern districts of Germany were used for statistical purposes (DWA, 2006). The mean value of typical composition is being analyzed in this study based on 1 year (2006) sampling data of raw and treated sewage taken from the inlet and outlet of the treatment plants. The average monthly concentration for each plant was used to calculate and analyze the overall efficiency indicators.
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