ELSEVIER Desalination 167 (2004) 75-86 www.elsevier.com/locate/desal

Treatment and reuse of industrial effluents: Case study of a thermal power plant

Mousa S. Mohsen Department of Mechanical Engineering, Hashemite University, Zarqa 13115, Jordan TeL +962 (5) 382-6600; Fax: +962 (5) 382-6613; email: [email protected]

Received 16 February 2004; accepted 24 February 2004

Abstract This paper presents a study of the potential of industrial wastewater reuse in Jordan's A1 Hussein thermal . A comprehensive review of the processes involved, industrial waste generation and requirements was carried out, and areas of potential improvment were identified. They include a system, blow-down system, desulfurization and finding alternative process water sources such as using sewage treatment plant effluent as make-up water. There is significant water pumped from the plant to the sewage plant and irrigation. Much of this wastewater could be treated by filtration, including reverse osmosis, and recirculated in the plant as process water. Water can very likely be conserved in the power plant by good operating practices such as preventative maintenance, good housekeeping, spill prevention, controlled storm run-off, cleaning techniques using minimum water, and a good training program to ensure program success. Since water conservation is very essential in Jordan, long-term plans should include consideration of changing the basic technology to either the combined system or gas- and/or diesel-driven at this power plant.

Keywords: Industrial effluents; Thermal power plant; Water conservation; Jordan

1. Introduction The remaining 30% can only be utilized by According to the National Atlas of Jordan, drilling wells. Depletion of water sources and the mean annual rainfall water in Jordan is concentrated exploitation of main ground water 8500 Mm 3, of which only 1200 Mm 3 can be ex- basins have led to the depletion of many water ploited. Seventy percent of this drains to the reserves and deterioration of water quality. This Jordan Valley, the Dead Sea and the Wadi Araba. is the situation in the Zarqa River basin. Intensive

Presented at the EuroMed 2004 conference on Desalination Strategies in South Mediterranean Countries: Cooperation between Mediterranean Countries of and the Southern Rim of the Mediterranean. Sponsored by the European Desalination Society and Office National de l'Eau Potable, Marrakech, Morocco, 30 May-2 June. 2004. 0011-9164/04/$- See front matter © 2004 Elsevier B.V. All rights reserved doi; 10.1016/j.desal.2004.06.115 76 M.S. Mohsen / Desalination 167 (2004) 75-86 pumping has lowered the ground water table so It has been shown that most of the selected that the river bed is dry most of the year and the industries require some treatment of their waste- main flow is wastewater effluent from the water. It is recommended to carry out further As Samra treatment plant (STP). At the same studies to establish the type of wastewater pre- time, the salinity level has increased and the treatment strategies and their estimated capital ground water in the upper strata is now polluted cost. There is a need for introduction of cleaner with all types of organic and chemical pollution technology in the selected industries. This could [1-4]. include substitution of raw and auxiliary mater- The industrial sector in Jordan used 50 Mm3 ials, water and energy saving, recirculation of of water in 1998, which accounts for 5% of the water, recovery of chemicals, improved process total water consumption during this year. A major control, waste minimization and good house- part of this was consumed by large industries keeping. such as phosphate mining; the production of Industry can be considered as a source of sig- potash, cement, ceramics and soft drinks; as well nificant amounts of reusable effluents [7-10]. as the energy sector. Almost all local industries Thus, industry should be encouraged to invest in have suffered from shortages in water supplies better water efficiency, more recycling and during the last two decades. The water shortage is management. Normalized water use indices can also the limiting factor for the establishment of be developed for each industry in order to allo- new industries as well as the expansion of certain cate only as much water as necessary to achieve high water consumption processes such as oil their production targets. shale processing [5]. In this paper the potential of industrial In a recent paper, Mohsen and Jaber [6] dis- wastewater reuse in Jordan's A1-Hussein thermal cussed the potential of industrial wastewater power station (HTPS) was investigated. A reuse in Jordan. Industrial water requirements, comprehensive review of the processes involved, wastewater production, types of pollutants in industrial waste generation and water require- industrial wastewater and the technologies for ments was carried out. Areas of potential wastewater treatment were evaluated. A total of improvements and conservation have also been 30 industries have been reviewed. The total identified. effluent from these 30 industries was estimated at approximately 10,200 m3/d. Of this amount approximately 4,400 m3/d are discharged into the 2. Industrial overview public sewerage system, which is about 3% of the Steam electric power plants are production total flow. The amounts of metals to be controlled facilities of the thermal electric power industry. A are: 6800 kg/y, 3000 kg/y, 45 kg/y, 65 kg/y, steam electric power plant product is electrical 20 kg/y, 2 kg/y, 25 kg/y, 60 t/y and 8 t/y of Cr, energy; its primary raw materials are fuel, air and Zn, Cu, Pb, Ni, Cd, Sn, Fe and A1, respectively. water. Currently, four fuels are used in a steam Nineteen industries, which discharge mainly electric power plant: three fossil fuels; , organic polluted process wastewater, are mostly , and ; and uranium, the basic food industries. Approximately 5.3 t/d of BOD fuel of commercial . are discharged from these industries. Of these The commercial production of electrical approximately 2.2 t/d BOD are discharged to the energy requires the utilization and conversion of public sewerage system and about 3.1 t BOD are another form of energy. Present-day steam elec- used for irrigation. tric power plants utilize the chemical energy of M.S. Mohsen / Desalination 167 (2004) 75-86 77 fossil fuels or the atomic energy of nuclear fuels • the production of steam to produce electrical energy in four stages. The * the expansion of the steam in a turbine which first stage consists of burning the fuel in a drives the generator unit and converting water into steam with . the of the steam leaving the from . In the second stage the high- turbine and its return to the boiler , high- steam enters a turbine . the generation of electrical energy from where energy in the form of shaft work is rotating mechanical energy removed; the turbine shaft is coupled to a gene- rator, which converts the mechanical energy into Other miscellaneous operations, such as plant electrical energy. In the third stage the steam sanitation and water treatment, are associated leaving the turbine is condensed to water, trans- with power plants. The unit processes for a ferring heat to the cooling medium, which is typical oil-fired plant are illustrated in Fig. 1. typically water. Finally, the condensate is reintro- The waste stream and water requirement are duced into the boiler to complete the cycle. Five organized according to the following unit pro- major unit processes are associated with the four cesses: fuel management, steam production, production stages of a steam electric power plant: steam expansion. Steam condensation, electricity • the storage and handling of fuel-related generation, and miscellaneous operation. The fuel materials both before and after use management unit process includes the transport,

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Fig. 1. Generalized waste and water diagram for a typical oil-fired steam electric power plant. 78 M.S. Mohsen / Desalination 167 (2004) 75-86

storage, and handling of fuel oil. Oil spills can inevitable that heat must be discharged from the result in significant power plant waste streams plant to some compartment of the environment. and water consumption. Spillage and subsequent Condensers and cooling towers are key equip- wash-down can contaminate the plant drainage ment in the power plants circulating water sys- system and consume large amounts of water. tem. The steam condensation process can produce Power plants are usually designed to recycle significant water demands and wastes if water- condensed steam for boiler feedwater as means of cooled condensation is employed. Air-cooled conserving water. Efficient plant operation condensers do not require water or generate requires boiler feedwater to be highly pure. wastewater but have a very low cooling effi- However, dissolved solids are concentrated in the ciency. The two most common types of water- recycled condensate as a result of evaporative cooled systems are once-through and closed-loop, water loss. To maintain total dissolved solids the main difference being that once-through below allowable limits for boiler operation, a systems consume more water than do closed-loop controlled amount is sometimes bled off. This systems. Once-through systems take cooling volume, called , is treated as water from a natural source, pump it through the wastewater and is replaced with high-purity condenser, and discharge the heated cooling make-up water. water to the same body of water from which it Water treatment for make-up water typically was drawn. The water temperature rise can be includes suspended solids and hardness removal, disruptive pollutant to the ecosystem of the water scale and control, and demineralization. body. Suspended solids removal usually requires such Once-through systems may also pollute operations as clarification and filtration. Hardness receiving with chemical residue. Chemi- removal is typically accomplished by lime-soda cals may be added to the cooling water before it softening, which requires the addition of lime and enters the condenser to prevent or minimize caustic soda. and phosphate are scaling, corrosion, and fouling in the condenser typically added for corrosion control. Deminerali- pipes. Chemicals added typically include phos- zation usually involves and mem- phate, lime, chromium, aluminum and zinc. It is brane processes such as reverse osmosis (RO). also common practice to add some type of Residue of all of these processes may flow to the biocide, including chlorine, to the water to wastewater treatment system along with the control the growth of slime. Residues of these rejected brine water. The treatment sludges are chemicals will be discharged from the condenser typically land filled. with the cooling water. There are no maj or chemical effluents or water If sufficient water for a once-through system use requirements associated with the steam is not available, cooling water must be recir- expansion process. However, the significance of culated within the plant in a closed-loop the process lies in its effect on plant efficiency condenser. Closed-loop water cooled condenser and, therefore, on the thermal discharge. When a systems employ some form of cooling device, water-steam cycle is used to convert steam heat such as an artificial pond or a , as an to the mechanical work of turbines, the maximum intermediate device to transfer to the theoretical efficiency that can be obtained is atmosphere. The relatively cool water can then be limited by the difference in at which recirculated in the condensers. the heat can be absorbed by the steam and dis- In addition to increased water conservation, carded after passing through the turbines. Thus to closed-loop systems also effectively eliminate the achieve any degree of power plant efficiency, it is problem of to aquatic eco- M.S. Mohsen / Desalination 167 (2004) 75-86 79

systems since they transfer waste heat to the reused -- an expense that makes wet/dry and dry atmosphere instead of to a water body. Closed- towers more attractive than wet ones. loop condenser systems include mechanical draft, Underlying most turbine corrosion problems natural draft, and fan-assisted natural draft wet are effects that tend to concentrate impurities. and dry cooling towers, cooling ponds, and spray Therefore, impurity levels in feedwater and steam ponds. must be kept down to a few ppb. Control of Although closed-loop systems do not require impurity sources, compatible system design and as great a quantity of feedwater as do once- material, adequate treatment to remove impurities through systems, they are not completely closed. and proper sampling and chemical analysis are A make-up water system is required to replace essential to corrosion control. There is general the circulating water lost through blowdown, agreement that monitoring and analysis should be evaporation, liquid carryover (drift), and leakage. done at many points of the water/steam cycle and Circulating water blowdown is required periodic- that impurities must be limited to a few ppm. ally for demineralization, as is boiler feed water Water treatment will include adding chemicals blowdown, even through circulating water is not such as phosphates and caustics to give better required to be of as high of purity as is boiler alkalinity control. The most important water treat- feedwater. Like the once-through system cooling ment, of course, is the removal of impurities with water discharge, the blowdown may contain ion exchange, media filtration and RO. water treatment chemical residues. The blow- down is typically treated as wastewater. Cooling towers are installed to avoid thermal pollution of natural bodies of water or to assure 3. Thermal electric power plant in Jordan adequate cooling in "water short" areas. There are The HTPS, owned operated by the Jordan three types of towers: wet (evaporative), dry and Electricity Authority, is the largest power plant in combination wet/dry design. Wet towers, the Jordan. HTPS was constructed and upgraded usual choice, are further divided into natural-draft during the years 1973 to 1984. The plant has four and mechanical draft. Dry cooling towers have fuel oil-fired burners with a total rated capacity of attracted attention lately, especially in "water- 363 MW plus four standby diesel turbines with a short" locations like Jordan. They are less expen- total capacity of 32 MW. The plant is located sive to maintain than wet towers, which require immediately southeast of the town of E1- chemical additives and conventional cooling. The Hashimiya, which is 3 km northeast of Zarqa. air-cooled condenser has no plume or blowdown. The plant is less than 1 km east of the Jordan Also, rising activity in has sparked Petroleum Refinery and 6 km southwest of the interest in dry cooling. Cogeneration plants often As Samra wastewater treatment plant (SWTP). tap the thermal energy, usually in the form of The surrounding area is densely populated. A steam, at an already existing facility. Use of dry schematic of the facility's steam cycle is shown cooling permits plant sitting without regard for in Fig. 2, and the water cycle is shown in Fig. 3. large supplies of cooling water. The disadvantage A significant way that the HTPS differs from a with dry cooling though is a decrease in thermal typical plant is that it does not include a water- efficiency relative to the wet cooling. cooled condenser system. Instead, to conserve Cooling towers have become the staple of scarce water, the HTPS condensers are air cooled, plant operation in place of once-through cooling. dry systems. Zero discharge is the next phase, which means Raw water for the plant drawn from five deep tower blowdowns will be cleaned and the water wells at a combined rate of 100 m3/h. The water 80 M.S. Mohsen / Desalination 167 (2004) 75-86 / r

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IOOmtm t-t-N Otep wea wllet I~y Fig. 3. Water cycle at the A1-Hussein thermal power station. M.S. Mohsen / Desalination 167 (2004) 75-86 81 is used as a coolant for bearings and other 3500 equipment, as boiler feed water, and for various 3000 plant services, including water supply for the 2500 HTPS housing estate. The water used to cool 2000 equipment is recirculated through a cooling 1500 tower. 1000 The raw water is highly saline, with an 500 0 average of 2200 rag/1 total dissolved solids 1977 1981 1985 1989 1993 1997 2001 (TDS), that increases over time as the water table YEAR drops. Fig. 4 shows the deterioration of the HTPS Fig. 4. Water quality at the Al-Hussein thermal power raw water supply quality. To be purified for use station. as boiler feed water, the water is treated in a tow- stage reverse osmosis plant and in an ion- The process wastewater treatment basically exchange plant. The RO reject water and the ion- consists of an equalization tank and an oil sepa- exchange regeneration water are discharged to the rator. The effluent either goes to the sewer facility process wastewater treatment plant. All connected to the SWTP or, generally during the other process wastewater, such as cooling tower dry season, to irrigation of trees in a green area blowdown, is discharged to the treatment plant as outside the power plant. Following treatment in a well. In addition to being saline, the process septic tank, sanitary wastewater effluent is also water contains oil residues, usually from leaking discharged into the sewers or used for irrigation. lubricating oil, spilled fuel oil and leaking fuel The wastewater effluent parameters do not oil. exceed sewer system limits, but often do exceed The raw water consumption is 2660 m3/d or irrigation standards, particularly with regard to 111 m3/h average. The estimates in the water salinity (2000 rag/l). The two primary sources of cycle are based on a consumption of 100 m3/h, salinity in the plant wastewater are the raw water which, according to HTPS, is today's average. salinity and the IE plant chemicals: about 1100 kg About 25 m3/h is supplied to the HTPS housing of hydrochloric acid and sodium hydroxide are estate and the workshops. The water is used for used daily for regeneration of the IE units. HTPS services and sanitation. It is not treated, and the may be modified in the future to separate the RO poor quality is a growing problem in households. and IE units and the cooling tower blowdown About 20 m3/h is used for cooling of bearing and saline streams. These saline streams may instead services in the plant. The water is recirculated be pumped to a brine deep-well injection pump- through a cooling tower and the blowdown (about ing station. Also, the capacity of the RO plant 10 m3/h) goes to the process wastewater treatment may be increased to reduce the use of the IE unit. plant. About 55 m3/h goes to the raw water treat- The consumption of hydrochloric acid and ment plant, which produces purified water for sodium hydroxide would, therefore, be reduced boiler make-up, etc. The plant has two steps: a two-stage RO plant and an ion-exchange (IE) significantly. plant. The treated water is collocated in a make-up 3.1. Areas for potential improvement water tank. The reject water from the RO plant and the wastewater from regeneration of the IE 3.1.1. Water treatment wastes plant are discharged to the process wastewater Ozonation and the reuse and/or improvement treatment plant. of IE resins are two state-of-the-art techniques for 82 M.S. Mohsen / Desalination 167 (2004) 75-86 minimizing water treatment wastes that have been The cooling water waste and contaminated documented in the literature [11]. The use of process water wastes can be treated by many ozone as a sole treatment for water is emerging as different methods: a reliable alternative to traditional multi-chemical • Isolate and separately treat waste streams, i.e., treatment methods because it (1) effectively oily water from clean brines and domestic controls scale, corrosion and biogrowth; (2) con- wastes. serves water; and (3) eliminates the use, storage, • Reuse treated irrigation water in the processes. and discharge of otherwise necessary treatment • Direct RO and IE and filtration backwash for chemicals. Ozonation is, however, energy separate treatment. intensive. • Treat and reuse condensation. An allotrope of , ozone is the strongest • Evaluate use of Wadi water as non-contact, commercially available oxidizing agent. Unlike one-pass cooling water. chlorination, ozonation produced no residuals. • Minimize wash-down water usage and deter- Instead, ozone has a very short half-life in water, gent additives. with simple 02 as its decomposition product. • Consider treating domestic waste on-site using Ozone is not stored for later use; it is immediately the water discharge in the process. injected into the treated water as it is produced • Evaluate recycling RO in stages to enable on-site by the ozone generator. The raw materials reuse in process. needed for generating ozone are air and electrical ° Deep-well injectbrines which are too costly to energy. treat further. The disposal of IE resins used for process • Reuse water from the equalization oil sepa- water demineralization is a growing concern. rator. However, because spent IE resins typically retain • Catch storm water, remove oil and solids and at least half their original capacity, they can be reuse as feed. reused in applications other than deminerali- zation. For example, the resins can be beneficially The actual wastewater treatments can be sum- applied to soil. Adding spent IE resins to soil marized as filtration (media and RO), oil skim- improve its cation-exchange capacity, thus ming, sewage treatment, flow control, and deep- enhancing the soil's ability to retain fertilizer. well injection. The benefits are magnified during periods of rain and irrigation. At these times, soil nutrients are 3.1.2. Water conservation lost through leaching into groundwater and Water conservation improvements identified through run-off. Because soil has little or no in the literature [12] apply to flue gas desulfuri- natural IE capacity, these losses can be excessive. zation, blowdown and water treatment systems, Plants are unable to absorb nutrients as fast as and alternative water sources. Also, water con- they leach from the soil. Farmers, in turn, add servation can be realized through general process more fertilizer to replace that lost to run-off or improvements. leaching. Adding spent IE resins to cultivated soil helps overcome this cycle of waste. The resins act 3.2. Flue gas desulfurization system water like a huge sponge that can retain nutrients until conservation they are needed by the plants. However, it must be noted that these highly cross-linked-polymer Flue gas emissions control devices, par- resins are essentially non-biodegradable. ticularly wet lime and scrubbers, are M.S. Mohsen / Desalination 167 (2004) 75-86 83 large consumers of water. However, because they control the suspended solids level. Side stream do not require high-purity water, they can receive treatment consists of treating a portion of the low-quality water in recycled from, for example, circulating water and returning it to the system. a cooling tower blowdown; this low-quality water By-product streams, such as sludge or flitter is otherwise typically considered wastewater. backwash, are not returned to the system and their Also, the use of low-sulfur fuel oil will eliminate volume must be replaced with additional make-up the need even to treat the emissions, thereby water. Make-up water treatment is primarily lime- conserving the treatment water. soda softening.

3.3. Blowdown system water conservation 3.4. Water treatment system water conservation Blowdown systems have the potential for RO demineralization systems have also been water conservation through reuse. For example, targeted as a means of water conservation. These since the boiler feedwater supply has the highest systems typically divert approximately 25% of water quality requirements of any system in the boiler feedwater flow to the drain as concentrated power plant, boiler blowdown is generally of brine. A system has been devised that recovers all higher purity than the original source of supply. of the RO effluent stream for partial make-up to Thus, untreated boiler blowdown can efficiently the cooling tower. The water that is now being be recycled for almost any other use in the plant. pumped to the sewer and used for irrigation could Treated cooling tower blowdown also has the be treated similarly to return a high percentage of potential for reuse. It has been documented [11] it to the system. Ultimately the brine backwash to be a good source of make-up and misting water from the RO unit could be deep-well injected. for flue gas desulfurization scrubbers and may also be used for bearing flush water and pump- 3.5. Alternative water sources seal water. Characteristically, the blowdown must go through a lime-softening process for treat- One way to conserve water is to generate ment; RO or IE may also be appropriate. process water sources that would otherwise be Additionally, the frequency ofblowdown and considered wastewater. For example, a few power its associated treatment can be minimized to plants have utilized seawater or sewage treatment conserve water. However, there are upper limits plant effluent as make-up water. In this case then, at which it is not possible or practical to continue the effluent from the SWTP would be a source of operating the boiler or cooling tower without plant water. blowdown due to excessive amounts of corrosion Both municipal sewage effluent and on-site scaling and fouling from high concentrations of sanitary wastewater can be recycled for make-up certain contaminants in the recirculating water. water. In some instances, more advanced treat- While the levels at which it is practicable to ment is required to remove and phos- operate can be raised by using make-up water phorous or reduce suspended solids and BOD to treatment, corrosion-resistant materials, and very low levels. These treatment techniques scaling, corrosion and fouling inhibitors, there are supplement conventional municipal treatment of still upper bounds to the permissible cycles of effluents with chlorination or ozonation. water due to ion concentration. The SWTP may discharge water that is either One way to obtain the maximum cycles of directly useable or useable after simple treatment water is by treatment of make-up water and recir- in the power plant. The quality of this discharge culating it. Side stream filtration can effectively is critical. If the sewage treatment plant effluent 84 M.S. Mohsen / Desalination 167 (2004) 75-86 is sufficiently low in salinity, consideration although the pH value is very close, but the should be given to the use of the effluent as cool- standard for irrigation is exceeded for pH, TSS ing water in the power plant. The water needs to and chlorine. be low in BOD as well so that the power plant The Zn concentration is probably not repre- would not need to construct its own biological sentative for the long-term situation. Only one treatment facility to treat the incoming sewage sample has been taken, and it appears that this plant water. The possibilities of conserving the was taken during maintenance of the plant and sewage treatment plant water by using it in the that the rest of the time the Zn content in the power plant can be evaluated technically and wastewater is low. For the purpose of estimating economically. the annual discharge of zinc, it is assumed that the average annual concentration does not exceed 0.3 mg/1 Zn. 4. Present wastewater disposal According to the analysis, the salinity of the The sanitary wastewater effluent is treated in effluent reaches 2800 mg/1 TDS. This exceeds the septic tanks and is discharged into the sewer or TDS limit of 2000 mg/1 for irrigation. Estimates during the summer period is used for irrigation of indicate, however, that the problem is severe, trees planted in a green area outside the power both technically and environmentally. There are station. The process wastewater is led to the two main sources of salinity: the raw water and wastewater treatment plant, which basically con- chemicals added to the IE plant. Assuming a sists of an equalization tank and an oil separator. water consumption of 100 m3/h and a TDS con- The effluent from the WWTP either goes to the tent of 2200 mg/1, the daily intake is 5280 kg/d sewer, which is connected to the SWTP, or TDS; also about 1100 kg of hydrochloric acid and generally during the dry season for irrigation of sodium hydroxide daily are for regeneration of trees. Table 1 shows a summary of selected aver- the IE plant. The total TDS quantity discharged is age and maximum values compared with the about 6400 kg/d. Considering the process waste- standards for discharge to sewer and irrigation. water stream, which is about 45 m3/h, the esti- The samples indicate that the standards for dis- mated TDS quantity is about 5100 kg/d, corres- charge to the sewer system are not exceeded ponding to an average concentration of 4700 mg/1

Table 1 Wastewater effluent analyses

Average Maximum Standard sewer Standard irrigation

Temperature, °C 29 36 -- -- pH 7.9 9.4 5.5-9.5 6.5-8.4 EC 1250 2650 -- -- TSS, #S/cm 104 389 1100 100 TDS, mg/1 2000 BOD, mg/1 13 43 800 -- COD (mg/l) 28 64 2100 -- FOG, mg/1 0.5 2.0 50 5 Zn, mg/l 0.3 6.75 15 2 C1, mg/l 711 -- 350 M.S. Mohsen / Desalination 167 (2004) 75-86 85

| [ ;Chemicals T Reverse ~--- osmosis Make up plant water tank exchangeplant water tank Bo!e:i Regenerationeffluent Reject ~ Atmospheric loss

20m3/h Cooling Equipment 10m3/h " Tower 1'

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I I 100m3/h Sewer f9

Fig. 5. Proposed mitigation measures.

TDS. This is much higher than measured. The of TDS above 4000 mg/l shall not be discharged reason for this may be that discharges from the IE into the sewer. Under these rules the process plant are irregular and that reportedly sometimes wastewater should not be emptied into the sewer. the effluent is being diluted. Also, discharging the wastewater into the sewer Although the estimates may not be entirely does not satisfy the general JEA policy to treat accurate, the results indicate clearly that the the wastewater and return it to the environment standards for reuse of the effluent for irrigation by using it for irrigation. It is also unsatisfactory are severely exceeded. Consecquently, the pre- to discharge very large quantities of salts to the sent irrigation practice should be discontinued as sewer, knowing that these quantities will even- it may lead to a serious contamination of the soil tually be spread through irrigation in the Jordan and groundwater resources in the area. Valley. One alternative to irrigation is to discharge all effluents into the sewer. According to JEA 5. Proposed mitigation measures reglations, this would be an acceptable solution as TDS is not officially regulated. However, the For hygienic reasons sanitary wastewater WAJ applies a set of administrative rules accord- should go into the sewer system. For the process ing to which industrial wastewater with a content wastewater the alternative options are: 86 M.S. Mohsen / Desalination 167 (2004) 75-86

• to use alternative water sources and IE backwash here are two sources of dis- • to introduce cleaner technology which will charge from the sewage treatment plant could reduce the use of chemicals in the plant potentially be recycled into the plant. • to separate and treat the wastewater Water can very likely be conserved in the • to use alternative methods of disposing of the power plant by good operating practices such as wastewater preventative maintenance, good housekeeping, It has been considered to take water from the spill prevention, controlled storm run-off, clean- JEA Azraq-Amman water transmission line, ing techniques using minimum water, and a good which is 3.8 km away. As this water has a lower training program to ensure program success. salinity level than the HTPS raw water wells, the Since water conservation is essential in consumption of chemicals in the IE unit would be Jordan, long-term plans should include considera- reduced to about one-third. The consumption of tion of changing the basic tech- nology to either the combined system or gas- and/ chemicals for regeneration of the IE plant may be or diesel-driven turbines at this power plant. reduced to one-quarter if a third stage is added to It is recommended increasing the capacity of the RO unit. It is recommended that the highly the RO plant, thereby reducing the use of the IE saline wastewater streams from the HTPS and unit. Thus, the consumption of hydrochloric acid from the Jordan Petroleum Refinery are com- and sodium hydroxide is reduced significantly. bined and that the wastewater is injected into a deep well drilled for this purpose to approximatly 1100 m depth. In the HTPS, the wastewater References system should be modified to separate the saline streams from the RO and IE units and the cooling [1] H.A. Abu Qdais and F. Batayneh, Desalination, 150 tower blowdown, and these should be pumped (2002) 99. into a new pipeline to a brine injection pumping [2] O.R. A1-Jayyousi and M.S. Mohsen, Desalination, station to be located at the the Jordan Petroleum 139 (2001) 237. Refinery. The proposed measures are shown in [3] M.D. Afonso, J.O. Jaber and M.S. Mohsen, Desali- principle in Fig. 5. The consumption of chemicals nation, 164 (2004) 157. [4] M.S. Mohsen and O.R. Al-Jayyousi, Desalination, is reduced from about 1100 kg/d to 300 kg/d. 124 (1999) 163. About 5100 kg/d TDS (salts and chemicals) will [5] J.O. Jaber and M.S. Mohsen, Desalination, 136 no longer contaminate the soil and endanger the (2001) 83. ground water . Instead, the saline waste- [6] M.S. Mohsen and J.O. Jaber, Desalination, 152 water will be injected into the deep saline strata. (2002) 281. [7] M.D. Afonso, A.M. Brites Alves and M.S. Mohsen, Desalination, 149 (2002) 153. [8] M.D. Afonso and R.B. Yanez, Desalination, 139 6. Conclusions (2001) 429. Relative to other thermal electric power plants [9] B. Durham, M.M. Bourbigot and T. Pankratz, using fuel oil in an arid environment, there Desaination, 138 (2001) 83. ll0] A.J. Karabelas, S.G. Yiantsios, Z. Metaxiotou, appears to be some significant potential for water N. Andritos, A. Akiskalos, G. Vlachopoulos and conservation at the HTPS. There is significant S. Stavroulias, Desalination, I38 (2001) 93. water pumped from the plant to the sewage plant [1 i] H. Zhou and D.W. Smith, J. Environ. Eng. Sci, 1(4) and irrigation. Much of this wastewater could be (2002) 247. treated by filtration, including RO, and recycled [12] C.D. Livengood and J.M. Markussen, Nox Control in the plant as process water. The salty filtration VII Conference, USA, 1994, pp. 1-18.