Study Of The Influence Of Wastewater Sources On Water Quality In Helwan Area:

Amr Ahmed Mahmoud Nada

In developing countries like Egypt, contamination and pollution ofwater is a subject of growing concern. There are various sources ofpollution such as; disposal of agricultural drainage and domesticwastewater which constitute a major human health hazards [1]. This isbecoming of primary concern especially where mixed water is used as asource of drinking water. Therefore the enforcement of the existinglegislation on environmental aspects, and the identification of alternativestrategies for water quality management would need to be seriouslyconsidered [2]. Waste products of industrialization, urbanization andagricultural mechanization generated since 1960, have had harmful effectson the ecosystems of the country. The intensive use of chemical fertilizersand pesticides led to increasing levels of chemical residues in the terrestrialecosystem. The industrial centers in the country are becoming majorsources of pollutants [3]. Helwan area is considered as one of the industrialforts in Egypt due to the presence of some huge industrial projects, the areais characterized by the presence of many water resources such as the RiverNile, irrigation canals, the artesian wells and the sulfur and mineral springs.These water resources are used in drinking, domestic, agricultural andindustrial purposes as well as for medical treatment. This study is devotedto assess the source of recharge and mineralization of groundwater inHelwan area and to evaluate its suitability for different purposes.Introduction and Literature Review21.2. Location and ClimateHelwan area is located to the east of River Nile and south of Cairobetween latitudes (31‹ 15’ 00” - 31‹ 22’ 30” N) and longitudes (29‹ 45’00” - 29‹ 57’ 30” E) Fig.(1-1).Fig.(1-1): Sketch of Helwan area and its internal divisions.The climate in Helwan area is arid and marked by warm winter, hotsummer, low rainfall and high evaporation rates. The relative humidity ismoderate and active winds of intermediate speeds are recorded. The meanIntroduction and Literature Review3annual rainfall is in the ranges from 4.2 mm to 17.4 mm. Evaporation isgenerally high, it reaches about 18.7 mm/day in May and minimum valueof 2.3 mm/day recorded in December. The average daily temperatures varyfrom about 37.1 oC in August to about 5 oC in January. The highestrecorded value of relative humidity is 71.8% in December [4].1.3. Previous studiesThe western part of Helwan area is heavily populated and doesn’t haveany sewage system and water erupted heavily under pressure at twospecific points near an existing workshop building [5]. This water has anoffensive smell from hydrogen sulfide gas causing severe problems amongthe workers of that factory beside the effect of corrosion on the exposedfactory instruments. An investigation was made to find if there is anyrelation between shallow ground water, drainage water and erupted water.The chemical analysis indicated that the water exploding from thesespecific points is completely different from the drain water. To get rid ofthe sulfide compound, aeration, oxidation with chlorine, and treatment withferric chloride was investigated for the spring water samples in thelaboratory.The impact of liquid wastes of industrial complex at Helwan on waterquality of both Nile and canal streams was studied [6]. The samples takenwere analyzed for soluble heavy metals, suspended matter and salts. Thedata showed that the liquid wastes discharged by industrial complex atHelwan contain high amounts of heavy metals mainly Fe, Mn and Zn andhigh concentrations of soluble salts. The dumping of these industrial wastesIntroduction and Literature Review4into El-Hager and El-Khashab canals were much higher than that in theNile water by about 4 to 7 times. In addition, the concentration of Fe, Mnand Zn in the Nile water at Helwan segment were found to be 4 timeshigher than the normal concentration. It was also found that the industrialliquid seriously polluted the groundwater table in the investigated area.The water quality of the River Nile at Helwan area was studied in thetime from summer and autumn of 1991 to winter and spring of 1992 [7].Field measurements of temperature, pH, conductivity, DO, turbidity andothers were made. Routine laboratory measurements of major ions,nutrients and organic pollutants were also made. Heavy metal pollutantssuch as Pb, Cr, Cd and others were measured using FAAS and ICP-OS.The heavy element content in water was found to be within the permittedinternational limits. Seasonal variations of heavy elements in water showednormal differences.The impact of industrial wastes on water and soil quality at El-Tebbinarea and the pollution of heavy metals at Helwan area [8] was found to bedue to the dust-fall and discharge of solid and liquid wastes both indumping area, the irrigation canals and Nile stream. The large quantities ofliquid wastes from industrial activity that have been discharged into Nilestream and El-Khashab canal lead to the water pollution by the increase ofthe heavy metals and the concentration of soluble salts in water.The geology and hydrology studied of Helwan area [9]. Therapeuticproperties of springs water according to the chemical analysis of waterfrom springs in Helwan area shows that, they contain a large amount ofdissolved salts and high concentrations of H2S (40 ppm) and CO2 (28 ppm)gases. Metals such as Zn, Cu, and Al are detected in small amounts at mostIntroduction and Literature Review5springs. Radioactivity of spring water in Helwan area lies within thepermissible dose and could be of a medical value. Based on the chemicaland physiochemical properties, Helwan springs have long used for naturalmud therapy. Water of Helwan springs has proved usefulness in treatmentof chronic articular disease and certain skin disorders. Helwan new springcan also be useful in treatment of various disorders of the liver, digestivetract and metabolism.The effects of cement pollution on metal accumulation in water, soiland plants were studied in Helwan area and compared the results with thoseobtained from less polluted field (20 km north of the polluted site along theNile River) [10]. Magnesium, calcium, sodium, manganese and iron werethe most accumulated metals in polluted water, soil and plants samples.Generally, the increase in metal concentrations was in the order of Mg > Ca> Na > Mn > Cd > Fe > Pb. Zinc and copper were undetectable in thepolluted and unpolluted sites. Cobalt and potassium contents decreased inthe polluted water; however, the change in potassium was significant.The chemical pollution of the groundwater was studied in Helwan andEl-Tabbin areas [11]. The work includes a vulnerability study on thegroundwater in the southern portion of Cairo city. The study revealed that,the salinity and ion distribution vary according to the geographical positionof the examined wells and the industrial activity within the area. Two mainsuccessive zones of salinity, increasing from west to east generally occupythe area. El-Tabbin area has a more saline ground water than Helwan area.The variation of ion concentration from area to another is most probablyrelated to the ion exchange processes. Also, the seepage from the drainsand industrial wastes is of great effect on the chemical composition of theIntroduction and Literature Review6ground water in the area. Most of the industrial units are discharging theireffluents on the surface or under the ground, which through vertical orlateral seepage reach the groundwater and the Nile River and canals.The risks associated with the presence of selected contaminants in air,soils, waters and plants were studied in four locations in Helwan City [12].The results showed that water samples could be classified as C3-S1,(medium- high salinity hazard and low alkalinity hazard). Theconcentrations of Fe, Zn, Cu, Ni, Pb, V and Al in water samples werefound below the permissible limits.The effect of water pollution along different sites of the River Nile andproduction of some fresh water fishes was studied [13]. The quality ofwater collected from different sites along the River Nile in Helwan area 35km south of Cairo, where the effluents of factories are discharged wasinvestigated.The Hydrochemical characteristics and pollution of natural waterresources was studied in Helwan area [14]. The water bearing formations inthe study area were described with a discussion of their hydrogeologicalproperties. Pollution of water was discussed on the basis of detected ions oftrace and minor constituents. The study indicated that the surface water andshallow groundwater are locally contaminated especially by agricultural,industrial and domestic wastewater. Recommendations were given for theprotections of the water resources in the studied area.The Pollution of natural water was studied at Helwan area and itsvicinities [4]. The study indicated that the surface water, groundwater andIntroduction and Literature Review7natural springs are locally contaminated especially by agricultural,industrial and domestic wastewater. Water salinity in shallow groundwateris fairly fresh compared with the deep one, while the spring water is highlysaline. The total salinity of water is increasing toward north, the sulfate,chloride, calcium, magnesium and sodium concentrations increase in thesame direction. Shallow groundwater has more major constituents thanriver Nile water. Local contamination occurs at north in Ezbet El walda andat south in El Tebbin localities. All the shallow groundwater samples hadacceptable nitrate content. The Pb, Cd, Cr, Co, Mn and Ni concentrations inall water samples in the surface and groundwater (shallow & deep), werebelow the recommended level of contamination.Analytical profiling of organic and inorganic contaminates conductedin water samples in Helwan region [15]. Seven sites at the industrial area ofHelwan were selected to assess the impact of wastewater dumping directlyin the River Nile. Water samples were collected from different section atsource of pollution. Collection, preservation and measurement of sampleswere conducted according to the standard method and examination forwater and wastewater. In addition to physical parameters (temperature, pH,conductivity, turbidityc.), inorganic contaminations such as major ions(cations and anions), nutrient (sulfate, phosphate, nitrate), trace metals As,Co, Cr, Ni, Al, Fe, Cu, Mn, Pb, Zn and Cd) as well as organic contaminates(phenol, oil and grease, and total organic carbon) were also measured. Theobtained results showed that for all samples, trace metals (As, Co, Cr andNi) were not detected. On the other hand, trace metals (Al, Fe, Cu, Mn, Pb,Zn and Cd) were detected with certain concentrations. In all samples,organic contamination, such as phenol is not detected, while oil and greasein some sections were detected with certain concentration. Total OrganicIntroduction and Literature Review8Carbon (TOC) is measured to reflect the extent of organic pollution in thesamples.Helwan district lies to the southwest of Cairo-Suez structural belt and ismainly affected by faulting and slightly by folding [16]. Faulting is themain structural feature, there is three sets of faulting NW-SE (main systemaffecting the area), E-W and NE-SW, all these faults are normal faults. Thestrata are generally horizontal and the average dip ranges from 1o to 2o. Inthe vicinity of faults, the beds are locally dragged; the dip may reach 30o.Beside faults, at least two sets of important joints are dissecting thelimestone all over the area E-W and NW-SE. Folding was only produced inconsequence of the bending of beds along faults lines or in the rockdownthrown sides of faults. Neither true anticlines nor synclines of organicorigin are presentThe geochemistry of water resources and pollution problems wasstudied in Helwan area [17]. The water salinity showed a fresh water typein river Nile, irrigation canals, industrial drains and deep groundwater.While water salinity varies from fresh to brackish water types inagricultural drains and shallow groundwater. The Nile river water hadacceptable and permissible limits of contamination by heavy metals.However, most shallow groundwater, canals and drains water wereseriously polluted by some heavy metals while most deep groundwater wasslightly polluted by some heavy metals.Introduction and Literature Review91.4. Geomorphologial and geological settingsHelwan area is characterized by low relief and a gentle slope from eastto west occasionally traversed by shallow drainage lines. Ground elevationvaries between about 20m and 40m above sea level.Geomorphologically, the area is discriminated into three units Fig.(1-2); the structural plateau, the piedmont plain and the flood plain [18].Several deeply incised wadis such as wadi Hof, wadi El Gibbu, and wadiGarawi dissect the plateau. These wadis are directed to the River Nile andrun from east to west. The plateau consists mainly of limestone and isdissected by a number of faults. The Nile valley plain has a width of about5 km and is almost featureless, with maximum ground elevation of 40 mand a minimum of 20 m above sea level [18]. Helwan city lies entirelywithin these plains. The western part is intensively cultivated, where ElKhashab and El Hager canals are used for irrigation and navigation.Geologically, the surface of the study area is entirely occupied bysedimentary rocks ranging in age from Quaternary (Holocene andPleistocene) to tertiary (Pliocene - Eocene) [18]. The Holocene depositshave a general thickness of about 20m thick and is represented by Nilesilts, clays, sands and gravels, which occupy the flood plain of the Nilevalley. Pleistocene deposits are represented by clay’s marls and sand bands.Pliocene deposits are composed of fine sands, mainly limestone, sandylimestone and sandy marls. Eocene rocks constitute the most commonoutcrops in the study area. They are mainly made of limestone, marls anddolomites.Introduction and Literature Review10Fig.(1-2): Main geomorphic features within the study area. [18].1.5. Hydrology of the studied areaThe groundwater in Helwan area is tapped from the Quaternary(Holocene and Pleistocene) and the Tertiary deposits (Pliocene andEocene). The Holocene deposits (Nile silt, clay and sand) have a thicknessranging from 10 m north Helwan to 14 m southward [19], while thePleistocene deposits are mainly composed of silts, sand and gravel rangingIntroduction and Literature Review11in thickness from 50 m to the north Helwan to 80 m southward. The mainrecharge sources of the Quaternary aquifers are the infiltration from theexcess irrigation water from cultivated lands and irrigation canals such asEl-Khashab and El-Hagir canals and drains [18]. The study of [19]indicated that the Quaternary groundwater lie under a water table condition,especially on eastern side of the River Nile. The shallow pumps tap thistype of water.The Tertiary aquifers include the Pliocene and Eocene deposits. ThePliocene sediments are composed of sands, clays and calcareous,argillaceous sediments [9]. The main sources of recharge are the upwardleakage from the Eocene fractured limestone and downward leakage fromthe irrigation canals and drains Fig.(1-3).Fig.(1-3): Hydrological cross section in the studied area. [9]Introduction and Literature Review12The fracture Eocene limestone represents the main aquifer in theeastern part of Helwan area. It is composed of marl, dolomite, sandy orchalky limestone with thickness ranges from 400 m to 800 m andunconformable overlying the Cretaceous Nubian Sandstone. Severalsprings are issued in the Eocene limestone. Such springs are fed by upwardleakage from underlying Nubian Sandstone aquifer through fissures,cracks, underground channels and fault plains. The groundwater in thefractured Eocene limestone aquifer slopes generally from east to west. Dueto the karast nature of Helwan area, the groundwater flows mainlycontrolling by NW-SE fault system and underground caves or channelsrather than the regular nature of the aquifer.1.6. Hydrochemistry1.6.1. Physicochemical parameters1.6.1.1 Hydrogen ion concentration (pH)The acidity or basicity of water can be measured by its hydrogen ionconcentration, pH . The pH scale is described by the formula:pH = -log [H+] [20]When measuring pH, [H+] is expressed in moles of H+ per liter ofsolution.The pH scale ranges from 0 to 14. Substances with a pH between 0and less than 7 are acids . Substances with a pH greater than 7 and up to14 are bases . Right in the middle, at pH = 7, are neutral substances, forexample, pure water.Introduction and Literature Review13The hydrogen ion-activity in an aqueous solution is controlled byinterrelated chemical reactions that produce or consume hydrogen. Thereaction of dissolved carbon dioxide with water, which is one of the mostimportant reactions in establishing acidity in groundwater system, isrepresented by three stepsCO2 (g) + H2O (l) . H2CO3(aq) K= 10-1.43H2CO3(aq) . H+ + HCO3- K=10-6.35HCO3- . H+ + CO32- K=10-10.33Many of the reaction between water and solid species consume H+ forexample the hydrolysis of calcite,CaCO3(C) + H2O(l) . Ca+2 + HCO3- +OH K=10-3.4 [20]1.6.1.2 Specific Electrical Conductivity (EC)Electrical conductance or conductivity is the ability of a substance toconduct an electric current. Specific electrical conductivity (EC) is theconductance of a body of unit length and unit cross section at a specifictemperature. As ion concentrations increase, conductance of the solutionincreases; therefore, the conductance measurements provide an indicationof ion concentration. There is linear relation between the measured specificelectrical conductivity and the total dissolved solids ”TDS = 0.64 EC”.A simple classification of groundwater according to TDS [20] isrepresented in Table (1-1).Introduction and Literature Review14Table (1-1): Simple groundwater classification based on totaldissolved solids. [20]Category Total dissolved solids ppmFresh water 0-1000Slightly Saline water 1000-3000Moderately saline water 3000-10000Very saline water 10000-35000Briny water More than 350001.6.1.3 HardnessThe property of hardness has been associated with effectsobserved in the use of soap or with encrustation left by some types of waterswhen they are heated. The hardness value resulting is generally called”hardness as CaCO3” or ”total hardness”. Carbonate hardness includes thatpart of the hardness equivalent to the alkalinity. If the hardnessexceeds the alkalinity, the excess is termed ”noncarbonate hardness” or”permanent hardness”.1.6.2. Major ion distributionThe major ions are (Ca, Na, Mg, K , C l , HCO3, and SO4); the totalconcentration of these seven major ions normally comprises more than 90 %of the total dissolved solids in the water. Ions in water can form a numberof species due to the hydrolysis, complexaion, and redox reactions