The Environmentalist, 22, 5965, 20022002 Kluwer Academic Publishers. Manufactured in The Netherlands.

Three Egyptian industrial wastewater management programmes

FATMA A. EL-GOHARY, RIFAAT A. WAHAAB, FAYZA A. NASR and HAMDY I. ALINational Research Centre, Tahrir Street, Dokki, Cairo, Egypt

Summary. A pre-treatment programme for wastewater from factories, representing three main industrialsectors in Egypt, has been developed. The rst case study was a factory producing potato-chips. Wastewaterdischarged from this factory was characterized by high values of BOD, SS and oil and grease (6000mgO2 l1, 6577 mg l1 and 119 mg l1 respectively). Chemical treatment using lime and lime aided bypolyelectrolyte achieved good results. Residual values of BOD and SS after treatment were 97 mg l1

and 49 mg l1, respectively. Oil and grease concentrations were reduced by 91 percent. Treatment viaactivated sludge at a detention time of 4 hrs produced good quality efuent. The second case study was anautomobile company, representing the metal nishing industry. Analyses of wastewater samples from thedegreasing, phosphating and painting departments, as well as the end-of-pipe efuent were conducted.The end-of-pipe efuent contained high concentrations of oil and grease (366 mg l1), phosphorous(111 mg l1) and zinc (81 mg l1). Chemical treatment of end-of-pipe wastewater using ferric chlorideaided by lime, produced high quality efuent. The third sector was the chemical industry. For this purposea paint factory was selected. Characteristics of raw wastewater varied widely according to the productionrate. Average values of COD and BOD were 1950 mg l1 and 683 mg l1. Oil and grease ranged from63 to 1624 mg l1. Chemical treatment using ferric chloride in combination with lime at the optimumoperating conditions achieved good results. Residual values after treatment of COD, BOD and oil andgrease reached 120, 36 and 8.6 mg l1, respectively. An engineering design for each case study has beenprepared.

Keywords: industrial wastewater treatment, food, chemicals, metal nishing

Introduction

Egypts population in 1992 was about 54 million. Itis expected to reach about 67 million by the year2000 and about 9095 million around 20252030.At present, 99 percent of the population lives on4 percent of the land which is not classied asdesert. With the very high population density in thevalley and delta, major efforts have been made bythe government of Egypt to construct new indus-trial communities in the desert to act as new polesof attraction, to create new job opportunities, and

Drs. Fatma A. El-Gohary, Rifaat A. Wahaab (the author forpurposes of correspondence) and Fayza A. Nasr work at thewater pollution research department of the National ResearchCentre, Egypt. Dr Hamdy I. Ali works at the Faculty ofEngineering, Ain Shams University, and Cairo, Egypt (e-mail:rawahaab@hotmail.com).

to protect the fragile ecosystem of the Nile valleyand the delta from further degradation.

One of the major problems facing these newcommunities is the potential health and environ-mental hazard posed by industrial wastewater.Untreated wastewater discharged by industrialactivities is often contaminated by a variety oftoxic or otherwise harmful substances. Thesewastes can damage the sewers and interferewith the treatment facilities. Moreover, persis-tent untreated pollutants passing through thesesystems may contaminate receiving water bodiesand increase the environmental risks and the costof sludge treatment and disposal. The undesir-able effects of these hazardous chemicals can beavoided by pre-treatment of the wastewater priorto discharge into the sewerage system.

60 El-Gohary et al.

Table 1. Basic information about the selected factories

Item Food Metal Chemicals

Product Potato-chips Cars Paints and allied productsProduction rate 1 t/day 8000 Car/year 1080 t/monthNumber of employees 400 300 23Working shifts/day 2 2 1Working hours 9/shift 9/shift 9/shiftWater consumption m3/day 740 80100 26.5Wastewater discharge m3/day 698 80 20.5

A wastewater management plan was, therefore,prepared as a component of an overall environ-ment management plan for one of these newindustrial communities, as a model to be repli-cated in other cities. The Sixth of October City wasselected for this purpose. The city has an indus-trial area, which will encompass 847 factories rep-resenting almost all industrial sectors. Two hun-dred and sixty eight factories are productive and32 are now under construction, while the rest arestill being planned.

Food-processing, metal nishing and chemicalwastes usually contain organic and inorganic mat-ter in varying degrees of concentration (El-Goharyet al., 1989). Since these wastes differ from domes-tic sewage in general characteristics, pre-treatmentis required to produce an equivalent efuent(El-Gohary et al., 1993; Kori and Gupta, 1994;Soheil, 1995).

For this study three factories, representingthree major industrial sectors in the city underconsideration were selected (Table 1). Labora-tory experiments have been carried out to rec-ommend the pre-treatment required. Compositesamples from the different departments and nalefuents were collected. Physico-chemical anal-yses were carried out according to the APHA(1992). Treatment via chemical coagulation andactivated sludge has been investigated.

Results and discussion

Potato-chip factory

On of the most polluting factories in the foodindustry sector is that related to the production ofpotato-chips. This end-of-pipe efuent containedhigh concentrations of suspended solids, rang-ing from 1902 to 6577 mg l1 with an average

value of 3210 mg l1. Biological oxygen demand(BOD) values varied from 2040 to 6000 mgO2 l1. Oil and grease concentrations were rel-atively high. The wastewater was slightly acidic.The pH value ranged from 4.5 to 6.5. Sedimen-tation of the nal efuent achieved 75 percentremoval of suspended solids. Corresponding BODremoval was only 19 percent. Chemical treatmentusing lime and lime aided by polyelectrolyte wascarried out (Table 2). Available results indicatedthat the residual values of BOD, chemical oxy-gen demand (COD) and suspended solids (SS)were 97 mg l1, 230 mg l1 and 49 mg l1, respec-tively. Oil and grease concentration was reducedby 100 percent.

Biological treatment using activated sludgewas also investigated (Table 3). Available resultsindicated that good quality efuent could beobtained at a detention time of 4 hrs. Treatabil-ity study revealed that high quality efuent couldbe obtained using both treatment schemes. How-ever, the use of chemical treatment has been rec-ommended for simplicity of operation and main-tenance. An engineering design for the selectedscheme has been prepared (Fig. 1).

Automobile factory

The second case study involved wastewater dis-charged from an automobile company. A eld sur-vey indicated that the major sources of pollutionwere degreasing, phosphating and painting opera-tions (Table 4). Results of the analyses of waste-water discharged from the painting departmentwere characterized by the high content of organiccompounds. Mean values of COD and BOD were1882 and 920 mgO2 l1, respectively. Oil and

Wastewater management programmes 61

Table 2. Chemical treatment of end-of-pipe efuent of potato-chip company

(350 lime+05 nalco)250 mg l1 lime mg 11

Parameters Unit Raw Treated %R Raw Treated %R

pH-value 5 99 53 801 Chemical oxygen demand mgO2 l1 7320 1275 83 5796 230 96Biological oxygen demand mgO2 l1 2100 483 77 2530 96 96Total kjeldahl nitrogen mg N l1 1323 857 35 144 95 93Total suspended solids at 105C mg l1 3210 102 67 3450 49 98Volatile suspended solids at 550C mg l1 2498 72 97 1321 26 98Settleable solids after 30 minutes ml l1 100 ND 100 408 35 91Oil and grease mg l1 336 24 29 77 ND 100Sludge analysisSludge volume ml l1 54 67Total sludge weigh at 105C g l1 29 34Volatile organic matter % 77% 728Sludge volume index (SVI) 182 1998

The results are the mean values of ve samples. ND: not detected. R: removal.

grease ranged between 42 and 334 mg l1, respec-tively. Wastewater discharge from the degreasingand phospating process contained high concentra-tions of phosphorous, (68 to 120 mg P l1) and oiland grease (up to 200 mg l1). Characterizationof the nal efuent indicated those four parame-ters namely; COD, oil and grease, phosphorus andzinc exceeded the national standards. Average val-ues of COD, BOD and phosphorous were 1087,365 and 110 mg l1, respectively. Zinc concentra-tions ranged between 36 and 191 mg l1, with anaverage value of 81 mg l1.

Table 3. Biological treatment of end-of-pipe of potato-chip company

Settled 2 4 2 24Parameters Unit waste-water Initial hours hours hours hours

Chemical oxygen demand mgO2 l1 3024 2700 900 525 251 165Removal % 11 70 83 92 95Biological oxygen demand mgO2 l1 1650 1320 645 198 115 59Removal % 20 61 88 93 96Total suspended solids at 105C mg l1 820 600 321 150 47 42Removal % 27 61 82 94 95Sludge analysisSludge volume ml l1 300 230Total sludge weight at 105C g l1 35 19Volatile organic matter % 42% 56%Sludge volume index (SVI) 86 121

After two hours settling. Aeration for two minutes followed by sedimentation.

Chemical treatment of for the painting depart-ment efuent and the nal efuent was carriedout using lime in combination with ferric chloride.COD, BOD and SS of the wastewater dischargedfrom the painting department were reduced by97%, 97% and 88%, respectively. The chemicaltreatment of the end-of-pipe wastewater using30 mg l1 FeCl3+140 mg l1 CaO produced highquality efuent (Table 5). COD, total phosphorusand zinc removal values were 93%, 92% and 97%,respectively. An engineering design for the pro-posed treatment is presented in Fig. 2.

62 El-Gohary et al.

Figure 1. Flow diagram of wastewater treatment plant (elevation and plan) for potato-chip factory (ms = metres; INF = inow;EFF = efuent).

Table 4. Characteristics of wastewater discharged from the automobile company

Degreasing andPainting dept. phosphating dept. Final efuent

Parameters Unit Min. Max. Aver. Min. Max. Aver. Min. Max. Aver.

pH-value 66 73 702 81 726 81 Chemical oxygen mgO2 l1 1365 2352 1882 1704 2262 2155 4275 2694 1087demand

Biological oxygen mgO2 l1 525 1260 920 75 116 955 221 730 365demand

Total phosphorous mg P l1 11 80 352 68 120 967 135 160 110Total residue at mg l1 856 1892 1362 1369 2166 1776 890 2029 1610105C

Total dissolved mg l1 395 1626 1014 1273 1898 1543 461 1432 907solids at 105C

Total suspended mg l1 168 496 269 96 340 235 154 1568 703solids at 105C

Oil & grease mg l1 42 3348 175 20 200 169 67 207 118Zinc mg l1 05 22 11 36 191 81Nickel mg l1 015 02 017 3 27 25Lead mg l1 02 03 023 02 15 07Copper mg l1 01 013 011 02 11 07Chromium mg l1 01 01 005 01 011 01Cadmium mg l1 005 005 005 009 005 005

The results are the mean values of ve samples.

Wastewater management programmes 63

Table 5. Chemical treatment of end-of-pipe wastewater of automobile company. Optimum dose:(140 CaO + 30 FeCl3) mg l1

Raw Treated %Parameters Unit wastewater efuent removal

pH 79 82Chemical oxygen demand mgO2 l1 1152 792 93Biological oxygen demand mgO2 l1 585 496 915Total phosphorous mg P l1 120 10 916Total residue at 105C mg l1 1471 282 808Total volatile residue at 550 mg l1 782 216 72Settleable solids after 30 minutes ml l1 75 Nil 100Oil and grease mg l1 260 168 933Iron mg l1 47 975 84Zinc mg l1 94 032 97Nickel mg l1 035

64 El-Gohary et al.

Table 6. Chemical treatment of end-of-pipe wastewater of Paints Company. Optimum dose:(50 FeCl3+140 CaO) mg l1

Raw Treated %Parameters Unit wastewater efuent removal

pH 75 82 Chemical oxygen demand mgO2 l1 1590 165 90Biological oxygen demand mgO2 l1 475 73 89Total suspended solids at 105C mg l1 168 46 73Total volatile solids at 550C mg l1 124 41 67Settleable solids after 30 minutes ml l1 5 ND 100Oil and grease mg/L 235 86 96Sludge analysisSludge volume ml l1 170Total sludge weight at 105C g l1 19Volatile organic matter % 79Sludge volume index (SVI) 89

The results are the mean values of ve samples. ND: not detected.

Paints and allied products

The third case study involved a company pro-ducing paints and allied products. Characteristicsof the raw wastewater varied widely according tothe production rate. The COD ranged from 459to 3800 mg l1, with an average value of 1590mg l1. Corresponding BOD values ranged from

Figure 3. Schematic ow sheet to show chemical feed arrangement, rapid mixing and settling tanks for paints and allied productscompany (elevation).

285 to 1290 mg l1, with an average value of475 mg l1. Oil and grease uctuated between63 and 1624 mg l1, with an average of 235mg l1. Chemical treatment of the nal efu-ent using ferric chloride in combination with limeachieved good results at an optimum pH around8.2 (Table 6). The optimum dose varied accordingto the strength of the wastewater. Characteristics

Wastewater management programmes 65

of the treated efuent were within the permissi-ble limits. After treatment, residual COD was 165mg l1. BOD value reached 73 mg O2 l1. Oil andgrease concentrations were 8.6 mg l1. Differentengineering alternatives to improve the perfor-mance of the existing situation were proposed.The scheme given in Fig. 3 was selected.

References

APHA (American Public Health Association) (1992) StandardMethods for the Examination of Water and Wastewater, 18thed., Washington, DC.

El-Gohary, F.A., Abou-Elela, S.I. and Ali, H.I. (1989) Wastew-ater management in the automobile industry. Wat. Sci.Techn. 21, 22563.

El-Gohary, F.A., Abou-Elela, S.I., El-Kamah, H.M. and Ali,H.I. (1993) Management of wastewater in light vehiclemanufacturing company in Egypt. Environ. Technology Let-ter 14, 13545.

Kori, M.M. and Gupta, S.K. (1994) Treatment of wastewaterfrom a paint industry using polyelectrolytes. 9th Proc. Ann.Conf. Hazard Rem., 1549.

Soheil, N.M. (1995) Treatment of the industrial wastewaterproduced from the yeast industry. Proc. Second Middle EastConf. on Wastewater Management. 859.