STUDYING THE EFFECTS OF ALUM, LIME AND FERRIC CHLORIDE ON THE TREATMENT EFFICIENCY OF ROTATING BIOLOGICAL CONTACTORS PLANT

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1 Proceedings of the 13 th International Conference on Environmental Science and Technology Athens, Greece, 5-7 September 13 STUDYING THE EFFECTS OF ALUM, LIME AND FERRIC CHLORIDE ON THE TREATMENT EFFICIENCY OF ROTATING BIOLOGICAL CONTACTORS PLANT ABDEL-KADER AMR M., ALJEFRY M. H., ELADAWY S. M. FACULTY OF ENG., ALEXANDRIA UNIV., ALEXANDRIA, EGYPT E MAIL: amr_abdel_kader@yahoo.com EXTENDED ABSTRACT The kilo 26 wastewater treatment plant at west of Alexandria city was designed for removal of organic matter () and total suspended solids () from domestic wastewater by using Rotating Biological Contactors systems (RBC). The plant was consisted of primary clarifier, RBC panels and secondary clarifier. The plant effluent was disposed into Mariout Lake nearby the plant. The nutrient concentrations nitrogen and phosphorous in the plant effluent was exceeded the allowable limits as per local and international standards. The purpose of this study was to: (a) evaluate the treatment efficiencies of the RBC plant under different influent conditions, (b) evaluate the improvement on the efficiencies of treatment by using batch tests experiment for adding different s of Lime, Alum and Ferric chloride coagulants on both influent and effluent wastewater and (c) implement RBC plant dynamic model with coagulants additions to evaluate the nutrients removal on the plant. The GPS-X software was used to implement the RBC plant model. Two methods of precipitations (pre-precipitation and postprecipitation) were used in the RBC plant model. The results of experimental batch tests shows, the removal of nutrients were increased with increasing the coagulant up to a certain limit. Also, the alum coagulant was more efficient than lime and ferric chloride coagulants to remove the nutrients. The results of RBC plant model shows, the postprecipitations of alum and ferric chloride were more efficient than the pre-precipitations process. Also, the nutrient removal efficiency for different s of alum coagulant was ranged: from 66 to 86 for pre-precipitation and from 68 to 88 for postprecipitation. Whereas, the nutrient removal efficiency for different s of ferric chloride coagulant was ranged: from 69 to 87 for pre-precipitation and from 72 to 89 for post-precipitation. KEYWORDS: Rotating Biological Contactors, Chemical Sedimentation, Pre-precipitation, Post- precipitation, Mathematical Model, GPS-X Software. 1. INTRODUCTION Nutrients removal can be incorporated into either biological treatment or chemical precipitates. The addition of certain chemicals to wastewater produces insoluble salts when combined with phosphate or nitrogen. Pre-precipitation is simply direct precipitation by adding the coagulants before biological treatment stage. The main purpose of preprecipitation is to reduce load on the biological stage. Post-precipitation is a method that can be used to reduce nutrients in effluent wastewater. It involves an extra chemical precipitation stage after biological treatment stage. The RBC Wastewater Treatment Plant used in this study was designed to treat 00 m 3 /day of domestic sewage. The plant effluent was disposed into Mariout Lake nearby the treatment plant. The modular program used in this study is GPS-X software which is a modular, multi-purpose program for the simulation of municipal and industrial wastewater treatment plants.

2 The main objectives of this study were: Evaluate the treatment efficiencies of the RBC plant under different influent conditions to remove chemical oxygen demand (), biological oxygen demand (BOD 5), total suspended solids (), total nitrogen () and total phosphorus (). Evaluate the improvement on the efficiencies of treatment by using batch tests experiment for adding different s of Lime, Alum and Ferric chloride coagulants on both influent and effluent wastewater. Implement RBC plant dynamic model with coagulants additions to evaluate the nutrients removal on the plant model. Two scenarios were used, first for adding the coagulant before primary sedimentation tank (pre-precipitation) and second for adding the coagulant before secondary clarifier tank (post-precipitation). 2. MATERIALS AND METHODS 2.1 Experimental Plan and Influent Characteristics The experimental plan of this study was as follow: a) Measuring the influent and effluent wastewater characteristics for the RBC treatment plant to evaluated the treatment efficiency of the plant. Table 1 shows the characteristics of influent wastewater for the RBC treatment plant. b) Studying the effects of different coagulant s on both influent and effluent wastewater by using jar test facilities. The jar test simply consists of 6 jars one liter each providing with multiple stirrer units. Each test was performed on each sample three times and the averages of the three runs were then recorded. One liter of wastewater sample was put on each jar plus different s of coagulant. The sequence of operation was 5 minutes flash mixing (100 rpm) followed by 15 minutes slow mix (25 rpm) then allowed minutes of settling. The samples were collected from the supernatant layer from each jar. The lime and alum s were ranged from 1 to 3 whereas the ferric chloride s were ranged from to 90. All measurements and analysis were done based on the standard methods of the examination of water and wastewater c) Implement the RBC plant dynamic model by using GPS-X software. The operation conditions and influent concentrations of the actual RBC plant were used on the proposed model. Only alum and ferric chloride coagulants were available as a chemical addition in the GPS-X software. Two scenarios were used, first for adding the coagulant before primary clarifier tank (pre-precipitation) and second for adding the coagulant before secondary clarifier tank (post-precipitation). Table 1 Characteristics of influent wastewater for RBC plant. Parameters Influent wastewater concentrations Low Medium High ph BOD5, Total, T-P, , TDS, Model Scenarios The RBC plant model was implemented by using the GPS-X software. The model was consists of primary clarifier, rotating biological contactors unit and secondary clarifier. The model was calibrated and verified as per actual operation conditions of the RBC

3 RE of BOD,, & treatment plant. Two scenarios were used on this study. The first scenario was used for adding the coagulant before primary sedimentation tank (pre-precipitation). Figure 1 shows the layout of chemical pre-perception for the RBC plant model. The second scenario was used for adding the coagulant before secondary clarifier tank (postprecipitation). Figure 2 shows layout of chemical post-perception for the RBC plant model. Figure 1. Layout of chemical pre-perception for RBC plant model. Figure 2. Layout of chemical post-perception for RBC plant model. 3. RESULTS AND DISCUSSION 3.1 Performance of Rotating Biological Contactors (RBC) Plant. The effluent wastewater characteristics of the RBC treatment plant were measured to evaluate the performance of the treatment plant. Along the studying period, about three months of operation, the influent wastewater characteristics was varied from low, medium and high concentrations. Table 2 shows the Performance of the RBC plant for all influent concentrations. The removal efficiency (RE) of BOD 5 was ranged from 86 to 92, whereas the RE of was about 85. Also, the RE of total suspended solids () was ranged from 78 to 86 whereas the RE of total phosphors () was ranged from 65 to 76. Table 2 Performance of RBC plant for low, medium and high influent concentrations. Parameters Low influent con. Medium influent con. High influent con. Inf. Eff. RE Inf. Eff. RE Inf. Eff. RE BOD T-P BOD5 65 Low Medium High Influent wastewater concentration Figure 3. oval efficiency of RBC plant.

4 oval oval 3.2 Batch Tests Results Effects of alum, lime and ferric chloride on the raw wastewater. The jar test was used to study the effect of alum, lime and ferric chloride s on influent wastewater. Table 3 shows effects of alum, lime and ferric chloride on the influent wastewater. The, and removal efficiencies were increased with increasing the alum, lime and ferric chloride s. The removal was ranged: from 25 to 69 for alum, from 25 to 56 for lime and from 25 to 64 for ferric chloride. The removal was ranged: from 27 to 71 for alum, from 26 to for lime and from 27 to 63 for ferric chloride. Also, the removal was ranged: from 36 to 73 for alum, from 21 to 56 for lime and from 36 to 71 for ferric chloride. Figure 4 shows the relation between coagulant s with removal. Figure 5 shows the relation between coagulant s with removal. Also, Figure 6 shows the relation between coagulant s with removal. Table 3 Effects of alum, lime and ferric chloride on the influent wastewater. Alum coagulate Lime coagulate Ferric Chloride coagulant Alum Lime Ferric chlor Figure 4. Relation between coagulant s with oval for influent wastewater. Figure 5. Relation between coagulant s with oval for influent wastewater.

5 oval Figure 6. Relation between coagulant s with oval for influent wastewater Effects of alum, lime and ferric chloride on the effluent wastewater. The jar test was used to study the effect of alum, lime and ferric chloride s on effluent wastewater. Table 4 shows effects of alum, lime and ferric chloride on the effluent wastewater. The, and removal efficiencies were increased with increasing the alum, lime and ferric chloride s. The removal was ranged: from 24 to for alum, from 26 to 48 for lime and from 24 to for ferric chloride. The removal was ranged: from 25 to for alum, from 25 to 54 for lime and from 25 to 57 for ferric chloride. Also, the removal was ranged: from 26 to 65 for alum, from 22 to 44 for lime and from 26 to 61 for ferric chloride. Figure 7 shows the relation between coagulant s with removal. Figure 8 shows the relation between coagulant s with removal. Also, Figure 9 shows the relation between coagulant s with removal. Table 4 Effects of alum, lime and ferric chloride on the effluent wastewater. Alum coagulate Lime coagulate Ferric Chloride coagulant Alum Lime Ferric chlor oval Figure 7. Relation between coagulant s with oval for effluent wastewater.

6 oval Figure 8. Relation between coagulant s with oval for effluent wastewater. oval Figure 9. Relation between coagulant s with oval for effluent wastewater. 3.3 RBC Plant Model Results Treatment efficiency of alum and ferric chloride of pre-perception for RBC plant model. The RBC plant dynamic model was developed by using GPS-X software. The operation conditions and influent concentrations of the RBC plant were used on the proposed RBC plant. The model was calibrated and validated by using real data from the RBC treatment plant. Only alum and ferric chloride coagulants as a chemical addition were available in the software. Two scenarios were used, first for adding the coagulant before primary sedimentation tank (pre-precipitation). Second scenario was used for adding the coagulant before secondary clarifier tank (post-precipitation). a) Alum addition before primary clarifier Table 5 shows the removal efficiencies of alum pre-perception for RBC plant model. Figure 10 shows the relation between alum s and, and removal. The removal efficiencies of, and were increased with increasing the alum. The removal efficiencies of alum pre-perception were ranged from: 86 to 89 for ; 66 to 86 for and 71 to 85 for. It can be concluded from these results, the alum addition before the primary clarifier improve the phosphorus and nitrogen removals up to 85. b) Ferric chloride addition before primary clarifier Table 6 shows the removal efficiencies of ferric chloride pre-perception for RBC plant model. Figure 11 shows the relation between ferric chloride s and, and removal. The removal efficiencies of, and were increased with increasing the ferric chloride. The removal efficiencies of ferric chloride pre-perception were ranged from: 86 to 90 for ; 68 to 88 for and 73 to 88 for. It can be concluded from these results, the ferric chloride addition before the primary clarifier improve the phosphorus and nitrogen removals up to 88. Also it can be concluded that, using the ferric chloride as a chemical additions before the primary clarifier was more efficient than the alum addition.

7 Table 5 oval efficiencies of alum pre-perception for RBC pant model. Alum Dose Influent Concentrations Effluent Concentrations oval Efficiency Mg/l RE RE RE RE of, & Alum Dose () Figure 10. Relation between alum s and, and removal. Table 6 oval efficiencies of Ferric chloride pre-perception for RBC pant model. Ferric Chloride Influent Concentrations Effluent Concentrations oval Efficiency Mg/l RE RE RE RE of, & Fe Cl 3 Dose () Figure 11. Relation between ferric chloride s and, and removal Treatment efficiency of alum and ferric chloride post-perception for RBC plant model a) Alum addition before secondary clarifier Table 7 shows the removal efficiencies of alum post-perception for RBC plant model. Figure 12 shows the relation between alum s and, and removal. The removal efficiencies of, and were increased with increasing the alum. The removal efficiencies of alum post-perception were ranged from: 86 to 90 for ; 69 to 87 for and 73 to 87 for. It can be concluded from these

8 results, the alum addition before the secondary clarifier improve the phosphorus and nitrogen removals up to 87. b) Ferric chloride addition before secondary clarifier Table 8 shows the removal efficiencies of ferric chloride post-perception for RBC plant model. Figure 13 shows the relation between ferric chloride s and, and removal. The removal efficiencies of, and were increased with increasing the ferric chloride. The removal efficiencies of ferric chloride post-perception were ranged from: 87 to 90 for ; 72 to 89 for and 77 to 89 for. It can be concluded from these results, the ferric chloride addition before the secondary clarifier improve the phosphorus and nitrogen removals up to 89. Also it can be concluded that, using the ferric chloride as a chemical additions before the secondary clarifier was more efficient than the alum addition. Table 7 oval efficiencies of alum post-perception for RBC pant model. Alum Dose Influent Concentrations Effluent Concentrations oval Efficiency Mg/l RE RE RE RE of, & Alum Dose () Figure 12. Relation between alum s and, and removal. Table 8 oval efficiencies of Ferric chloride post-perception for RBC pant model. Ferric Chloride Influent Concentrations Effluent Concentrations oval Efficiency RE RE RE

9 RE of, & Fe Cl 3 Dose () Figure 13. Relation between ferric chloride s and, and removal. CONCLUSION The evaluation of the RBC plant was showed that, the removal efficiency was ranged from: 86 to 92 for BOD, 78 to 86 for, 65 to 76 for and 84 to 85 for. So, the nutrient concentrations in the plant effluent was exceeded the allowable limits as per local and international standards. The results of experimental batch tests shows, the removal of nutrients were increased with increasing the lime, alum and ferric chloride s up to a certain limit. Also, according to the results of the three coagulants tested; the use of alum and ferric chloride can be recommended, to achieve the required effluent concentrations of phosphorus and nitrogen in treated wastewater for the RBC treatment plant. The results of RBC plant model shows the following: a) The post-precipitations of alum and ferric chloride were more efficient than the pre-precipitations process. b) The ferric chloride as chemical additions before the secondary clarifier was more efficient than the alum addition. c) The nutrient removal efficiency for different s of alum coagulant was ranged: from 66 to 86 for pre-precipitation and from 68 to 88 for post-precipitation. d) The nutrient removal efficiency for different s of ferric chloride coagulant was ranged: from 69 to 87 for pre-precipitation and from 72 to 89 for post-precipitation. It can be concluded from this study that, the post-precipitation is more efficient than the pre-precipitation with such a small difference. Also, the ferric chloride coagulant is more efficient than alum and lime coagulants. The final recommendation for the RBC plant is using the ferric chloride coagulant in post-precipitation process to achieve the required nutrient removal. REFERENCES 1) Adalbert Oneke Tanyi-March 06. "Comparison of chemical and biological phosphorus removal in wastewater- a modelling approach". 2) B.C. PUNMIA ASHOK JAIN, August 03, Wastewater Engineering (Including Air Pollution), Environmental Engineering-2. 3) EPA 832-F , September 00, Wastewater Technology Fact Sheet, Chemical Precipitation, United States Environmental Protection Agency, Office of Water Washington, D.C. 4) Ismail I. M., Fawzy A. S., Mahmoud M. H., Halwany M. A. Combined coagulation flocculation pre treatment unit for municipal wastewater Journal of Advanced Research (12) 3, pp ) Jianheng Yu, Shaoqi Zhou, Weifeng Wang Combined treatment of domestic wastewater with landfill leachate by using A 2 /O process Journal of Hazardous Materials, Volume 178, Issues 1 3, 15 June 10, pp

10 6) Jill Crispell, Stephanie Wedekind, Sarah Rosenbaum, CEE 453, May 11, 04, Nutrient oval Project: Chemical Phosphorus oval. 7) Metcalf & Eddy, 03. "Wastewater Engineering Treatment and Reuse". McGraw- Hill Book Co., New York, International Edition. 8) Mark J. Hammer-Mark J. Hammer Jr, 05, Water and Wastewater Technology, Prentice-Hall of India Private Limited, New Delhi. 9) Patterson, R.A, 04, A resident's role in minimizing Nitrogen, Phosphorus and salt in domestic wastewater. American Society of Agricultural Engineers pp ) Phosphate removal: A novel approach, School of Biology & Biochemistry & QUESTOR Center, Queen's University Belfast. Dr J.W. McGrath & Dr. J. P. Quinn. 11) Park Ridge, 1978, Nitrogen control and Phosphorus oval in Sewage Treatment, Noyes Data Corporation, New Jersey, U.S.A. 12) Soli J Arceivala, 04, chairman Emeritus, AIC Watson Consultants, Mumbai, Wastewater Treatment for Pollution Control, Tata McCraw-Hill Publishing Company Limited, New Delhi. 13) Standard Methods for the Examination of Water and Wastewater, 19 th Edition 1995, American Public Health Association/ American Water Works Association/ Water Environment Federation, Washington, D.C.,U.S.A. 14) Stanislaw.M. Rybicki, New Technologies of Phosphorus oval from Wastewater, Zaklad Oczyszczania Wody i Sciekow ; Politechnika Krakwska; ul. Warszawska 24; Krakow. 15) Stanislaw Rybick, Stockholm 1997, Advanced wastewater treatment, Phosphorus oval from Wastewater, A literature review Joint Polish-Swedish Reports.