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Modification of the Multi-Stage Treatment (Anaerobic- Anoxic- Oxic) by Adding Almond Shells as Biological Carriers


  • Raghad Alshalabi Department of Environmental Engineering, Faculty of Civil Engineering, Al-Baath University, Homs, Syria.
  • Rasin Zakieh Department of Environmental Engineering, Faculty of Civil Engineering, Al-Baath University, Homs, Syria.
  • Naeima Ajib Department of Environmental Engineering, Faculty of Civil Engineering, Al-Baath University, Homs, Syria.



Almond Shells, (Anaerobic- Anoxic- Oxic) A2O Treatment, Biofilm, Biological Carriers, Carbon Source


In this study, the treatment process Anaerobic- Anoxic- Oxic (A2O) was modified by adding almond shells as biological carriers. The performance of it has been evaluated in two groups for simultaneous removal of organic matter and nutrients (nitrogen and phosphorous) from wastewater. In both groups the hydraulic retention time (HRT) was 12.5 hours and mixed liquor suspended solid (MLSS) was 2000 mg/L. In the first group: The Oxic bioreactor was filled with packing up to 7% on an effective volume basis. In the second group: All bioreactors were filled with packing up to 7% on a volume basis for each tank. The efficiency of the two groups was compared by analyzing the removal efficiencies of COD, SS, NH4+-N, PO4-3. The removal efficiency in the first group was 94.71%, 90.52%, 95.73% and 92.55%, respectively, while in the second group was 96.53%, 89.82%, 98.29% and 95.61%, respectively. The treatment when adding shells in all bioreactors is the best, but the SS removal efficiency decreased slightly, the reason for this is due to the degradation of shells (organic matter). Obtained results indicated the good stability of the modified system without adding any external carbon sources whereas the almond shells have the ability to release carbon. Almond shells have the ability to adsorb pollutants and they were excellent carriers for bacteria (Biofilm).


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Ghasemi SM, Esmaeili P, Chenar MP. Enhancement of A2O Process with Integrated Fixed-film Activated Sludge (by GPS-X). 7th Int Conf Chem and Chem Eng. 2020.

Bai Y, Zhang Y, Quan X, Chen S. Nutrient removal performance and microbial characteristics of a full-scale IFAS-EBPR process treating municipal wastewater. Water Sci Technol. 2016; 73(6): 1261–8.

Wang C, Liu Y, Lv W, Xia S, Han J, Wang Z, et al. Enhancement of nitrogen removal by supplementing fluidized-carriers into the aerobic tank in a full-scale A2/O system. Sci Total Environ . 2019; 660: 817–25 :

Metcalf &Eddy. Wastewater Engineering Treatment and Resource Recovery. Fifth Edit. McGraw-Hill Education; 2014. 2018 p.

Wu C, Peng Y, Wan C, Wang S. Performance and microbial population variation in a plug-flow A 2 O process treating domestic wastewater with low C/N ratio. J Chem Technol Biotechnol. 2011; 86(3): 461–7.

Zhang W, Xiao B, Li Y, Liu Y, Guo X. Effects of return sludge alkaline treatment on sludge reduction in laboratory- scale anaerobic – anoxic – oxic process. J Biotechnol . 2018; 285: 1–5.

Guo J, Fang F, Yan P, Chen Y. Sludge reduction based on microbial metabolism for sustainable wastewater treatment. Bioresour Technol . 2020; 297: 122506.

Ayol A, Yurdakos OT, Gurgen A. Investigation of municipal sludge gasification potential: Gasification characteristics of dried sludge in a pilot-scale downdraft fixed bed gasifier. Int J Hydrog Energy. 2019 Jun 28;44(32):17397-410.

Manu DS, Kumar TA. The combined effects of C/N ratio, suspended biomass, hydraulic retention time and dissolved oxygen on nutrient removal in a lab-scale anaerobic-anoxic-oxic activated sludge biofilm reactor. Water Sci Technol . 2018; 17; 77(1): 248-59.

Shreve MJ, Brennan RA. Trace organic contaminant removal in six full-scale integrated fixed-film activated sludge (IFAS) systems treating municipal wastewater. Water Res. 2019 Mar 15; 151: 318-31.

Tabraiz S, Hassan S, Abbas A, Nasreen S, Zeeshana M, Fidaa S, et al. Effect of effluent and sludge recirculation ratios on integrated fixed films A2O system nutrients removal efficiency treating sewage. Desalin Water Treat. 2018; 114: 120–7.

Jaafari J, Seyedsalehi M, Safari GH, Arjestan ME, Barzanouni H, Ghadimi S, et al. Simultaneous biological organic matter and nutrient removal in an anaerobic/anoxic/oxic (A2O) moving bed biofilm reactor (MBBR) integrated system. Int J Environ Sci Technol. 2017; 14: 291–304.

Wang C, Liu Y, Lv W, Xia S, Han J, Wang Z, et al. Enhancement of nitrogen removal by supplementing fluidized-carriers into the aerobic tank in a full-scale A2/O system. Sci Total Environ. 2019 Apr 10; 660: 817-25.

Xiao J, Chu S. A novel bamboo fiber biofilm carrier and its utilization in the upgrade of wastewater treatment plant. Desalin Water Treat. 2015; 56(3): 574–82.

Dang HTT, Dinh C V, Nguyen KM, Tran NTH, Pham TT, Narbaitz RM. Loofah Sponges as Bio-Carriers in a Pilot-Scale Integrated Fixed-Film Activated Sludge System for Municipal Wastewater Treatment. Sustain Artic. 2020; 12(11): 4758.

Farrokhi M, Ashrafi D, Roohbakhsh E, Yoonesi A. Hospital Wastewater Treatment by Integrated Fixed Film Activated Sludge, Using Rice Husk as Fixed Media. Adv Life Sci. 2014; 4(3): 178–83.

Zainab A, Meraj S, Liaquat R. Study on Natural Organic Materials as Biofilm Carriers for the Optimization of Anaerobic Digestion. Waste Biomass Valorization. 2020; 11(6): 2521–31.

Kanwar RMA, Khan ZM, Farid HU. Investigation of municipal wastewater treatment by agricultural waste materials in locally designed trickling filter for peri-urban agriculture. Water Supply. 2021; 21(5): 2298–312.

Huang L, Ye J, Xiang H, Jiang J, Wang Y, Li Y. Bioresource Technology. Enhanced nitrogen removal from low C / N wastewater using biodegradable and inert carriers : Performance and microbial shift. Bioresour Technol. 2020; 300: 122658.

Shehab D, durra Al Haddad G, Hadid M. Removal of Suspended Solids Using Pumice Stone in Integrated Fixed Film Activated Sludge Process. Baghdad Sci J. 2021 Mar 10;18(1):0041-0041.

Al-Saade KA, AL-Mammar DE, AL-Ani HN. Using Phragmitesaustralis (Iraqi plant) to remove the Lead (II) Ions form Aqueous solution. Baghdad Sci j. 2017 Mar 5; 14(1): 0148-0148.

Leyva-Díaz JC, Mu˜nío MM, González-López J, Poyatos JM. Anaerobic/anoxic/oxic configuration in hybrid moving bed biofilm reactor-membrane bioreactor for nutrient removal from municipal wastewater. Ecol Eng. 2016; 91: 449–58.

Li J, Peng Y, Zhang L, Liu J, Wang X, Gao R, et al. Quantify the contribution of anammox for enhanced nitrogen removal through metagenomic analysis and mass balance in an anoxic moving bed biofilm reactor. Water Res. 2019 Sep 1; 160: 178-87.

Gao R, Peng Y, Li J, Li X, Zhang Q, Deng L, et al. Nutrients removal from low C/N actual municipal wastewater by partial nitritation/anammox (PN/A) coupling with a step-feed anaerobic-anoxic-oxic ( A/A/O) system. Sci Total Environ. 2021; 799: 149293.

Li J, Peng Y, Zhang L, Gao R, Yang L, Liu Q, et al. Enhanced nitrogen removal assisted by mainstream partial-anammox from real sewage in a continuous flow A2/O reactor. Chem Eng J. 2020; 400: 125893.

Le HT, Jantarat N, Khanitchaidecha W, Ratananikom K, Nakaruk A. Utilization of Waste Materials for Microbial Carrier in Wastewater Treatment. Biomed Res Int. 2016; 2016. 1-6.