Investigation of TC and TSS Removal Efficiencies at Ahvaz West WTP Effluent Using the Land‒plant Treatment Process

Document Type : Research Paper


1 Assoc. Prof. of Environmental Health Engineering and Environmental Technohogies Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz,Iran

2 MSc Student of Environmental Health Engineering, School of Public Health, ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran

3 Ass. Prof. Agricultural and Natural Resources Research Center of Khuzestan, Ahvaz, Iran

4 Ass. Prof. of Epidemiology and Statistic Department, School of Public Health, Ahvaz Jundishapour University of Medical Sciences, Ahvaz, Iran


Although the conventional (primary and secondary) treatment processes are known to remove up to 95–99% of some micro-organisms, they do not provide adequate treatment to make the effluent suitable for direct reuse, mainly due to the presence of high concentrations of pathogenic microorganisms. Obtaining reusable effluents, therefore, requires the use of processes that can be justified both technical and economic grounds. One such indigenous, low cost option is the land-plant process that can be used for advanced wastewater treatment. It is the objective of the present study to determine the efficiency of the local soil in Ahvaz and that of the vetiver plant in reducing the microbial load in the effluent from municipal wastewater treatment plants. A pilot study was thus carried out including three Lysimeters installed in West Ahvaz Wastewater Treatment Plant. Local soil was used in one Lysimeter, local soil with vetiver plant in the second one, and an artificial assortment of soil comprising local soil, silica sand (0.5-1mm), and sand (15-30mm) in the third. In addition, the effluent from the secondary settling outlet at the WTP was transferred by pumping at the three filtration rates of 0.2, 0.6, and 1 ml/min into the system with three replications for each rate and samples were collected from both inlet and outlet flows. The average removal efficiencies of Total Suspended Solids (TSS) and Total Coliform (TC) in the effluent from the three Lysimeters with local soil with vetiver, local soil without vetiver, and artificial soil assortment for the filtration rate of 0.2 ml/min were: 67.75% and 99.7%, 58.33% and 99.6%, and 56.25% and 99.5%, respectively. For a filtration rate of 0.6 ml/min, these values were: 53.33% and 98.93%, 48.8 and 98.77%, and 47.68% and 98.64%. Finally, the values obtained for a filtration rate of 0.6 ml/min were: 50% and 93.96%, 46.42 and 91.34%, and 44/04% and 88/81%, respectively. The results from the study showed that the Lysimeter with local soil and the vetiver plant recorded the best removal efficiency for a filtration of 0.2 ml/min. Thus, it may be concluded that the land-plant system as an advanced treatment process is capable of producing effluents that meet discharge quality permit limits and therefore, it is an economical process using the advantages of advanced treatment if enough and available lands possible.


Main Subjects

1. Amin, M.M., Hashemi, H., Ebrahimi, A., Bina B., Movahhedian Attar H., Jaberi A., Saffari, H., and Mousavian, Z. (2010). “Using combined processes of filtration and ultraviolet irradiation for effluent disinfection of Isfahan north wastewater treatment plant in pilot scale.” J. of Water and Wastewater, 22-2 (78), 71-77. (In Persian)
2. Sharafi, K., Drayat, J., Khodadadi, T., Asadi, F., and Poureshg, Y. (2011). “The efficiency comparison of constructed wetland and conventional activated sludge on removal of cysts and parasitic eggs-case study: Ghasr -e-Shirin and Kermanshah wastewater treatment plants.” Health Journal of Ardabil, 2(3),
7-13. (In Persian).
3. Koivunen, J., Siitonen, A., and Heinonen-Tanski, H. (2003). “Elimination of enteric bacteria in biological-chemical wastewater treatment and tertiary filtration units.” Water Res., 37(3), 690-698.
4. Lazarova, V.P, Savoye, M.L., Janex, E.R., Blatchley, M., and Pommepuy, M. (1999). “Advanced wastewater disinfection technologies: State of the art and perspectives.” Wat. Sci. Technol., 40(4-5), 203-213.
5. Mbuligwe, S.E., Kaseva, M.E, and Kassenga, G.R. (2011). “Applicability of engineered wetland systems for wastewater treatment in Tanzania – A review.” The Open environmental Engineering Journal, 4, 18-31.
6. Tchobanoglous, G., Burton, F.L. (2005). Wastewater engineering: Treatment, disposal and reuse, 3rd Ed., Metcalf and Eddy, Pub., McGraw-Hill. Inc., New York.
7. Ou, Z., Chang, S., Gao, Z., Sun T., and et al. (2005). “Paddy rice slow-rate land treatment systems hydraulic balances and results of 4 years operation.” Water Research, 26,1487-1494.
8. Ahvaz Water and Wastewater Company. (2005). Operation and maintenance guideline for Ahvaz west wastewater treatment plant, Rayab Consulting Engineers Department of Ministry Energy. 6. (In Persian).
9. Rouyanian Firouz, Z., Takdastan, A., Jaafarzadeh Haghighifard, N., and Sayyad, G.A. (2011). “Feasibility of land treatment that removal of nitrogen and phosphor of chonaibeh waste water treatment plant (Ahvaz). Asian J. Research Chem., 4(4), 597-601.
10. Poorkazem, E. (2006). “Utilization of vetiver grass at water and soil conservation projects in Thailand.” J. of Jahad, 275, 322-342. (In Persian).
11. Truong, P., Van, T.T., and Pinners, E. (2006). Vetiver system application: Technical reference manual, Geotechnical Engineer of Thailand.
12. APHA. (1999). Standard methods for the examination of water and wastewater, 19th Ed., American Public Health Association, Washington, DC.
13. Wen, C.G., Chen, T.H., Hsu, F.H., Lu, C.H., Lin, J.B., Chang, C.H., Chang, S.P., and Lee, C.S. (2007). “A high loading overland flow system: Impacts on soil characteristics, grass constituents, yields and nutrient removal.” Chemosphere, 67, 1588-1600.
14. Taebi, A., and Droste, R.L. (2008). “Performance of an overland flow system for advanced treatment of wastewater plant effluent.” J. of Environmental Management, 88, 688-696.
15. Yousefi, Z., Hoseini, S.M., Mohamadpur Tahamtan, R.A., and Zazouli, M.A. (2013). “Performance evaluation of artificial wetland subsurface with horizontal flow in wastewater treatment.” J. Mazandaran Univ. Med. Sci., 23(99), 12-25.(In Persian)
16. Najafi, P. (2008). “A study on  Microbial contamination of municipal wastewater irrigation of grass.” Environmental Study, 33(44), 27-32. (In Persian)
17. Khazaei, M., Nabizadeh, R., Rahimi, T., and Roshany, M. (2010). “A study on coliform removal from aerated lagoon effluent by horizontal roughingfilter (HRF).” 12th Conference of Environmental Health, Shahid Beheshti University of Medical Sciences, Tehran, 169-180. (In Persian)
18. Shahi, D.H., Ebrahimi, A., Eslami, H., Ayatollahi, S., and Dashty, N. (2012). “Efficiency of straw plants in removal of indicator pathogens from sub surface flow constructed wetlands of municipal wastewater in Yazd, Iran.” Health and Development, 2, 147-155. (In Persian)
19. Ulrich, H., Klaus, D., Irmgard, F., Annette, H., JuanL, P., and Regine, S. (2005). “Microbiological investigations for sanitary assessment of wastewater treated in constructed wetlands.” Water Res, 39(20), 4849-4858.
20. Spieles, D.J., and Mitsch, W.J. (2007). “The effects of season and hydrologic and chemical loading on nitrate retention in constructed wetlands: A comparison of low- and high-nutrient riverine systems.” Ecol. Eng., 14(1-2), 77-91.
21. Vice Presidency For Strategic Planning and Supervision. (2010). Environmental criteria of treated waste water and return flow reuse in Iran, Tehran. (In Persian)