International Journal of Engineering and Technology Volume 3 No. 2, February, 2013 ISSN: 2049-3444 © 2013 – IJET Publications UK. All rights reserved. 189 Evaluation of the Influence of Reactor Design on the Treatment Performance of an Optimized Pilot-Scale Waste Stabilization Pond David O. Olukanni Department of Civil Engineering, Covenant University, P.M.B. 1023, Ota, Ogun State, Nigeria ABSTRACT Waste stabilization pond (WSP) is globally one of the most popular wastewater treatment options due to its high efficiency and low cost. A field scale prototype was designed and scaled down to a pilot-scale model using dimensional analysis in the development of the foot print size. Pilot-scale reactors were built with the specifications produced from literature suggested reactor geometric configurations and experimental study was conducted to evaluate the performance of optimized pilot-scale WSP configurations. The optimized pilot scale WSPs consisted of an anaerobic, facultative, and a maturation stage with varying baffle orientation, length to width ratio, and depth. Comparisons were made on the optimized pilot-scale WSP reactors. The removal performance of the experimental test was based on a number of parameters (Faecal coliform, pH, TDS, and Conductivity). Results showed that the significantly lower cost design displayed slightly better removal performance compared to other WSP design developed from literature data. This paper covers a relevant subject within the field of waste stabilization ponds, namely the representation of the influence of reactor design on the treatment performance of WSP. Keywords: Waste Stabilization Pond, Reactor design, Pond-configuration, Performance and Cost. 1. INTRODUCTION The construction cost for a standard wastewater treatment plant has been a major barrier for the implementation of modern technologies by local authorities in many African nations (Agunwamba, 1994 and 2001b; Olukanni and Aremu, 2008, Olukanni and Ducoste, 2011). In addition, these technologies require considerable technical expertise, which is often not available in developing nations to successfully operate these treatment facilities. Consequently, developing nations are unable to incorporate these technologies as part of a wastewater treatment master plan. It is therefore imperative to develop treatment systems that are economical and sustainable. Among the current processes used for wastewater treatment, WSPs have been identified and consistently selected as the unit process of choice for wastewater treatment in developing nations due to their low cost and efficient operation in tropical regions (Mara, 1997; Agunwamba, 2001a; 2004; Abbas et al., 2006; Kaya et al., 2007; Naddafi et al., 2009; Olukanni and Ducoste, 2011). Agunwamba (1994), Babu et al (2010) and Mara (2004) describe a WSP as a chemical reactor used for the reduction of solids, organic matter, and pathogenic organisms. The WSP system usually consists of a series of continuous flow anaerobic, facultative, and maturation ponds. The anaerobic pond is designed for eliminating suspended solids and some of the soluble organic matter while the facultative pond is designed for further removal of the residual organic matter through the activity of algae and heterotrophic bacteria. The final stage of pathogens and nutrients removal takes place in the maturation pond (Olukanni and Ducoste, 2011; Babu, et al., 2010). WSPs are most suited for tropical and subtropical countries since the sunlight irradiance and ambient temperature are key factors for the WSP process efficiency (Mara, 2004; Mara 2001; Mara and Pearson, 1998). However, the application of a WSP system is limited by its large area requirement (Agunwamba, 1994 and 2001a). In addition, no rigorous experimental assessment of a WSP system that account for cost along with treatment efficiency has been performed (Olukanni and Ducoste, 2011). The goal of any WSP system designer would be to optimize pond design by minimizing cost and land required while maintaining treatment effluent standards. The treatment of wastewater through WSPs has been an important research area over the past three decades (Olukanni and Ducoste 2011; Agunwamba, 2001a; Mara, 2004). Oke, et al (2006) assessed the physical and engineering properties of a WSP system in Ahmadu Bello University (ABU), Zaria (Nigeria). The WSP system consisted of facultative and maturation ponds in series with hydraulic retention time of 6- and 24-days, hydraulic loading 10.2 and 15.34 (m 3 /m 2 .d) and BOD loading of 0.75 and 4.59 (kg/ha.d), respectively. Influent and effluent wastewater qualities were monitored from their system for one year. Oke et al.’s results revealed an average fecal coliform removal efficiency of 99% and an average reduction in suspended solids by 66%. The ammonia and phosphate concentrations of the raw influent were reduced