Wastewater management in small towns – understanding the failure of small treatment plants in Bolivia

Abstract

Wastewater management in developing countries is a challenge, especially in small towns with rapid population growth. This study aims at assessing the performance and management of five treatment plants (TPs) in rural areas of Cochabamba, Bolivia. Pollutants' concentrations, wastewater flows, hydraulic and organic loads and hydraulic retention times were determined in three small treatment plants (2000-10,000 population equivalent [p.e.]; flow > 432 m/d) and two very small treatment plants (<2000 p.e.; flow < 432 m/d). The performance assessment was based on operational parameters, treatment efficiency and effluent quality. Management data were collected through semi-structured interviews with managers of local water associations. The results support that the poor performance of the TPs is due to lack of operational expertise and financial resources for adequate operation and maintenance (O&M). Additionally, effective treatment was affected by the type of technology used and whether the plant design included plans for O&M with available resources. This study contributes to a better understanding of actual operating conditions of wastewater TPs in small towns, thus providing needed information regarding technology selection, design, implementation and operation.

Impact of treatment plant management on human health and ecological risks from wastewater irrigation in developing countries – case studies from Cochabamba, Bolivia

“…The O&M of WWTPs was scored based on five indicators (Table 2): (i) required level and availability of technical expertise needed for optimal O&M of the specific WWTP, (ii) required O&M activities and frequency in pre-treatment, which is critical for following processes to work optimally, (iii) required regular O&M activities to ensure WWTP functionality, (iv) long-term maintenance activities in the main process units, e.g. important repairs or replacements and (v) a monitoring system that can support optimal O&M, since lack of monitoring is often a key issue in small-scale WWTPs (Cossio et al 2017).…”

“…Cases 4-I and 5-I, with Imhoff tanks, performed poorly in all management criteria. They are designed to reduce the concentration of TSS by up to 50% and BOD by up to 35% (Cossio et al 2017), but this not occurring, probably due to the lack of O&M activities. The Imhoff tank technology is also not sufficient to meet health-based targets for reuse of effluents in agriculture.…”

“…There is extensive literature about available treatment processes with high removal efficiencies of both pathogens and nutrients from wastewater, but comparison and selection of such upgrades were outside the scope of this study. However, the local resources available in terms of technical expertise and financial resources should be part of the decision-making processes on WWTP upgrading, so that the chosen technology can be operated at its full potential (Cossio et al 2017). It is also important that the treatment process is designed with the safe use of the effluent for irrigation purposes as a design criterion.…”

“…However, both lack of financial and technical resources in developing countries are major challenges for implementing wastewater treatment strategies, monitoring to identify insufficient treatment plants and hampering sustainable operation (Massoud et al 2009;Qadir et al 2010;Noyola et al 2012). The major issues affecting sustainable functioning of small-scale wastewater treatment plants (WWTPs) in developing countries are inappropriate design or selection of technology (Bdour et al 2007;Brissaud 2007;Massoud et al 2009;Mara 2013), poor operation and maintenance (Singhirunnusorn and Stenstrom 2009;Noyola et al 2012), lack of technical expertise (Ujang and Buckley 2002;Noyola et al 2012) and lack of monitoring (Massoud et al 2009;Cossio et al 2017). Recognizing the complexity of the situation, the WHO has proposed an approach in which several risk management alternatives (conventional and non-conventional) are compared in terms of risk outcomes and feasibility of their implementation (WHO 2006).…”

Design and Performance Evaluation of Decentralized Wastewater Treatment and Reuse System for Urban and Rural places

“…India is experiencing an exponential growth in last few decades, in the population as well as in economic / industrial growth. Due to the above scenarios the available centralized treatment facilities are showing an abysmal performance and hence the ground water and surface water sources are highly contaminated (Cossio et al, 2018).…”