Evaluation of a domestic wastewater treatment plant at an intermediate city in Cochabamba, Bolivia

Abstract

This study aims to determine the seasonal variability in the performance of a medium size population wastewater treatment plant (WWTP) in Bolivia. The semi-arid area where the WWTP is located is characterized as agricultural land, with an annual rainfall of 500 mm and a mean temperature of 17 °C. The WWTP is built up of five modules, each one comprising two treatment trains composed of an upflow anaerobic sludge blanket (UASB) reactor and horizontal gravel filter. The performance of the full process has been determined based on water quantity and quality. Seven monitoring campaigns of chemical and physical wastewater characteristics were performed from March to December 2017. The measured effluent showed average removal efficiencies of 83 ± 8% and 37 ± 60% for total chemical oxygen demand (COD) and total suspended solids (TSS), respectively. The treatment system has proven to be efficient to remove organic matter and TSS, despite the occurrence of high COD and total solids (TS) influent concentrations, the accumulation of solids at all the processes and the variability of flow and temperature inside the UASB reactors. In order to improve further this efficiency, it is recommended to implement a primary sedimentation unit as a pretreatment for the UASB system that would help to homogenize both the flow and the quality of the influent.

Small-Scale Operation of an Integrated Anaerobic Baffled Reactor and Biofilter: Factors Affecting Its Performance

“…9) is noticed. Similar behavior was reported by Saavedra et al (2019) for a UASB-HGF configuration located in the same geographical zone and under similar climatic conditions.…”

“…Anaerobic reactors combined with biofilters generally show adequate performance in wastewater treatment. For example, Saavedra et al (2019) reported the performance of a WWTP comprising UASB reactors followed by biofilters located very close to Tolata's WWTP. Under similar climatic conditions, they reported TCOD removals at the UASB between 35 and 50%, affected mainly by solid biomass washout.…”

Up-Flow Anaerobic Sludge Blanket (UASB) Technology for Energy Recovery: A Review on State-of-the-Art and Recent Technological Advances

“…Regarding process efficiency, a long-term analysis of seven full-scale treatment plants operating at ambient temperature in India highlighted that UASB reactor, followed by conventional aerobic processes, failed to comply with required effluent standards, while UASB reactor, followed by a DHS system, allowed to obtain high COD, BOD, total suspended solids (TSS), ammonia and phosphate abatements [ 106 ] and thus could be considered a more environmentally friendly solution. Similarly, full-scale UASB treatment at ambient temperature (mean 17 °C) was reported in the work in [ 107 ] in Bolivia, with moderate COD and TSS abatements, even if biogas valorization was not done [ 106 ]. This proves that an advancement is needed in developing countries to efficiently exploit the high-energy content of biogas.…”