Lettinga Associates Foundation LeAF

Wageningen, Netherlands

Lettinga Associates Foundation LeAF

Wageningen, Netherlands
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Yaya-Beas R.-E.,Peruvian National University of Engineering | Yaya-Beas R.-E.,Wageningen University | Cadillo-La-Torre E.-A.,Peruvian National University of Engineering | Kujawa-Roeleveld K.,Wageningen University | And 5 more authors.
Water Research | Year: 2016

This work studied the anaerobic sludge filtration capacity for pathogens reduction in a 29 L and 1.65 m height lab-scale UASB reactor treating domestic wastewater at low temperatures in the city of Puno (Peru). The anaerobic sludge filtration capacity was performed applying upflow velocities of 0.12, 0.14, 0.16, 0.20, 0.27 and 0.41 m/h. Results show that the HE removal varied between 89 and 95% and the most common specie was Ascaris lumbricoides. Faecal coliform and Escherichia coli removal varied in the range of 0.9-2.1 and 0.8-1.6 log10 respectively. Likely related to the low operational temperatures, the total COD removal varied between 37 and 62%. The best performance in terms of removal of HE, total COD and turbidity was obtained at the lowest upflow velocity of 0.12 m/h. In order to meet WHO standards for water reuse a post-treatment unit will be required to polish the effluent. © 2015 Elsevier Ltd.


Tas N.,Wageningen University | Tas N.,VU University Amsterdam | van Eekert M.H.A.,Wageningen University | van Eekert M.H.A.,Lettinga Associates Foundation LeAF | And 4 more authors.
Applied and Environmental Microbiology | Year: 2011

The diffuse pollution by chlorinated organic compounds in river basins is a concern, due to their potential adverse effects on human health and the environment. Organohalides, like hexachlorobenzene (HCB), are recalcitrant to aerobic microbial degradation, and "Dehalococcoides" spp. are the only known microorganisms capable of anaerobic transformation of these compounds coupled to their growth. In this study, sediments from four European rivers were studied in order to determine their HCB dechlorination capacities and the role of Dehalococcoides spp. in this process. Only a weak correlation was observed between Dehalococcoides species abundance and HCB transformation rates from different locations. In one of these locations, in the Ebro River sediment, HCB dechlorination could be linked to Dehalococcoides species growth and activity by 16S rRNAbased molecular methods. Furthermore, HCB dechlorination activity in this sediment was found over the full range of ambient temperatures that this sediment can be exposed to during different seasons throughout the year. The sediment contained several reductive dehalogenase (rdh) genes, and analysis of their transcription revealed the dominance of cbrA, previously shown to encode a trichlorobenzene reductive dehalogenase. This study investigated the role of Dehalococcoides spp. in HCB dechlorination in river sediments and evaluated if the current knowledge of rdh genes could be used to assess HCB bioremediation potential. © 2011, American Society for Microbiology.


Yaya-Beas R.-E.,Peruvian National University of Engineering | Yaya-Beas R.-E.,Wageningen University | Ayala-Limaylla C.,Peruvian National University of Engineering | Kujawa-Roeleveld K.,Wageningen University | And 5 more authors.
Water (Switzerland) | Year: 2015

This research was conducted to study the anaerobic sludge filtration capacity regarding helminth egg removal in upflow anaerobic sludge blanket (UASB) reactors. Two 25 L lab-scale UASB reactors were operated at an ambient temperature which varied between 17.1 and 28.6 °C. Ascaris suum egg was selected as the model egg considering its similarity in terms of size and morphology to Ascaris lumbricoides, a human pathogen. Ascaris suum eggs were obtained from female parasites of infected pigs. The anaerobic sludge filtration capacity was performed applying upflow velocities between 0.09 and 0.68 m·h-1. Three sludge bed heights in the range of 0.30-0.40 m, 0.50-0.60 m and 0.60-0.70 m were applied. These sludge bed heights corresponded to 19%-25%, 31%-38% and 38%-44% of the total reactor height, respectively. Under the mentioned conditions, the average helminth egg removal efficiency was reciprocally correlated to the imposed upflow velocity. The studied lab-scale reactors reported an average helminth egg removal between 34%-100%, 30%-91% and 34%-56%, when the sludge bed in the UASB reactorwas 19%-25%, 31%-38% and 38%-44% of the total reactor height, respectively. The decreased filtration capacity at increasing sludge bed heights might be likely related to biogas production and channeling formation. The average helminth egg removal efficiency in the control experiments performed without any sludge bed, by plain sedimentation, varied between 44% and 66%. © 2015 by the authors.


Naranjo A.,Lettinga Associates Foundation LeAF | Naranjo A.,Landustrie Sneek BV | Naranjo A.,Wageningen University | Castellano D.,Lettinga Associates Foundation LeAF | And 6 more authors.
Water Science and Technology | Year: 2010

Pook se Bos informal settlement and the Cape Town Water & Sanitation Services Department are partnering on an urban sanitation project with a Dutch Consortium consisting of Lettinga Associates Foundation (LeAF), Landustrie Sneek and Vitens-Evides International. The aim of the project is to improve the basic sanitation services provided in informal settlements through the implementation of the MobiSan approach. The approach consists of a communal Urine-Diversion and Dehydration Toilet (UDDT) built in a former sea shipping container. The system is independent of water, electricity or sewerage connection and it is maintained by full-time community caretakers who also act as hygiene promoters. The project seeks to link sanitation services with hygiene promotion in informal settlements while enhancing user satisfaction and reducing costs in providing basic sanitation services. This paper describes the preliminary experiences and lessons learnt during the implementation and evaluation of the MobiSan prototype and discusses its potential for replication. The MobiSan has proved to be an appropriate option by means of dealing successfully with shallow groundwater table, land availability and high settlement densities. In addition it has been demonstrated to be cost-competitive in terms of operating cost compared to chemical toilets. © IWA Publishing 2010.

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