Hygienic effects and gas production of plastic bio-digesters under tropical conditions

Vo Thi Yen-Phi, Joachim Clemens, Andrea Rechenburg, Björn Vinneras, Christina Lenßen and Thomas Kistemann (2009). Hygienic effects and gas production of plastic bio-digesters under tropical conditions. Journal of water and health ; vol. 7, no. 4 ; p. 590–596. doi:10.2166/wh.2009.127

Abstract

Plastic plug-flow bio-digesters have been promoted as a good option for improved treatment of manure and wastewater in developing countries although minimal information has been published on their hygienic status. This bench-scale study replicates bio-digester conditions to evaluate the reduction of pathogen and indicator microorganisms at three different hydraulic retention times (HRT) in the anaerobic treatment of pig manures at 30°C for 50 days. Results showed that physicochemical values differed between HRTs. Gas production efficiency was better for longer HRTs. The accumulated sludge at the reactor’s base increased with longer HRT. Phages and bacteria examined were reduced, but none was completely eliminated. Log10 reduction of bacteria ranged from 0.54 to 2.47. Phages ranged from 1.60 to 3.42. The reduction of organisms at HRT = 30 days was about one log10 unit higher than HRT = 15 days and about two log10 units higher than HRT = 3 days. The results indicate that the reduction of tested organisms increases with HRT. However the hygienic quality of the liquid effluent does not meet required quality values for surface and irrigation water. Longer HRTs are recommended to increase gas yield and achieve higher pathogen reduction. More barriers should be applied while handling bio-digester outputs to minimise risks to environmental and human health.

PRoACC: UNESCO-IHE Post-Doctoral Research Programme on Adaptation to Climate Change

The overarching objective of this 18 month project (15 October 2009 – 15 April 2011) is to investigate in an integrated way the many challenges of adapting to climate change from different ‘water perspectives’, and to develop sustainable solutions for a better future water management.

The post-doctoral fellowship programme is part of the UNESCO-IHE Partnership Research Fund (UPaRF) that was established in April 2008, which aims to strengthen research output of the institute in collaboration with its partner institutes.

PRoACC has identified a number of interrelated research topics and intends to provide 7 post-doctoral research fellowships.

The following positions are planned, the project leader of UNESCO-IHE are given in brackets:

On river basin and coastal management issues in the Incomati-Maputo Basin in Southern Africa, four positions related to the following five fields:

• Hydrology: How can a river basin that is vulnerable to climate change adapt to minimize the impacts on hydrology? (Prof. S. Uhlenbrook)
• River morphology: The impact of climate change and adaptation measures on river morphology (Prof. N. Wright)
• Freshwater ecology: The ecological impacts of climate change in the river and the formulation of environmental flow requirements (Prof. J. O’Keeffe)
• Coastal engineering: The processes and physical changes of large and small scale morphodynamics of flood tide deltas and tidal inlets (Prof. D. Roelvink)
• Hydroinformatics: Downscaling of climate change scenarios and risk management modelling of vulnerabilities to climate change (Prof. D. Solomatine)

On urban water management issues in yet to be decided locations, two positions related to the following three fields:

• Waste water management: Design of wastewater systems which are more flexible to varying demands in terms of quality and quantity, both between years and between seasons of the year, taking into account the notion – from wastewater discharge to agricultural fields (Prof. P. Lens)
• Urban drainage: Design and modelling techniques that can make urban drainage systems more resilient and flexible over a larger range of future weather/climatic events. (Prof. D. Brdjanovic)
• Water supply engineering: Robust, natural water treatment approaches to deal with climate variability: bank filtration, aquifer recharge and recovery, and soil aquifer treatment (Prof. G. Amy)

On institutional issues (location to be decided) one position related to:

• Institutions for adaptation: How to assess the adaptive capacity of institutions, and how can the ability of social actors to deal with climate change be enhanced (Prof. J. Gupta)

The concept project descriptions and further information about PROACC are available at www.unesco-ihe.org/PRoACC.

Contact: Dr. Rosh Ranasinghe, programme coordinator, r.ranasinghe@unesco-ihe.org

South Africa: Joburg Water, University Agree to expand research expertise

Johannesburg Water (JU) and University of Johannesburg (UJ) have signed a Memorandum of Understanding [on collaboration] on water and sanitation research and development projects [...] specifically in water nanotechnologies, water purification, waste water treatment and innovation in water analysis.

Mr Jones Mnisi, Acting Chief Operation Officer, Johannesburg Water (JW). and Prof Derek van der Merwe, Pro Vice-Chancellor and Vice-Principal, University of Johannersburg (UJ) at the signing of the Memorandum of Understanding (MoU) at Johannesburg Water on Friday, 16 January 2009. Photo: UJ.

Read more: Gabi Khumalo, Bua News / allAfrica.com, 16 Jan 2009 ; Johannesburg Water, 16 Jan 2009

Water lettuce ‘mops up toxic metals’

Pistia stratiotes, or the common water lettuce found in most tropical areas, can mop up toxic metals from municipal sludge. Indian scientists report the plant’s fronds and roots accumulate substantial amounts of metals. The plant fights any damage to itself by increasing antioxidant activity and levels of carotenes.

Anamika Tewari, A. … [et al.] (2008). Amelioration of municipal sludge by Pistia stratiotes L. : role of antioxidant enzymes in detoxification of metals
Bioresource Technology, In Press, Corrected Proof, Available online 21 May 2008. doi:10.1016/j.biortech.2008.04.018