Tag Archives: sewage sludge

Infectious Risks Associated with Land Application of Sewage Sludge

Env. Sci & Tech, July 2011

Toward a Consensus View on the Infectious Risks Associated with Land Application of Sewage Sludge

Link to abstract, author email address

Emily Viau, et al.

The science linking processed sewage sludge (biosolids) land application with human health has improved in the last ten years. The goal of this review is to develop a consensus view on the human health impacts associated with land-applying biosolids. Pre-existing risk studies are integrated with recent advances in biosolids pathogen exposure science and risk analysis. Other than accidental direct ingestion, the highest public risks of infection from land application are associated with airborne exposure. Multiple, independent risk assessments for enteroviruses similarly estimate the yearly probabilities of infection near 10–4. However, the inclusion of other emerging pathogens, specifically norovirus, increases this yearly infectious risk by over 2 orders of magnitude. Quantitative microbial risk assessment for biosolids exposure more effectively operates as a tool for analyzing how exposure can be reduced rather than being used to assess “safety”. Such analysis demonstrates that the tradition of monitoring pathogen quality by Salmonella spp. and enterovirus content underestimates the infectious risk to the public, and that a rigorous biosolids pathogen treatment process, rather than extending community separation distances, is the most efficient method for reducing pathogen exposure and infectious risk.

US-Ghana team gets Gates Foundation grant to transform human waste into energy

A US-Ghanaian team has been awarded US$ 1.5 million from the Bill and Melinda Gates Foundation to develop a biorefinery that will convert fecal sludge to biodiesel and methane.

Prof. Kartik Chandran. Photo: Columbia University

Kartik Chandran, an associate professor of Earth and Environmental Engineering at Columbia Engineering is leading the team that includes Ashley Murray, founder and director of Waste Enterprisers, and Moses Mensah, a Chemical Engineering professor at Kwame Nkrumah University of Science and Technology. Chandran may involve the Columbia University Engineers without Borders Ghana team, for whom he acts as faculty advisor, as well.

Chandran and his team aim to develop a bioprocess technology to convert the organic compounds present in fecal sludge to biodiesel and methane, two potent sources of energy, and thus convert a waste-processing facility into a biorefinery. The biorefinery will not only be an economical source of fuel, but, by minimizing discharge of fecal sludge into local water bodies, it will also contribute to improved human health and sanitation. Chandran says that potential outcomes of his work will also include integrating the bioprocess technology component into a social enterprise business model that will further promote widespread implementation of this approach and technology across the globe, especially in developing economies.

Earlier Waste Enterprisers conducted an exploratory study, funded by the Gates Foundation, to identify promising fecal sludge reuse and management options for  Greater Accra, Ghana. Their study incorporated  detailed analyses of emerging energy-related reuse options. Waste Enterprisers is one of the partners in a European Water Initiative ERA-NET – SPLASH project on “Faecal Management Enterprises (FaME)” in Ghana, Senegal, and Uganda. One of project activities is to demonstrate the technical and financial viability of using faecal sludge as a fuel in cement manufacturing (and other industrial processes).

Dr. Ashley Murray, founder Waste Enterprisers, Ghana and a 2011 recipient of a National Geographic's Emerging Explorers Program award. Photo: Matthew Muspratt

Since about two years the Gates Foundation has shifted its focus from water and hygiene to sanitation. While the Foundation continues to provide limited funding to promising clean water and hygiene solutions, its main grantmaking will go to three areas: ending open defecation; investment in sanitation tools and technologies; and policy and advocacy.

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Source: Columbia University, 01 Jun 2011

UK: ‘Poo-powered’ car seen on the streets of Bristol

A “poo-powered” VW Beetle has taken to the streets of Bristol in an attempt to encourage sustainable motoring.

Photo: Geneco

The Bio-Bug runs on processed methane gas generated as part of the raw sewage treatment process.

Wessex Water engineers estimate the yearly waste from 70 average households would generate enough gas to run the car for 10,000 miles (16,100km).

Despite being powered by fuel created from sewage, the car does not smell unpleasant.

“It performs like a normal car – you wouldn’t know it was powered by biogas,” a company spokesman said.

‘Surplus gas’

To use biogas as vehicle fuel without affecting vehicle performance or reliability the gas needs to be treated to remove the carbon dioxide content.

GENeco, part of Wessex Water, imported specialist “cleaning” equipment to treat the raw methane generated at the sewage treatment works in Avonmouth.

The spokesman added: Our site has been producing biogas for many years which we use to generate electricity to power the site and export to the National Grid.

“With the surplus gas we had available we wanted to put it to good use in a sustainable and efficient way.

“We decided to power a vehicle on the gas offering a sustainable alternative to using fossil fuels which we so heavily rely on in the UK.”

Read more about the Bio-Bug on the Geneco web site.

Source: BBC, 05 Aug 2010

China, Wuhan: ADB supports wastewater and lake management project

The Asian Development Bank (ADB) is supporting an urban environmental initiative in Wuhan municipality in the People’s Republic of China (PRC) that it says could be a model for sustainable management of wastewater sludge in the country.

The ADB has approved a $100 million loan for the Wuhan Urban Environmental Improvement Project that will involve the treatment and disposal of sewage sludge, and the rehabilitation of polluted lakes and water channels, benefiting up to 3 million urban residents in the municipality.

Wuhan, the capital of Hubei Province with a population of nearly 9 million people, is successfully treating most of its wastewater through the support of previous ADB assistance. However, the huge amount of sewage sludge generated by the treatment plants – estimated at 657 tons a day – poses growing environmental and health hazards.

The project will incorporate a number of innovative and integrated measures designed to improve the environment and support the government for a more sustainable urban development master plan.

The project will introduce a decentralized approach by building small on-site sludge units integrated with the city master plan. Sludge from Wuhan’s wastewater plants will be dried and treated using biogas from an ADB-financed wastewater facility and steam from a thermal power plant. In addition, the dried sludge will be used as a soil conditioner and filler for building construction materials, supporting the PRC’s push to create sustainable local economies that reduce, reuse and recycle waste. The project will advocate for beneficiary sludge treatment and utilization.

[...]

The project will also help restore Wuhan’s polluted lakes and water channels. Sediment dredging and slope protection work will be carried out, while flood control gates and a water pumping station will also be built. A storm water treatment system will be established for Yangchun Lake, artificial wetlands will be created, and lakes will be planted with aquatic plants.

[...]

Wuhan’s lakes and rivers, which make up 25% of its urban area, have become seriously polluted by agricultural activity and urban construction, with just 38 of 100 lakes in the mid-20th century still in existence.

An environmental public awareness campaign targeted at lakeside businesses, communities and schoolchildren will be carried out, while training and other support will be given for wastewater and sludge treatment operation and maintenance.

ADB’s assistance makes up nearly 20% of the total project cost of about $501.8 million. The Wuhan Municipal Government is providing counterpart funds equivalent to $125.4 million, while the Agricultural Bank of China is supplying a 10-year loan of $276.3 million. The municipal government is the executing agency for the project which is expected to be completed by December 2014.

Source: ADB, 01 Jul 2010

Waste Water Treatment Plant Mud Used As ‘green’ Fuel

Scientists have shown that using mud from waste water treatment plants as a partial alternative fuel can enable cement factories to reduce their CO2 emissions and comply with the Kyoto Protocol, as well as posing no risk to human health and being profitable. These are the results of an environmental impact assessment.

Dependency on oil and coal could be coming to an end. Researchers from the Rovira i Virgili University (URV) have analysed the environmental and human health impacts of an alternative fuel that solves various problems simultaneously. This is the solid waste from the water treatment plants of large cities.

The scientists have carried out the first study into this method at a cement plant in Vallcarca (Catalonia), which has been producing cement for more than 100 years, and they confirm in the latest issue of the journal Environmental Science and Pollution Research that it is “the best option for getting rid of mud that would have had to be dumped elsewhere, while also powering the plant”.

[...] Up to 20% of the fossil fuel energy used at the Catalan plant has now been substituted for the fuel from waste water treatment plant mud.

One of the most important issues for the URV scientists is the reduction in environmental impact, and consequently the health risks for people living near the plants. The experiment with the mud has led to a 140,000 tonne reduction in CO2 emissions between 2003 and 2006, and will have limited the potential deaths from exposure to chemical pollutants. In addition, the study shows that using this green fuel would reduce the cancer rate by 4.56 per million inhabitants.

The researchers say it is essential to carry out separate studies for each plant because “we still don’t know whether this will be positive for the whole cement industry”, according to Domingo. However, if the conditions are right, using mud from waste water treatment plants in cement factories is “a very good solution”, he concludes

Source: Plataforma SINC, ScienceDaily, 23 Jun 2009