Scientists at the University of Manchester in England have invented a new device which remotely monitors bad odours and methane gases at waste landfill and water treatment sites.

The device, which works like an electronic nose, could be the solution many communities and waste management companies, who regularly encounter problems with bad odours and air pollution, are searching for.

The 20.9m tonnes (72percent) of household of waste produced in Britain is disposed of in landfill sites. There are currently over 4000 licensed sites in the UK. Eightypercent of the population live within 2km of a site. Methane gas and odours, which contribute to global warming, are produced by decomposing waste.

Currently there is no other instrumentation sensitive enough to monitor low concentrations of odours and gases on these sites. Gases and odours are analysed manually using handheld detectors and by panels of volunteers asked to smell samples of air.

The new device has four sensors which analyse the composition of gases in the air (Fig.1). Air is sucked into the device at regular intervals and then profiled. The chemical profile of the air is then sent in real-time via a built-in GPS modem to a remote computer. Based on the concentration of various chemicals, the system is able to determine whether the methane gases or odours have reached an unacceptable level. The air is then filtered before being expelled back into the atmosphere.

Professor Krishna Persaud, who has developed the device, said: “Current methods mean odour and gas levels are only monitored on a weekly basis. In that time bad odours can build up. What this device offers is the ability to monitor these levels in real-time, enabling waste companies to act before levels reach an unacceptable level (Fig.2).

Ultimately, this device has the potential to create a much healthier environment which will benefit both local communities and waste management companies by alerting them to the build up of bad odours and enabling them to ensure monitor methane emissions remain at a safe level.”

Developed in collaboration with the Silsoe Research Institute, the device has already been successfully tested at the Brookhurst Wood waste landfill site near Gatwick airport. Five of the devices have been positioned around the perimeter of the site since May 2005. Professor Persaud is also working with a major water company to monitor foreign chemicals and materials in water which is processed through water treatment plants.

Peat absorbs oil

Oil spills are always difficult to handle and this is particularly true when they occur on water. The oil film spreads out quickly, often over very large distances, and is very difficult to collect. A thick film can be removed by sea bulldozers which scrape it off the surface of the water. As for a thin film, which produces iridescent spots, this is practically impossible to eliminate. And while a film only microns thick may seem relatively harmless, it will reduce the oxygen present in the water and threaten any life there.

An ideal solution to this problem would be a sorbent capable of soaking up oil-based products, but which itself did not contaminate the environment and which could turn hydrocarbons into something harmless.

Now three Russian institutes believe they have achieved this. Working together, the Snezhinsk All-Russian Scientific Research Institute of Technical Physics, the Novosibirsk State Research Centre and the Syktyvkar Institute of Biology – with financial support from the International Science and Technology Centre (ISTC) – have created a sorbent that meets these requirements.

The sorbent is based on peat – one of the most widespread materials in Russia, particularly in the North. First, the peat has to be heated to a specified temperature that renders it so porous that it can absorb several times its own weight in oil.

However, there is a significant difficulty in working with peat. As a sorbent it is very light and extremely hard to disperse evenly across a large area.

This problem has been solved by engineers from Snezhinsk. They have made special dispensers of different sizes, ranging from a shoulder-carried option resembling a garden sprayer, to an industrial unit that can be attached to a fire tender or a motor launch.

As the sorbent is hydrophobic, it remains afloat for several weeks after saturation with oil, making it simple to collect mechanically.

However, this is not the end of the story. Biologists from Syktyvkar and Novosibirsk have developed both microfungi that decompose oil and technology to distribute them thoughout the peat sorbent. Field trials carried out at the Usinsky oil field have found that the microorganisms within the biosorbent are capable of decomposing the oil once it has been absorbed by the peat.

The scientists point that out the cost of a biosorbent is likely to be much higher than a conventional one, but that it guarantees the rapid decomposition of oil-based contaminants.