Shallow and nicely heated water reservoirs are notable for high biomass production and increased amount of organic matter. Such water reservoirs often “bloom” during a period of explosive propagation of algae, and their bottom is covered with a thick layer of organic sediments. Russian scientists suggest using this organic matter for making biological fuel, an alternative for hydrocarbon fuel.

Researchers from Siberian Federal University and the Institute of Biophysics (Siberian branch of Russian academy of sciences) believe that organic-rich bottom sediments of such water reservoirs can be effectively transformed into raw materials for biodiesel production.

Common technique for biodiesel production is a chemical reaction of animal or plant fatty materials with methanol in presence of a catalytic agent. The reaction results in ethers, which are considered to be high-quality fuel, almost as good as common diesel fuel. Biodiesel is not toxic for the environment, is easily degraded under natural conditions, and has other positive sides. Except for biodiesel is twice as expensive as common diesel. About 60-75 per cent of the costs come from growing and harvesting plant material for biodiesel production.

Researchers from Siberia suggest replacing “biodiesel” plants, like rape, with organic silt and mud, which are taken out of water reservoir, when they are cleaned. Bottom sediments, especially those from “blooming” water reservoirs, contain large amount of microalgae. These microscopic plants are rich in fatty material and can become a basic component of biodiesel production.

In order to find evidence for the abovementioned hypothesis, researchers conducted experiments with bottom sediments of a small Siberian eutrophic lake Bugach. This lake covers only 0.32 square kilometers and has mean depth of 2 meters and maximum depth of 7 meters.

During the experiments researchers collected sediment samples from various depths, extracted fatty acids from silt, purified them and added methanol for ether production. Composition of fatty acids had a strong impact on chemical properties of methyl ethers: burning temperature, oxidation resistance, amount of calories released during full burning of one gram of ether. Preliminary studies showed that biodiesel from bottom sediments met all European standards for such kind of fuel.

The tricky thing is that bottom sediments contain only 0.24% of fatty acids in their dry weight – much less than is usually found in plant or animal materials, however, researchers still think that biodiesel production from bottom sediments can be economically rational, since sediments cost nothing, they only need to be collected from the bottom and prepared for chemical processing.

Every year ponds and lakes are cleaned, producing heaps of bottom sediments – enough for small plants of biodiesel production. Researchers believe that their innovation can help solve two problems at the same time – processing of bottom sediments and ecologically friendly biofuel production.

Source: Science & Technologies

Anna Kizilova