Supplying greenhouse with carbon di:oxide free from harmful cpds. - by aerobically growing microorganism using methane, in presence of oxygen, burning prod. and feeding to greenhouse

摘要

In supplying greenhouses with CO2 free from harmful components, micro-organisms which use CH4 are cultured aerobically on natural gas contg. at least 15 vols.% of CH4, in presence of O2 at a ratio of CH4:O2 of 0.35-1.5:1. Gaseous waste prod. is then burned, opt. after addn. of further O2 and/or CH4 and is fed to the greenhouse. Appts. pref. comprises a container holding a bioactive culture of aerobic, CH4-utilising microorganisms in a nutrient soln.. Connected to the container is combustion chamber(s) which are in turn connected to the greenhouse or to means for intermediate storage and/or conditioning. A greenhouse with a surface of 3590 m2 needed a supply of CO2 at a rate of 10 g/square m/h. 72.5 cubic m/h of natural gas, free from S and Hg and contg. 40% CH4, and 197.5 m3/h of air were fed to a reactor contg. the microorganism ZIMET B 502, which was grown in a nutrient salt soln., at pH 5.7 and 38 deg.C for 6 h. Prod. was 12 kg/h of biomass and 21.6 kg/h of CO2. Waste gas contg. 6.06% O2, 3.91% CH4, 5.89% CO2 and 84.14% N2, was burned, giving a further 14.3 kg/h CO2. Ratio of CH4 converted in the bioprocess: CH4 directly burned was 3:1. ADVANTAGE - Gas fed to the greenhouse is free from NOx and contains 0.003% CH4, compared with 0.01% after simple combustion of the natural gas. As less heat is liberated, the CO2 can be fed to the greenhouse even during intense sunlight. Process can use microorganisms, the cell substance of which can be used for fodder or for recovery of cell contents, e.g. water-sol. cpds. affecting plant physiology (e.g. raising yield). In an example, microorganism is pref. the bacterium ZIMET B 502. Natural gas free from Hg and S is used in amt. of 8-50 l/m2 of greenhouse surface. Biological process is carried out so that the residual CH4 concn. in the waste gas is not above 3 vols.%..