Biofilm treatment of organic waste
Li Ruixue Cai Shenjian Shen Cheng
Abstract: Hazard organic waste has become the consensus, treatment of organic waste pollution is one of the key environmental work. This paper describes the sources of organic waste and hazards, describes the principles of biofilm treatment of organic waste, advantages and disadvantages, discussed its research status and development trends.
Keyword: Biofilm; Organic waste;Treatment 1:Preface
Boiofilm organic gas mainly comes from the petroleum, the chemical industry in the production process emissions.It has the characteristic that the organic matter content of ups and downs, with combustible, have a certain toxicity and there will be some odor.Chlorofluorocarbon emissions will cause the destruction of the ozone layer.Petrochemical production process and storage equipment,printing and other related to petroleum and chemical industry,the use of organic solvents.,Petroleum products for a variety of transportation fuels all above these will cause organic gas.【1】
The main components of organic waste are formaldehyde,acetone,acetic acid,ethyl -ester,additive and other organic gases containing carbon and oxygen and so on . Organic gas damage plant leaf tissue and destroy the ozone layer,For the harm to human body is reflected in many aspects.Benzene is highly toxic solvents,even small amounts can cause long-term damage to the human body,it can accumulate in the
bone marrow and the nervous system,damage hematopoietic tissue and nervous system,cause neurological disorders, reduce the amount of white blood cells in the blood, platelet,worse is suffering from leukemia.PAH and organic compounds have strong carcinogenesis.Benzoic acid can make the protein in a cell deformation or solidification, the systemic poisoning.Nitriles can cause breathing difficulties, can cause suffocation seriously, loss of consciousness until death.Glycol ether solvent in the human body can be formed after the metabolism of toxic,cause permanent damage to the circulatory and nervous system of the body.Female reproductive system would also be affected, serious can lead to infertility.Organic phosphorus compounds can reduce blood cholinesterase activity, resulting in nervous system disorders.About organic sulfur compounds, low concentration of thiol can cause physical discomfort, but death at high concentration.Toluene diisocyanate with low vapor pressure, have a strong stimulating effect on the human cornea, causing eye irritation.Steam into the human body, will damage the function of human liver, kidney, long-term exposure to toluene diisocyanate steam high concentrations of carcinogenic.
There are two main types to treat organic waste gas :one is recovery.The recovery method is physical method,we use the adsorbent and selectively permeable membrane to separate volatile organic compounds in a certain temperature and pressure including active carbon adsorption,condensation method,Pressure swing adsorption method and biofilm..Another is eliminate these organic waste we turn organic matter into carbon dioxide and water using of light, heat, catalyst and microbes, like light decomposition method, the thermal oxidation method, catalytic combustion method,
biological oxidation, corona method, plasma decomposition and so on.【2】 2 :Biofilm treatment of organic waste
2.1 Mechanism of biofilm treatment of organic waste
Mechanism of biofilm treatment of organic waste was first put forward by Ottengraf from Netherlands.The biofilm theory biochemical method of organic waste gas purification process into three steps:
(1)First, the organic pollutants in the exhaust gas on contact with water and dissolved in water.That is, by diffusion into the film by the Film.
(2)Dissolved in the liquid film of the concentration difference between the use of organic pollutants ingredients spread to the biofilm, and was one of the microorganisms to capture and absorb.
(3)Microorganisms into organic contaminants in microbial metabolic processes as their energy and nutrients are broken down by biochemical reactions and eventually converted into harmless carbon dioxide and water.
Later, Sun Pei Shi, who noted that some do not dissolve in water or water-soluble organic matter, difficult to use film diffusion method to explain.So they proposed adsorption - Biofilm Theory.And based on the treatment of low concentrations of toluene gas experiments to establish a dynamic model.【3】Highlights of the theory is: (1)Organic pollutants in the exhaust gas reaches the membrane by diffusion and adsorption to the moist biofilm surface .
(2)Organic matter is captured and absorbed by microbes.
(3)Microbial decomposes contaminants and finally turn into carbon dioxide and
water.
2.2 Advantages of biofilm treatment of organic waste (1)Biodiversity:Both aerobic and anaerobic bacteria
(2)Biofilm low moisture content, a large biomass per unit volume make it has larger processing capacity.
(3)Process is more stable, less consumption, high removal efficiency. 2.3The development of organic waste gas treatment
At present, processing technology of organic waste gas general development into two categories:
decomposition
elimination
and
concentration
and
recovery.
Decomposition is used as the light, electricity, eliminating heat, plasma and microorganisms of the organic compounds into carbon dioxide and water. Concentration and recovery is by adsorption, absorption, condensation and membrane separation, the organic matter concentration recycling.
Decomposition of eliminating treatment without recycling of organic waste gas value, its technology including direct combustion, catalytic combustion method, corona method, plasma method and biological method. Concentration and recovery for treatment of high concentration organic waste and recycling value, its technology absorption method, adsorption, condensation and membrane separation method. Organic waste gas treatment no recycling value, such as odor gas by catalytic combustion method, although the cleaning is thorough, but the cost is relatively high, but also the existence of two pollution; corona, plasma technology has a better application prospect, but there are still some distance from the practical aspects;
biological method of saving energy, low operation cost, rarely formed two pollution, treatment of low concentration organic waste gas (<3g/m-3) effect is better, in Europe and the United States, Japan and other nations have been put into industrial operation.The treatment of organic waste gas by using biological method although late, but the prospect, because of the low concentration organic industrial waste gas treatment and lack of economical and effective measures, biological method can play a role in [4] is very important.
Biological methods mainly include biological filtration, biological washing method and biological trickling filter process of three types, including biological filtration and biological trickling through surface membrane biological filler in microbial treatment of organic waste gas, so these two kinds of methods are known collectively as the biological membrane method [5]. 2.4 The main process form
There are two forms to treat organic gas ：Biofiltration，Biotrickling filtration （1）Biofiltration.
Process:
organic
waste-humidifier-biofilter-purge
gas
emissions.The main device is a humidifier and biofilter. Organic waste gets wet first in a humidifier ,and then into the biofilter，Filler layer in the filter is attached with the biofilm, Liquid substantially stays stationary or slow-speed flow .Moisture, pH, nutrient can be suppled if it is needed.Must ensure gas goes through filter continuously. The filler can be soil, plastic filter, ceramic filter, granular activated carbon, peat, compost, etc. Thickness is about 1m, the area is designed by the gas flow and the effect of treatment .
生物膜法处理有机废气-英语
