Lexikon
an amendment-enhanced bioremediation technology for the treatment of POPs involves the creation of sequential anoxic and oxic conditions. The treatment process involves the following:
1. Addition of solid phase DARAMEND® organic soil amendment of specific particle size distribution and nutrient profile, zero valent iron, and water to produce anoxic conditions.
2. Periodic tilling of the soil to promote oxic conditions.
3. Repetition of the anoxic-oxic cycle until the desired cleanup goals are achieved.
The addition of DARAMEND® organic amendment, zero valent iron, and water stimulates the biological depletion of oxygen, generating strong reducing anoxic conditions within the soil matrix. The diffusion of replacement oxygen into the soil matrix is prevented by near saturation of the soil pores with water. The depletion of oxygen creates a low redox potential, which promotes dechlorination of organochlorine compounds. A cover may be used to control the moisture content, increase the temperature of the soil matrix and eliminate runon/run off.
The soil matrix consisting of contaminated soil and the amendments is left undisturbed for the duration of the anoxic phase of treatment cycle typically 1-2 weeks. In the oxic phase of each cycle, periodic tilling of the soil increases diffusion of oxygen to microsites and distribution of irrigation water in the soil. The dechlorination products formed during the anoxic degradation process are subsequently removed trough aerobic oxic biodegradation processes, initiated by the passive air drying and tilling of the soil to promote aerobic conditions.
Addition of DARAMEND® and the anoxic-oxic cycle continues until the desired cleanup goals are achieved. The frequency of irrigation is determined by weekly monitoring of soil moisture conditions. Soil moisture is maintained within a specific range below its water holding capacity. Maintenance of soil moisture content within a specified range facilitates rapid growth of an active microbial population and prevents the generation of leachate. The amount of DARAMEND® added in the second and subsequent treatment cycles is generally less than the amount added during the first cycle.
The additive enhanced bioremediation was successfully applied for toxaphene and DDT contaminated soil and sediment.
converting a bare or agricultural space by planting trees and plants; reforestation involves replanting trees on areas that have been cut or destroyed by fire.
inhaling fluid or a foreign body into the bronchi and lungs, often after vomiting.
See also: aspiration
biorefinery is a complex plant that integrates biomass conversion processes and technologies to produce fuels, power, heat, and value-added chemicals from biomass. The term biorefinery is analogous to petroleum refinery, which produce multiple fuels and products from petroleum.
Biorefining is the processing of biomass into a wide range of bio-based products, such as food, feed, chemicals, materials and bioenergy, including biofuels, power and/or heat.
Fully equipped biorefineries − similar to ptroleum refineries − do not exist yet, but combined heat and power (CHP) technologies generating electricity and process heat for smaller communities are more and more widespread in Europe (1).
The biomass to be converted into heat, energy, fuel or materials can be of plant or microbial as well as organic waste origin. There are many individual ‘enabling technologies’ behind a biorefinery process. These include mechanical pretreatment, heat treatment, chemical/enzymatic cell wall degradation, fermentation, isolation/purification, conversion etc.
The total chain of processing events is always tailor-made and optimized for a given biomass source and the applications aimed at. For unicellular organisms like algae, the first steps in the total biorefinery process differ strongly from that for plant-based material. Instead of mechanical harvesting and pretreatment of the crude plant material, efficient isolation of dispersed cells from the production medium is required. No lignin or hemicellulose is present, but many algae have cell walls that need to be broken down to allow efficient isolation of compounds of interest. In the later stages where individual compounds are isolated and converted, processes are more similar.
In case of an algal biomass biorefinery technology consists of the the following steps (2):
- Isolation is necessary unless direct milking of a desired algal product is possible. The first step in microalgae value creation is the isolation (harvesting) thereof from the production medium. There are several techniques available for this.
- Purification strategies for individual components from algal biomass are highly diverse, as a direct consequence of the complexity and diversity of the algae biomass ‘matrices’ and the physico-chemical properties of the compounds of interest therein.
- Conversion: many isolated algal components will need to be (bio) chemically converted to match the exact application needs, e.g. conversion by transesterification.
The tactical biorefinery (3) first separates organic food material from residual trash, such as paper, plastic, Styrofoam and cardboard. The food waste goes to a bioreactor where industrial yeast ferments it into ethanol, a "green" fuel. Residual materials go to a gasifier where they are heated under low-oxygen conditions and eventually become low-grade propane gas and methane. The gas and ethanol are then combusted in a modified diesel engine that powers a generator to produce electricity.
Sources:
(1) http://en.wikipedia.org/wiki/Biorefinery
(2) http://www.algae.wur.nl/UK/technologies/biorefinery/
(3) http://news.uns.purdue.edu/x/2007a/070201LadischBio.html
bioremediation uses microorganisms to degrade organic contaminants in soil, sludge, and solids either excavated or in situ. The microorganisms break down contaminants by using them as a food source or cometabolizing them with a food source. Aerobic processes require an oxygen source, and the end products typically are carbon dioxide and water.
Anaerobic processes are conducted in the absence of oxygen, and the end products can include methane, hydrogen gas, sulfide, elemental sulfur, and dinitrogen gas.
Ex situ bioremediation includes slurry-phase bioremediation, in which the soils are mixed in water to form a slurry to keep solids suspended and microorganisms in contact with the soil contaminants, and solid-phase bioremediation, in which the soils are placed in a cell or building and tilled with added water and nutrients.
Land farming, biopiles, and composting are examples of ex situ, solid-phase bioremediation. In situ bioremediation is bioremediation in place, rather than ex situ. In situ techniques stimulate and create a favorable environment for microorganisms to grow and use contaminants as a food and energy source. Generally, this means providing some combination of oxygen, nutrients, and moisture, and controlling the temperature and pH. Sometimes, microorganisms that have been adapted for degradation of specific contaminants are applied to enhance the process.
Source: US-EPA, Clu-In: http://www.clu-in.org/techfocus/default.focus/sec/Bioremediation_of_Chlorinated_Solvents/cat/Overview/
region of a chromosome with which spindle fibers are associated during cell division, allowing orderly movement of daughter chromosomes to the poles of the daughter cells.
ecoremediation is based on the co-operation of plants, soil and soil living microorganisms, mainlyof the rhyzosphere. Ecoremediation comprises systems, processes and technologies which function in natural ecosystems, or as an artificial part of a natural ecosystem. In ecoremedial technologies the man-made artificial ecosystem is able to compensate adverse environmental effects of chemical substances or contaminated environmnetal compartments or phases. Its function is based on the close co-operation of soil microbes and plants, and its proper function depends on the balanced and controlled element- and water-cycle of the artificial ecosystem designed for remedial purposes.
Ecoremedial technologies can be applied for waste water treatment, for the remediation and maintenance of lakes, reservoirs and wetlands, for complex rehabilitation and reclamation of landfills and for the complex rehabilitation or remediation of contaminated or deteriorated soil.
Ecoremediation is used for long term and sustainable protection, restoration and complex rehabilitation of environment of damage or exposed to potential damage. Ecoremedial technologies are cost- and eco-efficient in protection of water resources, streams, rivers, lakes, groundwater and the sea and in ensuring the sustainable quality of the environment on long term.The most important characteristics of ecoremedial technologies are their adaptive character, their high buffer and self-protective capacities against adverse affects of antropogenic origin, and they are highly potent in preservation of natural habitats and biological diversity.
Eco-remediation has more areas, such as bioremediation, utilising soil microflora; phytoengineering utilising plants for many purposes, artifically built lakes, aerobic and anaerobic wetlands, reactive soil zones, etc., are all considered as ecoremedial technologies.
fracturing is a way to crack rock or very dense soil, like clay, below ground. It is not necessarily a cleanup method in itself. Rather, fracturing is used to break up the ground to help other cleanup methods work better. The cracks, which are called fractures, create paths through which harmful chemicals can be removed or destroyed.
Hydraulic fracturing uses a liquid?usually water. The water is pumped under pressure into holes drilled in the ground. The force of the water causes the soil (or sometimes rock) to crack. It also causes existing fractures to grow larger. To fracture soil at greater depths, sand is pumped underground with the water. The sand helps prop the fractures open and keep them from closing under the weight of the soil.
Pneumatic fracturing uses air, to fracture soil. It also can help remove chemicals that evaporate or change to gases quickly when exposed to air. When air is forced into the soil, the chemicals evaporate and the gases are captured and treated above ground.
Air can be forced into the ground at different depths within a hole. When air is forced near the ground surface, the surface around the holes may rise as much as an inch, but will settle back close to its original level. In both pneumatic and hydraulic fracturing, equipment placed underground directs the pressure to the particular zone of soil that needs to be fractured.
Blast-enhanced fracturing uses explosives, such as dynamite, to fracture rock. The explosives are placed in holes and detonated. The main purpose is to create more pathways for polluted groundwater to reach wells drilled for pump and treat cleanup.
Source: US-EPA, Clu-In: http://www.clu-in.org/techfocus/default.focus/sec/Fracturing/cat/Overview/
Monitored Natural Attenuation (MNA) is the monitoring of the effects of naturally occurring physical, chemical, and biological processes or any combination of these processes to reduce the load, concentration, flux or toxicity of polluting substances in soil and groundwater in order to obtain a sustainable remediation objective.
soil bioremediation based on aerobic oxidation means that the soil remediation is based on aerobic biodegradation. The microbiological biodegradation occurs in this case on a high redoxpotential of +0,8-+0,6 Volt. The degrading microorganisms utilise the pollutant as enbergy sources. The source of oxigen is the atmospheric air, soil air, or dissolved oxigen in soil moisture or ground water. If the oxigen-concentration is low, the technologist can increase it by aeration of the soil or the groundwater as well as by adding peroxide substances or other oxigene release compounds ORC to serve as oxigene source for the activation of the aerobic soil microbes.
a bioreactor landfill operates to rapidly transform and degrade organic waste. The increase in waste degradation and stabilization is accomplished through the addition of liquid and air to enhance microbial processes. This bioreactor concept differs from the traditional "dry tomb" municipal landfill approach.
A bioreactor landfill is not just a single design and will correspond to the operational process invoked. There are three different general types of bioreactor landfill configurations:
- Aerobic - Leachate is removed from the bottom layer, piped to liquids storage tanks, and recirculated into the landfill in a controlled manner. Air is injected into the waste mass, using vertical or horizontal wells, to promote aerobic activity and accelerate waste stabilization.
- Anaerobic - Moisture is added to the waste mass in the form of recirculated leachate and other sources to obtain optimal moisture levels. Biodegradation occurs in the absence of oxygen (anaerobically) and produces landfill gas. Landfill gas, primarily methane, can be captured to minimize greenhouse gas emissions and for energy projects.
- Hybrid (Aerobic-Anaerobic) - The hybrid bioreactor landfill accelerates waste degradation by employing a sequential aerobic-anaerobic treatment to rapidly degrade organics in the upper sections of the landfill and collect gas from lower sections. Operation as a hybrid results in an earlier onset of methanogenesis compared to aerobic landfills.
The Solid Waste Association of North America (SWANA) has defined a bioreactor landfill as "any permitted Subtitle D landfill or landfill cell where liquid or air is injected in a controlled fashion into the waste mass in order to accelerate or enhance biostabilization of the waste." The U.S. EPA is currently collecting information on the advantages and disadvantages of bioreactor landfills through case studies of existing landfills and additional data so that EPA can identify specific bioreactor standards or recommend operating parameters.
Source: US-EPA, Clu-In − http://www.clu-in.org/techfocus/default.focus/sec/Bioreactor_Landfills/cat/Overview/