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Nov 8, 2017 in Informative
The Role of Chemical Engineering in Environmental Remediation
Green engineering is a phrase used to explain the role of engineering to reduce or eliminate daily carbon emissions. Green engineering is a process through which products and services are designed in order to lower their impact on the environment. This process eliminates the health hazards posed to man and the environment through pollution. The processes used in green engineering should be economically feasible and cost effective when applied to the existing processes of the product design. Environmental remediation is a phrase meaning the restoration of a deeply contaminated location or place to a condition that it will not be a threat to life forms or human health. In conventional clean ups, the contaminated site is usually fenced off to prohibit a human and animal entry but green engineering designs methods that will clean the air, soil and water in such a site. This paper highlights the role of chemical engineering processes and methods in the environmental remediation.
Each year, industries across the world generate multi-billion tons of wastes. This is a potential risk to all the life on the planet and consequently the environmental degradation.
This diagram represents a balanced ecosystem, all carbon emissions should be absorbed by the Biomass.
In addition to that, recycling and managing these wastes is costing enterprises millions of shillings although regulatory measures are in place. From the start of industrialization, laws regarding environmental protection are on the increase, but some have done little to protect the environment against degradation (NRC Board, 2000).
A photo of Agbogbloshie Slum in Accra where millions of computers are dumped annually
Green engineers have resorted to design systems that will remediate the environment from choking wastes. They have used green chemistry methods like selecting chemicals that are not toxic, have low potential hazards, which are eliminated through the reduction of chemical exposures. Environmental designs try to reduce risk to the natural ecosystems, workers in industries and consumers of the goods.
Before designing any process that remediates the environment, green engineers have to access the risks of a production process to the environment and human life. A risk can be expressed as the role of exposures and hazards. A hazard is defined as anything that produces a detrimental effect on the human environment, while exposure is defined as the qualitative assessment of a chemical when it is exposed to the human or animal body, for instance, the skin and the respiratory system. It is vital to note that conventional methods of preventing pollution focus on the reduction of wastes while modern methods of green engineering evaluate the risk posed by the chemicals used in production. Using the approach of risk assessment, engineers have been able to design processes that will be economically beneficial and feasible, while reducing the risk to the environment.
The application of risk concepts has made green engineers to design “green” processes and products. They have optimized designs with the purpose of reducing environmental impacts. Chemicals that need to be eliminated or minimized have been highlighted, and industries are educated on their adverse effects. Green engineers have estimated the risk that the current processes pose to the human environment and people, in addition to accessing the recycle channels and feeding processes.
Processes that Remediate the Environment
Treatment of Wastewater and Industrial Discharge
Chemical Precipitation Industries and sewage systems emit a lot of water contaminated with heavy metals. In the conventional systems, the water is kept in treatment plants where heavy metals are not removed. Heavy metals like lead, mercury, cobalt may not be removed from effluents through the filtering or precipitation processes. Green engineering is evaluating chemical products and synthesizers used in the water treatment. These chemicals may prove to be useful in remediation of wastewater. The methods have to ensure that the precipitates will not deteriorate and discharge heavy metals to the surroundings. The fist method involves the treatment of wastewater using alum and a polymer. These chemicals enable the precipitation of heavy metals in wastewater. In addition to that, they reduce the PH of treated wastewater from about 8.5 and lower it to 7.
Wastewater (left) treated using alum and a polymer results to clear water with a PH of 7 in the next bottle (right).
A Californian Company, ETUS Inc., manufactures Thio-Red, a commercial product that has been successfully used in removing heavy metals from sewage and industrial water. This product reacts with heavy metals to form metal sulfides instead of metal thiocarbonates. The other products include TMT-55 and TMT-15, which are very efficient in precipitating copper, lead, and silver from effluents (Henke 7-55).
Treatment of Wastewater Using Algae
William Oswald, an environmental scientist at Berkeley University, developed the process of treating water using algae photosynthesis in ponds that are openly incorporated. This system is used to treat sewage in almost all countries in the world (Earth Sciences Division, n.d).
Creation of Bioenergy to reduce Carbon Emissions
This system involves the design of systems that will use microbial genomics in relation with biofuels and recovery of hydrocarbons emitted during the production process.
Micriobially Enhanced Hydrocarbon Recovery Method (MEHR)
In the MEHR method, microorganisms, oxygen, nutrients are put in a reservoir with used or contaminated oil in order to enhance oil recovery. The main objectives of these processes are to transform the hydrocarbon components found in oil. This will make oil to be more fluid and viscid. This method can be used to clean environments, which have been contaminated with waste products produced by fossil fuels.
Use of Algae to Generate Biofuel
Algae can be used to generate biofuels for industrial use. Although it is a ubiquitous organism, algae have been used in the pharmaceutical world and it can be applied in the production of clean energy. Algae that absorb carbon are a great potential and an alternative to the use of fossil fuels. One setback with the use of algae to produce biofuel, there is the need of large systems (Earth Sciences Division, n.d).
Ethanol Production from Biomass
Sugar undergoes a series of chemical processes to produce ethanol. This process is referred to as fermentation. Ethanol and carbon dioxide are produced after microorganisms have fermented the sugar.
Treatment of Soil
Intellishare Environmental Company provides a soil remediation oxidizer, vacuum extractor and control systems. These packages can help in restoring the natural components and structure of soil in a contaminated area. In addition to that, the combination of the systems of this soil remediation method can slip through the cracks and help in treating the lower soil layers.
Intellishare Environmental Company soil remediation oxidizer, vacuum extractor and control system.
Processes in Production that can remediate the Environment
Use of chemicals that are less toxic
Green Engineers recommend the use of Poly vinyl formamide that is a less toxic chemical used in the paper industries, water treatment plants, oil recovery, and industries used to design items for personal care. This chemical is not a neurotoxin even when ingested. Polyacrylamide, a chemical used in the same process, is very toxic and can cause paralysis of the Central Nervous System when ingested. The wastes produced are very expensive to clean up. In addition to that, CNS paralysis can lead to loss of lives, livelihoods, and increased dependency (Van Noordern, 2011).
Green System Design
Piping used in industries should slope downwards to reduce the amount of solvents used. Short and big pipes reduce the flow dram while using very low energy. Industries should not have dead-end sample points in order to reduce wastes. Other green engineering changes that can be made to the industry include the use of efficient raw materials that are somehow refined. For instance, water used in the refinery industries can be treated before being used to reduce sludge wastes. Selectivity in rectors should also be increased to reduce the time taken to mix and catalyze. This can be enhanced by using highly efficient reactors, which take little residence time. Industries should use efficient separation processes. Conventionally, separate reaction and separation processes demand the use of large amounts of solvents while consuming a lot of energy or pressure. Green technology has developed novel methods that allow products to separate by themselves due to their physical and chemical properties. The other method is through combined reaction and separation processes that occupy little space, consume less energy, and are more efficient because it allows almost 99% conversion. Distillation and liquid-liquid extraction (LLE) processes can also be combined to increase efficiency and reduce wastes. PET bottles can be recycled using simple processes. The colors of the bottles are sorted using spectroscopy since PET bottles have a characteristic green dye incorporated into their surface. The bottles are shredded and washed to remove labels. In the same water, HDPE and PET bottles are separated through their different densities. The aluminum ring is removed using an electrostatic ring, and the bottles can be reused.
Efficiency Maximization Systems
Processes, products should be designed to maximally utilize energy, mass, time and space in an efficient manner. Heat integration systems should be coupled to increase efficiency while reducing wastes. For instance, in a cooling plant and heating plant, the systems can be interconnected in a way that steam from hot water is released to heat cold water. This reduces the loss of energy to the surroundings.
According to La Chatelier’s principle, if stress is applied to a system, the system reacts by offsetting itself to relive the applied pressure. In industrial terms, stress can be defined as any factor that upsets the concentration gradient, for instance, temperature and pressure. Increase of an input into a production system will lead to an increase in the generation of an output. This design aims to minimize the quantities of resources used, while getting a good amount of output. In this context, manufacturing systems can be based on timely manufacturing. Timely manufacturing refers to the production of goods to meet the consumers’ quantity, quality and in their time of demand. This method implies that the resources, equipment, and labor are available when there is a demand created by the consumers. This is a form of a planned manufacturing system that manages the wastes, overproduction, reduces waiting time, inputs and outputs. This enables that industries have minimized excess while meeting the needs of their consumers. Chlorination of water is simple and makes millions of water safe within a short time. This method spends little energy of water treatment plants that use unnecessary resources like heat, power and labor. Green engineering advocates for methods like express metal deposition over metal casting because the wastes, produced by the earlier method is little.
Reduction of Complexity
The use of natural systems should not be avoided in the manufacturing process. The higher the complexity is involved in making a product, the lower there are the chances of recycling the material. Products should be made in a way that they are durable rather than those ones that have a very long period of use. If production processes target immortality, there is a high risk of the products to the environment and many potential hazards to the human life. For instance, the eco-fill food grade input is constituted from water and starch. It can be used in the industrial production, very durable, and exerts little burden to the environment because it is mortal. The other method that eliminates environmental hazards is the use of polylactic acid to manufacture fibers and plastics over polyacrylic acid, which is non-biodegradable (Center for Green Energy and Green Engineering, 2011).
In conclusion, green engineering has taken a step in redesigning the production processes to eliminate the wastes and environmental pollution. This form of engineering aims at renewable products and services that pose a minimal or no risk to the environment and other life forms. Products which consist of components that can be reused to reduce wastes in the environment. All companies should embrace these methods to reduce the hazards and risks posed to the environment because prevention of dumping is less expensive than cleaning up.