Microbial Clean-up of POPs in a Subsurface Environment

Microbial Clean-up of POPs in a Subsurface Environment Persistent Organic Pollutants (POPs) consist of a wide range of contaminants with each group presenting different challenges and having different processes for bioremediation. Although Polycyclic Aromatic Hydrocarbons (PAHs) are not a POP under the Stockholm Convention, they are widespread in the environment and can be toxic, mutagenic and carcinogenic. Specific PAHs are seldom found in isolation and interactions can increase the aforementioned properties (15). This paper describes a new product for the clean-up of PAHs in a subsurface environment. A new product for the clean-up of PAHs will be described including factors that could enhance or limit its potential, based on technical and literature reviews. The engineering and legal aspects of applying the product will also be examined. 3.1 Metabolic Characteristic of PAH Degradation Product       The majority of research into PAH degradation has focused on aerobic rather than anaerobic processes so this product has been designed using findings from aerobic studies (15). Constituents of this product are shown in Figure 1. Indigenous bacteria may have evolved more efficient pathways and enzymes to degrade PAHs compared to commonly cultivated microorganisms (15). If these are present only the biostimulation part of the product may be required to feed the bacteria or change groundwater chemistry to create favourable growth conditions. If the existing biomass is not viable or doesnt contain specific genes or species capable of degrading PAHs, the bacteria consortia part of the product can be introduced as well. In addition, more bacterial species are capable of degrading low molecular weight (LMW) PAHs compared to high molecular weight (HMW) PAHs and if testing shows the indigenous bacteria only possess strains able to degrade LWM PAHs the bacteria consortia part of the product should be used. A consortia can be more effective than one particular strain due to metabolic diversity and co-operative metabolic activates for example where products produced by one strain are further degraded by other strains possessing suitable catabolic pathways (8) A consortia cannot be formed by simply mixing any bacterial strains know to degrade PAHs as they may not be compatible or form co-operative metabolic activities (17). Also pre-exposure of bacteria to hydrocarbons has be shown to increase the degradation rate (11). Therefore the most effective remediation may be achieved by developing a consortia from inoculants isolated from an environment impacted by long term contamination. The consortium in this product consists of 4 strains: Pseudomonas (MTS-1, KC3), Cupriavidus (MTS-7) and Bacillus (KC5) and was formed by enriching and isolating bacteria from a manufactured gas plant site (17). The strains were then identified through molecular cloning and gene sequencing, mixed and the most effective PAH degrading consortia selected. The consortia has been shown to degrade PAHs in soil slurry by 80-90% for LMW PAHs and 60-70% for HMW PAHs compared to natural attenuation rates of 55% and 40% for LMW and HMW PAHs respectively. Figure 2 shows the upper pathway for the aerobic degradation of PAHs. HMW PAHs are degraded first followed by LMW PAHs and carbon dioxide and water formed as by-products (5). Dioxygenases are intracellular so PAHs must be taken in by cells for degradation to take place. Degradation rates depend on the mass transfer rates of contaminants from the solid or bound phase to the aqueous phase where they are bioavailable (8).   This can be increased by increasing the surface area between the substrate and the aqueous phase through the addition of surfactants (8). Concentrations of PAHs in the aqueous phase are proportional to the amount of surfactant available (8,11). For increased efficiency the biostimulation part of this product contains surfactants that have been shown to solubilize benzo[a]pyrene from the soil by 1000 times more than its water solubility plus all strains in the consortia are biosurfactant producers (13) (17). 3.2 Genetic Modification Degradation rates could be increased by molecular cloning of genes responsible for PAH degradation, into highly replicating plasmids in bacteria (8). Genetic engineering could also be used to introduce or modify membrane proteins to facilitate transportation of hydrophobic POPs into the cellular interiors of microbes or cells could be modified to enable catabolic reactions on their surface (2). Alternatively, protein engineering could enhanced degradative capabilities by modifying catabolic enzymes so one strain can catabolize several POPs or so catabolic enzymes can degrade dead end products (2). Genetic engineering is expensive, can be controversial, there may be difficulties in getting genetically engineered microbes to survive in the environment and gene transfer among microbes in the environment may lead to the emergence of new species (2) (4). It was therefore decided not to use genetic engineering due to cost and it would unlikely be acceptable to a regulator. (alex) 4.1 Factors That Could Enhance or Limit Potential of Product 4.1.1 Properties of Pollutant The longer an organic substance remains in contact with soil the more the bioavailability decreases due to the formation of bound residues. Bioavailability is the ability to be transported across a cell membrane for intercellular metabolism as with this product or the availability for extracellular metabolism. PAHs can also get trapped in coal tar or black carbon particles reducing their bioavailability () The bioavailability of POPs is low due to their high octanol/water partition coefficient (Kow) meaning they are relatively hydrophobic whereas microbes and their catalytic enzymes are optimised for hydrophilic surroundings.   LMW 2-3 ring PAHs such as anthracene with lower Kow values, high water solubility and volatility are more mobile and therefore more rapidly degradable compared to HMW 4-7 ring PAHs such as Benzol[g,h,i]perylene which may be mutagenic and carcinogenic (4)(8). 4.1.2 Properties of Contaminated Environment The concentrations of soil organic matter and inorganic material effects the bioavailability of pollutants and reduces the survival of exogenous microorganisms (3). Where there is high organic and clay content PAHs are protected by sorption to organic matter and diffusion into micropores, thus limiting their degradation (4). Temperature will impact the product as the rate of organic pollutant desorption from soil to aqueous phase increases as temp increases. For PAHs the soil water partition-coefficient decreases by 20-30% for every 10oc rise in temperature between 5 and 45oc (11). In addition with increased temperature dissolved oxygen decreases and the ability of the bacteria to cope with temperature ranges may affect the product performance (4)(15). Lack of soil nutrients, bioavailability of carbon sources, presence of additional pollutants have been shown to inhibit biodegradation by affecting the physiology and ecology of microorganisms (17) (4). However, as shown in Table 1, this product contains nutrients and a carbon source for biostimulation. Heavy metal contamination is often found with PAHs but this product is designed with metal tolerant bacterial strains (17). The bacteria in this product are most efficient at degrading PAHs near pH7 so pH adjusters are also included. Other properties of the contaminated environment that could affect the products potential include adverse effects in soil microcosm due to competition between indigenous and exogenous microorganisms and interactions of the inoculated bacteria with protozoa and bacteriophages (3). Low soil water content will result in decreased substrate availability and may have physiological effects on microorganisms due to cell dehydration (3). 4.2 Engineering Challenges for Field Application of Product Figure 2 shows the stages in the field application of the product which needs to be tailored to site specific conditions. The product will be sold in the form a soluble injection compound that will be injected upstream of groundwater flow through injection wells, extracted downstream and recirculated. Table 2 shows some of the engineering challenges in the application of the product. 4.3 Legal Framework for Field Application of Product Local Authorities are responsible for determining if land or waters are contaminated and are the lead regulator except for Special Sites where SEPA is responsible. As shown in table XXX contamination can be addressed through the contaminated land regime under Part 2A of the Environmental Protection Act 1990 or though planning controls. Whenever possible remediation should be carried out by agreements with the enforcing authority rather than by means of a Remediation Notice. If a notice is served it will specify the action required and timescales. A mobile plant licence may be required for the treatment of contaminated land and may be regarded as an authorisation for the treatment of groundwater under The Water Environment (Controlled Activities) (Scotland) Regulations 2011 (9). When SEPA issue such a license a site specific working plan must be agreed with them. Soil Guideline Values (SGVs) represent trigger levels for concentrations of pollutants in soils that may pose a risk to human health. They dont represent the threshold at which harm occurs or unacceptable levels in terms of Part 2A of the Environmental Protection Act 1990 but they may be a starting point for the risk assessment process for determining if the land is contaminated or remediation has been successful (6).   There are no statutory standards for soil contamination as site specific risk assessment taking into account the sources, pathways and receptors affecting a particular site (7). The first part of the product is the biostimulation part containing elements to promote bacterial growth, a source of carbon, pH adjusters, an oxygen release compound and surfactants to increase the bioavailability of PAHs. If the indigenous bacteria are not capable of degrading PAHs present the bioaugmentation part should also be used. The bacterial strains in the consortia are biosurfactant producers and are capable of degrading HMW PAHs. The legal framework requires a site specific approach to the use of the product. Also the field application needs to be tailored to site specific conditions with environmental monitoring before, during and after application.   

Travel Life

My travel experience During the first time I stepped on the plain I was so exited about it, but when the plane started to fly I cried because I was still 3 years old I was with my dad and my mom I had so much fun traveling then I told my dad can we travel every year he said okay then I became happier and my father kept his promise every year we go traveling in some parts of Asia like Taiwan, hong kong, Singapore, Cambodia, china, Malaysia , Thailand, Indonesia, Vietnam, and others it was so much fun because you get to see places that you never imagined and I felt so good about it.Two years ago we went to Taiwan, with my father and my cousin during the plane ride our ears was hurting so much I really don’t know why so I went to the washroom and checked maybe my ears where dirty but no I asked my daddy he said it was about some engines in the plane that makes you ears hurt.We arrived at Taiwan early in the morning I was so sleepy then we had to hind our hotel(which was so comfor table and such a good place)then after another day we started exploring some beautiful places in like the garden, and Taipei 101 it was so high and it had the most beautiful view in whole Taipei. We only spent 1 week because it was sembreak only in October so I had missed Taiwan ever since. Then last year we went to India my country (that I still really miss so much) for ma little vacation during summer it really felt good to smell the breeze in the place where you (kainda) grow up.Then i felt so good seeing my grand parent's again in such a long time and also some of my relative like my aunt and uncle but the days did no last long the day we are going back to the Philippines I cried so much because I didn’t want to go back I wanted to live there but I cant my family is here so I have to stick with them as well so every day I kept on calling to know how are they and kept on asking me how is my travel life.My traveling life mearns everything to me because I cannot just stay in one play my whole life because you got a whole life to spent and I what to see the world with it because of what every one say life it to short but not for me because you have to embrace your life to be happy to experience every thing that you did no know about the world the cause that is your life you have to live it in the fullest and no just by traveling one single country but all of it for you to see the world before it stopes in a moment.My traveling experience is no just by going to that place but to fell it you have got to see it fell it and do it ti like then for you to have fun at the fullest that never stopes for to have a memories of what you have being doing your whole life and foe you to have al long and good experiencing life with people you what to be with and people you never you that will become you friends so never think traveling is no just going to different countries but to embrace that country like is is yours.

Entering The Halls Of Education - 1293 Words

I decided to enter the halls of education because I work well with a controlling and leadership title and, being controlling, I decided to use that into good energy. Another reason I have decided to go into the field of education as well is to make myself more marketable after graduation. Other than that, I wanted to be in the setting of adolescents because I have had my experience with early childhood education and did not want to stop at that level of teaching. My experience of four years in an early childhood environment has taught me a lot about patience. However, when it comes to that age group I have realize that that age group is very threatening. For instance, if a child plays very roughly when his/her classmates and gets a minor scratch or burse, I have witnessed parents accuse the teacher of abusing their child, when nothing of that nature has happened. 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Importance of the US Presidential Primaries

The U.S. presidential primaries and caucuses are held in the various states, the District of Columbia, and territories of the United States as a key part of the process of nominating candidates for election to the office of President of the United States. The U.S. presidential primary elections typically start in February and do not end until June. How many times do we have to vote for a new President of the United States, anyway? Why cant we just go to the polls once in November and be done with it? Whats so important about the primaries? Presidential Primary History The U.S. Constitution doesn’t even mention political parties. Nor does it provide a method for choosing presidential candidates. It was not that the Founding Fathers did not anticipate political parties as they had known them in England would come along; they simply were not keen to seemingly sanction party politics and its many inherent ills by recognizing it in the nation’s Constitution. In fact, for the first confirmed official presidential primary was not held until 1920  in New Hampshire. Until then, presidential candidates were nominated solely by elite and influential party officials without any input from the American people. By the late 1800s, however, social activists of the Progressive Era began to object to the lack of transparency and public involvement in the political process. Thus, today’s system of state primary elections evolved as a way to give the people more power in the presidential nomination process. Today, some states hold only primaries, some hold only caucuses and others hold a combination of both. In some states, the primaries and caucuses are held separately be each party, while other states hold â€Å"open† primaries or caucuses in which members of all parties are allowed to participate. The primaries and caucuses start in late-January or early-February and are staggered state-by-state to end by mid-June before the general election in November. The state primaries or caucuses are not direct elections. Rather than choosing a specific person to run for president, they determine the number of delegates each partys national convention will receive from their respective state. These delegates then actually select their party’s the presidential nominee at the party’s national nominating convention. Especially after the 2016 presidential election, when Democratic Party candidate Hillary Clinton won the nomination over popular challenger Sen. Bernie Sanders, many rank-and-file Democrats argued that the party’s often-controversial â€Å"superdelegate† system circumvented, at least to an extent, the intent of the primary election process. Whether the Democratic Party leaders will decide to retain the superdelegate system or not remains to be seen. Now, on to why the presidential primaries are important. Get to Know the Candidates First, primary election campaigns are the main way voters get to know about all the candidates. After the national conventions, voters hear mainly about the platforms of exactly two candidates -- one Republican and one Democrat. During the primaries, however, voters get to hear from several Republican and Democratic candidates, plus the candidates of third parties. As media coverage focuses on the voters of each state during primary season, all the candidates are more likely to get some coverage. The primaries provide a nationwide stage for the free and open exchange of all ideas and opinions -- the foundation of the American form of participatory democracy. Platform Building Secondly, the primaries play a key role in shaping the final platforms of the major candidates in the November election. Lets say a weaker candidate drops out of the race during the final weeks of the primaries. If that candidate succeeded in winning a substantial number of votes during the primaries, there is a very good chance that some aspects of his or her platform will be adopted by the partys chosen presidential candidate. Public Participation Finally, and perhaps most importantly, the primary elections provide yet another avenue through which Americans can to take part in the process of choosing our own leaders.  The interest generated by the presidential primaries moves many first-time voters to register and go to the polls. Indeed, in the 2016 presidential election cycle, more than 57.6 million people, or 28.5% of all estimated eligible voters, voted in the Republican and Democratic presidential primaries – just slightly less than the all-time record of 19.5% set in 2008 – according to a report by the Pew Research Center. While some states have dropped their presidential primary elections due to cost or other factors, the primaries continue to be a vital and important part of Americas democratic process. Why the First Primary is Held in New Hampshire The first primary is held in New Hampshire during early February of election years. Taking pride in the notoriety and economic benefit of being the home of â€Å"First-In-The-Nation† presidential primary, New Hampshire has gone to great lengths to ensure it maintains its claim to the title. A state law enacted in 1920 requires that New Hampshire hold its primary â€Å"on the Tuesday at least seven days immediately preceding the date on which any other state shall hold a similar election.† While the Iowa caucuses are held before the New Hampshire primary, they are not considered a â€Å"similar election† and rarely draw the same level of media attention.