Comparison of biostimulation and bioaugmentation for remediation of soil contaminated with spent motor oil

Lipases are serine hydrolases that catalyze the hydrolysis and synthesis of esters formed from glycerol and long-chain fatty acids, by acting at the oil-water interface. Lipases from microbial sources have received heightened attention for an array of industrial applications, and these enzymes have been well exploited in the environmental sector as well. In this article, we present an overview of microbial lipase, including the microorganisms from which it could be produced; the application of recombinant DNA technology tools to produce lipase with enhanced properties, the effective use of waste materials as substrates for lipase production; the usage of statistical tools to efficiently optimize the production medium; lipase purification strategies; and the immobilization of the enzyme on a variety of support materials. The next section of the article provides a gist of its application in diversified spheres and focusses exclusively on the environmentally relevant ones. Lipasecatalyzed esterification, transesterification, and interesterification reactions, an emerging area of green chemistry; lipase-mediated in vitro biopolymer synthesis and degradation; and the application of lipase for remediating fat and oil constituents in wastewater are dealt with in-depth. When its full potential is harnessed, the enzyme could play a pivotal role in environmental management.

Section: Bioremediation Of Oil and Grease (Oandg) Containing Wastewatermentioning

confidence: 99%

An insight into microbial lipases and their environmental facet

Kanmani¹,

Aravind²,

Kumaresan³

2014

“…This is principally associated with inadequate measures in the production, transportation, and refining of crude oil. This issue is more severe in the developing countries where there were no effective regulatory policies on the environment (Escalante Espinosa 2000;Infante 2001;Yazdanparast et al 2004;Osuji and Ezebuiro 2006;Torres et al 2007;Sakari et al 2010;Abdulsalam et al 2011).…”

Section: Introductionmentioning

confidence: 99%

“…In part, this is because the physicochemical technologies have their limitations. They are more expensive to implement at full scale, they are frequently not environmentally friendly, their technologies are complex, and they may lead to destruction of soil texture and fertility characteristics (Abdulsalam et al 2011), compared to bioremediation processes which are gaining ground due to their simplicity, higher efficiency, and cost-effectiveness (Yousefi Kebria et al 2009). One such technology was developed at the turn of the twentyfirst century in the Gulf of Mexico region, which uses simple methods and locally available materials, machinery, and know-how, thereby greatly increasing ease of implementation, and reducing costs (Adams 2004a(Adams , 2008.…”

Section: Introductionmentioning

confidence: 99%

Field-scale evaluation of the chemical–biological stabilization process for the remediation of hydrocarbon-contaminated soil

Adams

Guzmán-Osorio

Domínguez-Rodríguez

2013

Developing countries face the challenge of growing their economy while reducing the negative environmental impacts of industry, thus requiring treatment technologies that are economical and effective. One recent technology developed in the tropical part of Mexico for the remediation of petroleum-contaminated soil was tested in this scale-up project at an industrial level, whereas previously it had only been tested at laboratory scale; 150 m 3 of bentonitic mud, contaminated with weathered hydrocarbons (3.4°API) at *50,000 ppm, was treated with 4 % Ca(OH) 2 , 4 % organic amendment, and a fine-root tropical grass. Hydrocarbons in soil and in leachates, as well as pH, and acute toxicity (Microtox) were monitored for 28.8 months. At the end of the study, basal respiration, root density, and earthworm toxicity were also measured. The hydrocarbon concentration in soil was reduced to 45 %, and toxicity was eliminated. Hydrocarbons in leachates were reduced to *1 mg/l, safe for human consumption. The pH adjustment depended on low soil moisture and was stabilized at 7.1. Intense revegetation resulted in good root density, within 90 % of nearby uncontaminated soil under pasture. Basal respiration was increased to levels comparable to uncontaminated tropical soils with agricultural use, pasture and gallery forest. At an industrial scale, strict moisture control was necessary for good pH stabilization. By controlling these conditions and applying this novel treatment process, it was possible to transform a heavily contaminated geological material into a non-toxic, fertile, soil-like substrate capable of maintaining a complete vegetative cover and microbial activity comparable to similar soils in a tropical environment.

“…To overcome the limitations of these physico-chemical technologies, bioremediation can prove to be an effective and eco-friendly technology which makes use of either indigenous bacteria or introduces exogenous bacterial cultures capable of degrading the contaminant. It has many advantages over physicochemical methods for it being eco-friendly, safe, gives complete mineralization of pollutant which in turn conserves soil texture and characteristics and is also costeffective (Salleh et al 2003;Abdulsalam et al 2011). Many microbial strains are capable of degrading specific hydrocarbon compounds.…”

Section: Introductionmentioning

confidence: 99%

Microbe assisted phytoremediation of oil sludge and role of amendments: a mesocosm study

Nanekar

Dhote

Kashyap

et al. 2013

A mesocosm study was evaluated to elucidate the influence of amendments such as microbial consortium, plant (Vetiveria zizanioides), bulking agent (wheat husk) and nutrients on remediation of oil sludge over a period of 90 days. The experiment was conducted in a 15 m 2 plot which was divided into eight units comprising of soil sludge mixture (1:1) at CSIR-NEERI premises. During the experiment, oil degradation was estimated gravimetrically and polyaromatic hydrocarbons (PAHs) were quantified on GC-MS. Additionally, dehydrogenase activity was also monitored. The treatment integrated with bulking agent, nutrients, consortium and plant resulted in 28-fold increased dehydrogenase activity and complete mineralization of higher PAHs. Furthermore, 72.8 % total petroleum hydrocarbons (TPH) degradation was observed in bulked treatment with plant, nutrients and consortium followed by 69.6 and 65.4 % in bioaugmented treatments with and without nutrients, respectively, as compared to control (33.4 %). A lysimeter study was also conducted simultaneously using Vetiver and consortium to monitor groundwater contamination by heavy metals in oil sludge which showed a marked decrease in the concentrations of metals such as lead and cadmium in leachates. This study validates a holistic approach for remediation of oil sludge contaminated soils/sites which is a burning issue since decades by the use of microbe assisted phytoremediation technology which not only solves the problem of oil contamination but also takes care of heavy metal contamination.