Bioremediation a potential approach for soil contaminated with polycyclic aromatic hydrocarbons: An Overview

Polycyclic aromatic hydrocarbons (PAHs) represent a group of priority pollutants which are present at high concentration in soils of many industrially contaminated sites. Standards and criteria for the remediation of soils contaminated with PAHs vary widely between countries. Bioremediation has gained preference as a technology for remediation contaminated sites as it is less expensive and more environmental friendly. Bioremediation utilizes microorganisms to degrade PAHs to less toxic compounds. This technology degrades contaminants through natural biodegradation mechanisms or enhanced biodegradation mechanism and can be performed in-situ or ex-situ under aerobic or anaerobic conditions. The purpose of this paper is to highlight potential of using isolated strains from municipal sludge on soil remediation. Several indigenous bacteria from municipal sludge namely genus Micrococus, Sphingomonas, and Corynebacterium demonstrated a high removal rate of PAHs with more than 80% of lower molecular weight of PAHs degraded after one week incubation. Laboratory studies had established that these genus able to degrade PAHs on contaminated soil. The successful application of bacteria to the bioremediation of PAHs contaminated sites requires a deeper understanding of how microbial PAH degradation proceeds. An overview of research focusing on biodegradation of PAHs will be presented

Degradation of Phenanthrene in Liquid Culture and Sand Slurry by Corynebacterium urealyticum

Most studies on PAHs biodegradation evaluated the degradation potential of microorganisms under indigenous condition in either liquid or solid. There are limited studies on evaluation of the same microorganisms in degrading PAHs under non-indigenous condition in both liquid and solid media. This study investigated the potential of the bacterium, Corynebacterium urealyticum isolated from municipal sludge in degrading phenanthrene in both liquid and solid media. Batch experiments were conducted over 20 days. Batch reactors containing artificially contaminated phenanthrene minimal media and sand slurry were inoculated with bacterium culture. Percentage phenanthrene degradation in liquid culture and sand slurry were found to be 87% and 29%, respectively. Apart of having higher rate in liquid culture, the degradation activity by bacterium remain active throughout the experiment.  There were no significant differences on the degradation of phenanthrene at low and high initial phenanthrene concentrations in liquid cultures, which differed to the observation in sand slurry. From the viable count analysis, it was observed that this bacterium immediately adapted to the new environment. This study shows that Corynebacterium urealyticum show better capability in degrading phenanthrene in liquid culture compared to sand slurry. Keywords: Bioremediation, Corynebacterium urealyticum, liquid cultures, Phenanthrene, sand slurry

Identification of bacterial strains capable of degrading Malaysian petroleum sludge / Noor Fazreen Dzulkapli ... [et al.]

In an organic sludge bio degradation process, identification of bacterial strains with effective biodegradation capabilities indigenous to the sludge is an important step as isolation and subsequent usage of such strains can enhance the rate of the biodegradation process. In this study, the identification of bacterial strains capable of degrading Malaysian petroleum sludge was carried out using a biolog system kit subsequent to enrichment, isolation and degradation processes. A total of 53 purified strains was obtained from the isolation process. Three strains, namely, Clavibacter michiganesis ss insidiosus, Rhodococcus rhodochrus and Brevibacterium otitidis showed favorable degradation results for nearly all hydrocarbons especially for polycyclic aromatic hydrocarbon (PAHs) (anthracene, phenathrane and dibenzothiophene). Brevibacterium otitidis is especially interesting since it is the first time such a strain has been reported to have good PAHs degradation capabilities

Exfiltration from sewers: effects of different types of leakage / Mohd Ashaari Ab Wahab ... [et al.]

This research was conducted to study exfiltration of wastewater from gravity sewers. Exfiltration through different types of sewer leaks were studied. With the different size of leakage areas and a constant thickness of soil bedding, it was found that the exfiltration rate reduces and became constant over a duration of one (1) to three (3) days. Knowing the exfiltration rate, the time taken for the polluted water exfiltrate from sewer pipes to reach the groundwater can be determined so that preventive measures can be taken to prevent it. From studies conducted, it can be shown that the size of the leakage area was found to play an important role in determining the size of the clogging zone, the increased in the clogging zone resulted in the decreased of exfiltration rate due to the accumulation of organic matters at the edge of the leakage area and trapped in the pores of the bedding soil

Renewable energy from biogas generated by sewage sludge: relationship between volume of sludge and volume of biogas / Aminuddin Muhamad Baki ... [et al.]

Biogas composed of methane and carbon dioxide is a by-product of anaerobic bacteria decomposition of organic waste which municipal garbage and sewage are important sources for biogas production. The methane content in the biogas enables it to be used as engine fuel and converted to heat and electricity. An experimental study that examined the relationship between organic content of sludge and methane generation as it progressed through mesophilic anaerobic digestion was completed. This case study is needed to determine organic content represented by BOD and SS in sewage, to quantify the biogas and methane generation from sewage sludge, to determine the relationship between organic content and volume of methane and also to determine the pressure of biogas and the relationship between sludge volume and volume of biogas. It was found that methane generation is potential during anaerobic digestion even with small volume of sludge. The quality of sludge for methane generation is dependent on the characteristics of sludge. Organic content characterized by Biological Oxygen Demand (BOD) and Total Suspended Solid (TSS) were measured in accordance to APHA standard methods (1998). Wastewater from two treatment plants namely, Kolej Mawar, UiTM and IWK WWTP Section 7, Shah Alam were used in this study. This study, found that higher organic content in sewage sludge will result in higher methane being generated

Electrophoretic deposition of adsorbed arsenic on fine iron oxide particles in tap water

Electrophoretic deposition (EPD) technique has been demonstrated to remove arsenic with natural adsorbent (fine iron oxide particles) in tap water samples. Characterizations of metal element particularly arsenic and fine iron oxide particles in tap water from two different locations, i.e. commercial and residential areas, were conducted. Results showed that the concentration of arsenic in tap water from residential area was higher than commercial area samples i.e. 0.022 ± 0.004 and 0.016 ± 0.008 ppm, respectively. The same finding was observed in zeta potential value where it was higher in the residential area than commercial area, i.e. −42.27 ± 0.12 and −34.83 ± 0.23 mV, respectively. During the removal of arsenic using the EPD technique, direct current (DC) voltage was varied from 5 to 25V at a constant electrode distance of 30 mm. Effect of zeta potential, voltage and electrode type were intensively investigated. High percentage removal of arsenic was obtained from carbon plate than carbon fibre electrode. The percentage removal of arsenic from all samples slightly decreased with increasing of the applied voltage. EDX analysis confirmed that arsenic has adsorbed onto deposited iron oxide particles on the anode electrode. Overall, EPD technique was found to be successful in removing arsenic onto fine iron oxide particles in tap water with 26% ± 1.05 of removal

Occurrence of thermophilic Campylobacter spp. contamination on vegetable farms in Malaysia.

The aim of the present study was to examine the prevalence of thermophilic Campylobacter spp. (Campylobacter jejuni and Campylobacter coli) in soil, poultry manure, irrigation water, and freshly harvested vegetables from vegetable farms in Malaysia. C. jejuni was detected in 30.4% and 2.7% of the soil samples, 57.1% and 0% of the manure samples, and 18.8% and 3% of the vegetable samples from farm A and farm B, respectively, when using the MPNPCR method. Campylobacter spp. was not found in any of the irrigation water samples tested. Therefore, the present results indicate that the aged manure used by farm A was more contaminated than the composted manure used by farm B. Mostly, the leafy and root vegetables were contaminated. C. coli was not detected in any of the samples tested in the current study. Both farms tested in this study were found to be contaminated by campylobacters, thereby posing a potential risk for raw vegetable consumption in Malaysia. The present results also provide baseline data on Campylobacter contamination at the farm level

Renewable energy from biogas generated by sewage sludge – relationship between sludge volume and power generated / Suzana Ramli ... [et al.]

Biogas is a product of decomposition of organic matter during the process of anaerobic digestion (AD). The main components are methane and carbon dioxide. The methane content in the biogas enables it to be used as fuel which can be converted to heat and electricity. The biogas generated by the anaerobic digesters has the potential to be redirected from the flaring facilities to renewable energy (RE) facilities. The biogas may then be used to generate electricity, which in turn can operate the sewage treatment plant (STP) itself. However, feedbacks from the sewerage industry indicated that heavy investments are needed for any RE initiatives on biogas generated by sewage sludge. In order to find the cost effective way of generating energy from biogas, fundamental relationships are necessary to enable development of prototype in the future. Thus, this paper presents a study to establish the relationship between the volume of sludge and the amount of power and energy that can be generated

Biosafety of Campylobacter jejuni from raw vegetables consumed as ulam with reference to their resistance to antibiotics

Antibiotic resistance in campylobacter is an emerging global public health problem after MRSA and VRE. Fluoroquinolone and macrolide resistance have been found to be more common in this world leading foodborne pathogen. A total of fifty-six isolates of Campylobacter jejuni obtained from raw vegetables which are consumed as ulam (salad) in Malaysia, were tested with 12 antibiotics used clinically and agriculturally. The resistance was determined using the disk diffusion method. Results were determined by hierarchic numerical methods to cluster strains and antibiotics according to similarity profiles. Fifty five C. jejuni isolates from different isolation sites were all clustered together into ten groups. This indicates that the commodities (raw salad vegetables/ulam) where the isolates originated might share a similar source of cross-contamination along the production route. All antibiotics tested correlated and there were four groupings reflecting their mode of actions. Generally, C. jejuni isolates were found to be highly resistant to erythromycin (91.1%) and tetracycline (85.7%). Both agents are popular antibiotics used clinically to treat bacterial infections. On the other hand, the C. jejuni isolates showed high percentage (80.4%) of resistance towards enrofloxacin, an extensively used antimicrobial agent in agriculture practices. This study showed that C. jejuni isolates were highly multi-resistance to as many as 10 antibiotics. Therefore, in terms of biosafety, the presence of antibiotic resistance strains in the food chain has raised concerns that the treatment of human infections will be compromised