Biotechnological Potentials of Microbe Assisted Eco-Recovery of Crude Oil Impacted Environment

Globally, the environment is facing a very challenging situation with constant influx of crude oil and its derivatives due to rapid urbanization and industrialization. The release of this essential energy source has caused tremendous consequences on land, water, groundwater, air and biodiversity. Crude oil is a very complex and variable mixture of thousands of individual compounds that can be degraded with microbes with corresponding enzymatic systems harboring the genes. With advances in biotechnology, bioremediation has become one of the most rapidly developing fields of environmental restoration, utilizing microorganisms to reduce the concentration and toxicity of various chemical pollutants, such as petroleum hydrocarbons, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, phthalate esters, nitroaromatic compounds and industrial solvents. Different remediation methods have been introduced and applied with varied degrees of success in terms of reduction in contamination concentration without considering ecotoxicity and restoration of biodiversity. Researchers have now developed methods that consider ecotoxicology, environmental sustainability and ecorestoration in remediation of crude oil impacted sites and they are categorized as biotechnological tools such as bioremediation. The approach involves a natural process of microorganisms with inherent genetic capabilities completely mineralizing/degrading contaminants into innocuous substances. Progressive advances in bioremediation such as the use of genetically engineered microbes have become an improved system for empowering microbes to degrade very complex recalcitrant substances through the modification of rate-limiting steps in the metabolic pathway of hydrocarbon degrading microbes to yield increase in mineralization rates or the development of completely new metabolic pathways incorporated into the bacterial strains for the degradation of highly persistent compounds. Other areas discussed in this chapter include the biosurfactant-enhanced bioremediation, microbial and plant bioremediation (phytoremediation), their mechanism of action and the environmental factors influencing the processes.

Persistence of SARS-CoV-2 virus and viral RNA in relation to surface type and contamination concentration

The transmission of SARS-CoV-2 is likely to occur through a number of routes, including contact with contaminated surfaces. Many studies have used RT-PCR analysis to detect SARS-CoV-2 RNA on surfaces but seldom has viable virus been detected. This paper investigates the viability over time of SARS-CoV-2 dried onto a range of materials and compares viability of the virus to RNA copies recovered, and whether virus viability is concentration dependant. Viable virus persisted for the longest time on surgical mask material and stainless steel with a 99.9% reduction in viability by 122 and 114 hours respectively. Viability of SARS-CoV-2 reduced the fastest on a polyester shirt, with a 99.9% reduction within 2.5 hours. Viability on the bank note was reduced second fastest, with 99.9% reduction in 75 hours. RNA on all the surfaces exhibited a one log reduction in genome copy recovery over 21 days. The findings show that SARS-CoV-2 is most stable on non-porous hydrophobic surfaces. RNA is highly stable when dried on surfaces with only one log reduction in recovery over three weeks. In comparison, SARS-CoV-2 viability reduced more rapidly, but this loss in viability was found to be independent of starting concentration. Expected levels of SARS-CoV-2 viable environmental surface contamination would lead to undetectable levels within two days. Therefore, when RNA is detected on surfaces it does not directly indicate presence of viable virus even at high CT values. Importance This study shows the impact of material type on the viability of SARS-CoV-2 on surfaces. It demonstrates that the decay rate of viable SARS-CoV-2 is independent of starting concentration. However, RNA shows high stability on surfaces over extended periods. This has implications for interpretation of surface sampling results using RT-PCR to determine the possibility of viable virus from a surface, where RT-PCR is not an appropriate technique to determine viable virus. Unless sampled immediately after contamination it is difficult to align RNA copy numbers to quantity of viable virus on a surface.

Persistence of SARS-CoV-2 virus and viral RNA on hydrophobic and hydrophilic surfaces and investigating contamination concentration

The transmission of SARS-CoV-2 is likely to occur through a number of routes, including contact with contaminated surfaces. Many studies have used RT-PCR analysis to detect SARS-CoV-2 RNA on surfaces but seldom has viable virus been detected. This paper investigates the viability over time of SARS-CoV-2 dried onto a range of materials and compares viability of the virus to RNA copies recovered, and whether virus viability is concentration dependant. Viable virus persisted for the longest time on surgical mask material and stainless steel with a 99.9% reduction in viability by 124 and 113 hours respectively. Viability of SARS-CoV-2 reduced the fastest on a polyester shirt, with a 99.9% reduction within 2.5 hours. Viability on cotton was reduced second fastest, with 99.9% reduction in 72 hours. RNA on all the surfaces exhibited a one log reduction in genome copy recovery over 21 days. The findings show that SARS-CoV-2 is most stable on non-porous hydrophobic surfaces. RNA is highly stable when dried on surfaces with only one log reduction in recovery over three weeks. In comparison, SARS-CoV-2 viability reduced more rapidly, but this loss in viability was found to be independent of starting concentration. Expected levels of SARS-CoV-2 viable environmental surface contamination would lead to undetectable levels within two days. Therefore, when RNA is detected on surfaces it does not directly indicate presence of viable virus even at high CT values.

Macrophyte Potential to Treat Leachate Contaminated with Wood Preservatives: Plant Tolerance and Bioaccumulation Capacity

Pentachlorophenol and chromated copper arsenate (CCA) have been used worldwide as wood preservatives, but these compounds can toxify ecosystems when they leach into the soil and water. This study aimed to evaluate the capacity of four treatment wetland macrophytes, Phalaris arundinacea, Typha angustifolia, and two subspecies of Phragmites australis, to tolerate and treat leachates containing wood preservatives. The experiment was conducted using 96 plant pots in 12 tanks filled with three leachate concentrations compared to uncontaminated water. Biomass production and bioaccumulation were measured after 35 and 70 days of exposure. There were no significant effects of leachate contamination concentration on plant biomass for any species. No contaminants were detected in aboveground parts of the macrophytes, precluding their use for phytoextraction within the tested contamination levels. However, all species accumulated As and chlorinated phenols in belowground parts, and this accumulation was more prevalent under a more concentrated leachate. Up to 0.5 mg pentachlorophenol/kg (from 81 µg/L in the leachate) and 50 mg As/kg (from 330 µg/L in the leachate) were accumulated in the belowground biomass. Given their high productivity and tolerance to the contaminants, the tested macrophytes showed phytostabilization potential and could enhance the degradation of phenols from leachates contaminated with wood preservatives in treatment wetlands.

Transport of Contamination under the Influence of Sea Level Rise in Coastal Heterogeneous Aquifer

This paper provided for the first time an experimental study on the influence of sea level rise on transport of contamination in the heterogeneous unconfined aquifer of the coastal zone. The experiments were conducted using the tank, considering the difference between sea level and inland head 1 cm for Case 1 and 2 cm for Case 2. Observed data were validated using the numerical model, which matched well with the toe length of seawater wedge and the shape of the contaminant plume. The results showed that the observed and simulated values of Cl− concentration at the sampling points increased sharply at the initial time, and then they increased slowly and tended to be stable. The seawater wedge migrated inland with time under the effects of the hydraulic gradient toward the inland and the density difference between saltwater and freshwater. The steady state length of the 50% isoline of the seawater wedge was 167 cm in Case 2, which was larger than that of Case 1. The maximum area of plume in Case 2 was 0.13 m2, larger than that in Case 1, which indicated that the velocity of diffusion of the contaminant plume increased as the sea level increased. As the velocity of diffusion increased, the time for pollutant migration to the intersection between seawater and freshwater became shorter. The maximum area and vertical depth of pollutant plume were sensitive to the hydraulic conductivity, dispersivity, and contamination concentration. The infiltration depth and range of the contaminant plume in the heterogeneous aquifer were greater than those in the homogeneous aquifer of the actual beach.

Outdoor transportation of influenza virus under natural wind field

The transportation of influenza virus in a group of buildings under the condition of natural wind field was studied. The curves of natural wind power spectrum and the velocity field with respect to time were simulated by the improved weighted amplitude wave superposition with fast Fourier transform. According to Davenport spectrum, the approximation function of wind velocity field with respect to time was used to simplify the calculation efforts. The average wind field and natural wind field were adopted to simulate the microbial contamination diffusion in a group of buildings. In the case of natural wind, the virus particles are dispersed faster from buildings, and the contamination concentration is low. However, the large downwind area may face the threat of virus contamination.

FIELD PILOT STUDY ON THE ASSESSMENT OF SELECTED HYDROCARBON REMEDIATION TECHNIQUES

The study discussed the remediation potentials of phytoremediation, land farming treatment and chemico-biological stabilization treatments in degrading Total Petroleum Hydrocarbon (TPH) and Polycyclic Aromatic Hydrocarbon (PAH) in soils polluted with crude oil in varying concentrations. The field pilot study was carried out in Benin city, Nigeria by preparing nine (9) cells with sub-cells attached which serve as control; each cell measures 1.53 m2. Three cells contained 100 kg of artificially contaminated soils at low contamination concentration (3000 mg kg-1), the next three cells contained 100 kg of contaminated soil samples but with medium concentration (5000 mg kg-1), while the last three cells contained 100 kg of spike samples in high concentration (7000 mg kg-1). The sub cells contained 10 kg of soil and left untreated. Each role containing three cells with low, medium and high concentration was treated separately using the three treatment methods. Soil samples to organic amendment ratio for the treatments was 2:1. The results showed over 90% reduction in the initial concentration of TPH and PAH across the different contamination levels with except in the control sub cells were only 30% reduction was recorded. The treated soil was found useful for agricultural purpose. One-way analysis of variance reveals a significant difference at p≤0.05 in the results obtained in application of the three methods. This implies that the methods effectively degraded the TPH and PAH concentrations. The three different methods of treatments effectively degraded TPH and PAH contaminants with land farming treatment being the best of the three.

COMPARATIVE ANALYSIS OF THE ACCUMULATION OF HEAVY METALS IN MUSCLES OF HYDROBIONES OF THE SHEREPOK RIVER (VIETNAM)

The paper presents analysis of heavy metals concentration in the muscles of hydrobionts in the Sherepok River. In particular, there was studied the content of zinc, copper, iron, cadmium, lead, arsenic in the muscles of hemibagrus ( Hemibagrus wyckioides ) , carp ( Cyprinus carpio ) and tilapia ( Oreochromis niloticus ), river crab ( Somannia thelphusa sinensis ) and river snail ( Pomacea canaliculata ), which were caught in the river segments with different degrees of heavy metal contamination. Concentration of heavy metals in muscles of hydrobionts was tested in four river segments: upper the border of the industrial zone, within the borders of industrial zone Khoa Fu, lower the border of industrial zone Tam Thang, and in the reservoir zone Sherepok 3. It has been found that in all segments of the Sherepok river, regardless of the degree of contamination, most zinc concentration was encountered in the body of the river snail, lead - in the muscles of hemibagrus. Copper and cadmium are most abundant in the body of the river snail in all the research areas, except for the reservoir zone Sherepok 3, where the largest amount of these metals was registered in the muscles of carp. Arsenic accumulates in the largest amount in the muscles of hemibagrus, although in the zone of the greatest pollution of the river (within the boundaries of the industrial region), its muscles contain the least amount of arsenic, compared to other hydrobionts under study.