Current Environmental Management (Formerly: Current Environmental Engineering) - Volume 6, Issue 3, 2019

Removal of heavy metals is very important in wastewater treatment process, due to their abundant hazardous effects. There are various chemical and physical methods including ion exchange, reverse osmosis, electrodialysis, and ultrafiltration for removing heavy metals from wastewater, but biological treatment has attracted researchers for years as it is cheap and efficient. Microalgae have a significant capability of absorbing and eliminating heavy metals from wastewater. One of the most attractive microalgae species for this application is the Chlorella vulgaris Beijerinck. The current study takes a literature review of using microalgae species, especially C. vulgaris, with the aim of wastewater heavy metal treatment. In this regard firstly, various methods of eliminating heavy metals using microalgae were investigated, and then the application of C. vulgaris in the process of eliminating heavy metals from wastewater is fully presented. It became obvious that the use of C. vulgaris application is more helpful in the case of Copper, Lead, Zinc, Cadmium, and Nickel. Moreover, the main factor affecting heavy metal treatment using C. vulgaris is the pH of media, and the second effective parameter is temperature that is often considered about 25°C. The appropriate time period for the treatment was 5-7 days. Generally, C. vulgaris presented a very favorable efficiency in eliminating various heavy metals and is capable of removing heavy metals from wastewater to more than 90% on average.

Background: Ultrafiltration membrane processes have become an established technology in the treatment and reuse of secondary effluents. Nevertheless, membrane fouling arises as a major obstacle in the efficient operation of these systems. Aim/Objective: This study evaluates the factors affecting pretreatment conditions for combination ultrafiltration membrane processes for reuse of secondary effluent from the sewage treatment plant. The objective of this work is to study the precoagulation effect on the removal of organic matter from secondary effluent from the wastewater treatment plant Reghaïa (Algiers) and for fouling of the membranes ultrafiltration. Methods: A comparison was made between two coagulant FeCl3 and Fe2(SO4)3 using two processing systems, Coagulation (with sedimentation) / Ultrafiltration and Coagulation (without sedimentation) / Ultrafiltration. The optimum conditions for coagulation were determined by the analysis UV254 and turbidity. Result: The results showed that there's a better reduction of the decrease of permeate flux (Jv) in the coagulation system (without sedimentation)/Ultrafiltration for both coagulants because of trapping of organic molecules responsible for fouling of the membrane inside the porous flocs formed in the coagulation.

Objective: This paper uses the Analytic Hierarchy Process (AHP) to rank main actions and their associated task areas outlined in the Hyogo Framework for Action (HFA) in the case of Nigeria. The focus is on three major challenges namely (1) stakeholder inclusiveness, (2) capacity building and communication and (3) local adaptation. Methods: The perceptions of a sample of 26 field disaster management experts on the HFA were studied and analyzed using AHP. The study found that "Disaster Preparedness" is the most important expected goal followed by "Risk Assessment and Early Warning." Results: Their priority indices are 0.258 and 0.219, respectively. "Local/City Governance" however, shows poor performance with a priority index of 0.085. Monte Carlo simulation was further applied to examine the robustness of the AHP assessments. Conclusion: The results are indicative of the perceptions of the performance levels attained and the areas that need improvement.

Background: The São Paulo State area has been facing a water crisis that caused water shortage in many cities, and a series of socioeconomic problems as an outcome. Water supply massive land-use alteration throughout São Paulo State river basins, coupled with climate change effects might produce severe damage to the region if preventive actions are not enforced in time. Objective: This study aims to apply an adapted methodology of fragility analysis to a tributary of the Itupararanga reservoir (Brazil) using a hydrological modeling tool. Based on the determination of the flow and drainage system direction and object-based image analysis, a final map of the fragility will be constructed. Methods: This paper presents a fragility assessment methodology on a local scale using a rural watershed of the study area. This approach uses object-based classification of topography data from Shuttle Radar Topography Mission to extract the most fragile territorial units of the watershed area, in terms of pollution and siltation contribution risk, combined with land cover classification. Results: The study area exhibits very high and medium fragility areas related to water contamination and siltation risk that can be seen as priority areas for land cover management and monitoring, although most of the basin area was classified as very low fragility. Conclusion: The methodology applications have great potential uses in territorial planning, protected areas and restoration priorities delimitation, ecological-economic zoning, hazard evaluation and mitigation, erosional processes and water protection and management at both local and regional scale studies.

Background: The study was conducted in-situ at the INCA Pond system in the City of Boynton Beach, Florida which has experienced issues with the formation of harmful algae blooms that create nuisance complaints and unhealthy conditions in the water and surrounding area. Objective: The EMOH device is designed to supersaturate water as a means to deter harmful algal blooms. This pilot study was conducted to determine if an Electromagnetic Hydrolysis (EMOH) device can improve the health of residential surface water by adding dissolved oxygen to the water to allow the existing bacteria to remove the substrate that provides a food source for blue-green algae outbreaks when combined with naturally occurring aerobic bacteria. Methods: Combining the EMOH device with naturally occurring aerobic bacteria demonstrated that a pond that normally contained a low DO and copious amounts of algae, would contain fewer algal blooms, that the bacteria would consume the detrital layer on the bottom of the pond that acts as nutrient source for the algae and that DO levels increase with temperature, in contrast to expectations. Four configurations were compared. Results: The EMOH device successfully reduced the detrital layer on the bottom of the pond and experienced fewer algal blooms. The use of surface aeration permits the oxygen to escape, so having the EMOH discharge below the surface increases efficiency. Conclusion: The EMOH device successfully accomplished its intended goals.

Aims: To understand the links between climate variability and hydrology in western Libya. Background: This study represents the first comprehensive assessment of rainfall variability in western Libya at a regional scale. Objective: To assess temporal and spatial variability of rainfall in western Libya, based on data (1979-2009) from 16 rain gauges. Methods: The non-parametric Mann-Kendall method and Sen’s slop estimator were used to define changes in rainfall series and their statistical significance. Results: Coastal and mountainous time series showed decreasing trends at the annual, autumn, and spring scales, with very few exceptions. Notably, winter showed increasing trends, with the significant values of 1.94 and 0.88 mm/year at Sirt and Nalut, respectively. Desert stations showed increasing trends, especially at the annual scale, with the greatest significant increase on the order of 1.19 mm/year in Ghadames. For the regional rainfall trend analysis, annual, spring and autumn rainfalls decreased in the coastal and mountainous zones, with the highest significant decrease of 1.94 mm/year. Again, winter rainfall showed increasing trend over the whole study domain. Conclusion: Although most time series showed a tendency towards more drier conditions, most of the detected trends were statistically non-significant. This study will provide guidance for policy makers in their future planning to mitigate the impact of drought.

Background: Dyes are used in various sectors, such as the industry, textile, leather, and plastic industries, and part of these dyes is released in the environment via wastewater. Objective: The present study aimed to investigated the surface-modified TiO2 by MoS2 and Cu. Method: The effects of surface enhancement on as-prepared adsorbents on adsorption of Methylene Blue (MB) was were studied in a batch system by considering various parameters such as contact time, initial dye concentration and temperature. Result: The results show that the adsorption process was well fitted with the pseudo-firstorder kinetic model (R2 = 0.99). Further, the equilibrium data for the adsorption process have beenwere evaluated using Langmuir, Freundlich, and Temkin isotherms. Conclusion: The adsorption isotherm of MB onto as-prepared adsorbents nanoparticles fitted into the Freundlich equation.