Use of the standardized precipitation and evapotranspiration index (SPEI) from 1961 to 2019 to characterize the drought trend in northern Senegal: Study of the spatiotemporal dynamics in the Ferlo watershed

The study and analysis of the dynamics of the earth's climate is one of the scientific themes that has developed mostly at the recent years. This mobilized several scientists to study, describe or characterize the climate through several methods. These methods derived from climate science have given convincing results of high scientific significance, and above all through the appreciable quality of the indicators provided. In this context, and in order to appreciate this drought trend, we are using in the framework of this study of the Standardized Index of Precipitation and Evapotranspiration (SPEI) during the period 1961-2019. Indeed, the frequency and recurrence of drought are harmful events for the traditional production system in the Sahel region. Thus, the objective of this study is to identify the multiscale distribution of droughts. The results obtained define different types of droughts as well as their prevalence. These generally indicate the prevalence of slightly wet and slightly dry traits and are followed by moderately dry and moderately wet indices over all the stations studied. However, it should be noted a periodic occurrence of more or less long droughts which resulted in the preponderance of meteorological and agricultural droughts with occurrences mainly located in the periods 1974-1989 at Linguère station (1974-1989 and 1993- 2009), in Louga, between 1962-1973 and 1974-1982 in Podor, and, at the end between 1961-1970, 1974-1985 and 1993-2000 in Matam. In addition, the drought sequences are manifested earlier at the level of the stations of Matam and Podor. On other hand, at Linguère and Podor stations, the extreme drought indices were higher for all time scales chosen (SPI_1months, SPI_3 months and SPI_12 months).

Treatment of Oil from the Oil Industry Wastewater by the Production of a Hydrophobic Magnetic Polymer Nanocomposites

A novel, economic and environment-friendly composite material based on magnetic hollow magnetite (Fe3O4) nanoparticle coated with a polyvinyl pyrrolidone (PVP) was produced to treat the oil from the oil industry wastewaters. The oils were readily removed via hydrophobic PVP -magnetite nanocomposite. In this study the physicochemical properties of the produced PVP-magnetite nanocomposite were investigated with Fourier transform infrared spectrophotometer (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) analysis. The effects of increasing PVP -magnetite nanocomposite concentrations, the effects of separation time, effect of pH on the removal of oil were investigated. The removals of individual oil types with different carbon (C) ring numbers (from C 9 up to C 25) were investigated during oil removal. The reusing capacity of PVP-magnetite nanocomposite was investigated after 40 cycling for oil removal. The removal yields for all pollutants in the oil industry was investigated. FTIR analysis results showed that in the spectrum of PVP-coated magnetite nanocomposite the peak at 2500 1/cm can be attributed to the stretching vibration of C−N and C═O. XRD spectrum of the synthesized PVP– magnetite composite nanoparticle exhibited that the dominant phase of the composite nanoparticle is magnetite with a particle size of 16.8 nm. TGA analysis showed that about 69% weight loss was observed at 500°C and this is attributed to decomposition of PVP. Nonane (9 C rings) and undecane (11 C rings) have high removal yields like 99.99% while the oils with high carbon rings such as, 80% ducosene (22 C rings) and 72% pentacosane (25 C rings) exhibited low yields. The aforementined nanoparticle can be used 29 times to remove the oil with a yield of 99.99%. The maximum CODdis, COD, TSS and oil removal efficiencies were 99%, 99.5%, 99% and 99.90% respectively, via adsorption with 3 mg/l hydrophobic PVP-Fe3O4 / Polimer nanocomposite.

Overview of Biological Treatment Technologies for Greywater Reuse

Greywater is a wastewater discharge originating from kitchen sinks, showers, baths, washing machines and dishwashers. Properly treated greywater can be recycled to meet global water shortages that is expected to affect 2.7 billion people around the world by 2025. Global water shortage can result in a reduction in agricultural land and increased dissertation leading to poverty, faming, war, illegal migration and human trafficking. Greywater contains fewer pathogens than domestic wastewater, is generally safer to handle and easier to treat and reuse onsite for toilet flushing, landscape and crop irrigation. Recycling of grey water provides substantial benefits for both the water supply system by reducing the demand for fresh clean water, and for the wastewater system by reducing the amount of wastewater required to be conveyed and disposed of. In this paper, the existing biological treatment systems for greywater are reviewed. These are: (a) constructed wet land, (b) sequencing batch reactor, (c) vertical flow bioreactor, (d) membrane bioreactor, (e) up-flow anaerobic sludge blanket, (f) rotating biological contractors, (g) trickling filters, (h) aerated lagoons, (i) anaerobic up-flow filter, and (j) expanded bed up-floe reactor. In a biological treatment, the degradation and transformation of greywater constituents are facilitated by the biochemical reactions carried out by microorganisms in the liquid medium. However, the effluent of biologically treated greywater may contain pathogenic microorganisms, requiring a final disinfection step to eliminate the risk of contracting pathogenic diseases. Selection criteria for a disinfectant include: (a) non-toxicity to humans, domesticated animals, and aquatic ecosystems, (b) low cost (c) easy handling, (d) reliable analysis, and (e) a satisfactory residual concentration. Any disinfection process selected (whether chemical oxidants or irradiation treatment is selected) should be evaluated taken into consideration the conditions of the wastewater source and existing biological treatment design.

Environmental Performance Assessment of Batch Type Hot Mix Plant Using LCA

The environmental impacts from production of Hot Mix Asphalt (HMA) in batch Hot Mix Plant (HMP) has been evaluated using Life Cycle Assessment (LCA) methodology. The hot mix technology has been in use since long time for production of HMA used in construction of road pavements. The functional unit adopted is 100 tonnes of HMA production and CML 2001 method is used for assessment using GaBi 10.5. The study found that the production of HMA in batch HMP had very high environmental impacts on marine aquatic ecotoxicity potential (MAETP) impact category (8,25,573 kg DCB eq.), abiotic depletion fossil (ADP fossil) (2,87,295 MJ) impact category and global warming potential (GWP) impact category (2,770 kg CO2 eq.). The raw material phase had higher environmental impacts compared to production process phase on all the impact categories. It was also concluded that the use of renewable energy and fuel and adoption of cold mix technology will reduce the environmental impacts.

Concepts of bioremediation, bio augmentation and biosensors

Bioremediation uses microorganisms to destroy or immobilize waste materials. Microorganisms include archaea, bacteria, fungi and actinomycetes. Microorganisms destroy organic contaminants when they are using chemicals for their growth and reproduction. Although it is an old technique, it is still frequently used to remove environmental contaminants which have increased rapidly due to increased population, industrialization, and urbanization. There are various types of bioremediation, and different mechanisms associated with them. The process of bioremediation is enhanced by biostimulation. When bacterial culture is added to the contaminants to increase the rate of biodegradation, it is known as bio augmentation. Biosensors are devices used to detect the presence or concentration of a biological analyse, such as a biomolecule, a biological structure or a microorganism. This paper gives an idea of bioremediation, its scope, factors affecting bioremediation, types, biostimulation, bioaugmentation and biosensors.

System for detection of the inhomogeneous distribution of magnetic field based on liquid crystals with magnetic nanoparticle

The main objective of this article is to develop the basic technological principles of production of the magnetosensitive layer based on nematic liquid crystals with magnetic nanoparticles as the main component of the system, which allows obtaining a two-dimensional picture of the inhomogeneous distribution of low-frequency magnetic field and to identify the object creating this field. In work are described physical methods which allow to increase sensitivity and to expand a working frequency range of the magneto-sensitive layer based on such liquid crystals. By us it has been shown, that the time of reorientation of director in oriented liquid crystals with magnetic nanoparticles is less than the analogous reorientation time in nonoriented crystals. In work also it is shown, that to significantly increase the speed of reorientation in a magnetic field of the director of liquid crystals with magnetic nanoparticles is possible if submitting an additional magnetic field with given amplitude. This method allows to increase sensitivity to a magnetic field and to receive parametrical amplification of signals in liquid crystals with magnetic nanoparticles. In the conclusion on the basis of liquid crystals with magnetic nanoparticles the scheme of system of detection of inhomogeneous magnetic field is described.

Chemical, Physical and Biological Carwash Wastewater Treatments for Water Recycling: Critical and Comparative Analyses

The carwash industry uses large volumes of freshwater and release wastewater containing harmful chemicals into the environment. The type and quantity of cleaning chemicals and finish products used and the amount of dirt present on the vehicle affect the physical, chemical and biological characteristics of the carwash wastewater. The growing public concerns for water conservation and the environmental health of water waterways has led to several environmental regulations to encourage wastewater reclamation and reduction of pollution loads. The environmentally friendly carwash operation requires a good washing technology with compatible washing chemicals and advanced water treatment methods with proper water recycling system. The desire of professional carwash operators to conserve water and/or reduce discharges dictate the choice of approach and reclaim equipment to be installed. This study describes the treatment options for carwash wastewaters for recycling in order to achieve pollution reduction, water conservation and economic benefits for carwash operators. These treatments include chemical coagulation-flocculation, electrocoagulation, electrooxidation, granular filtration, microfiltration, ultrafiltration, nanofiltration, reverse osmosis, biofilters, bioreactors, wetlands and adsorption. The advantages and disadvantages of each method were determined. Each method was evaluated and compared with other methods using a standard set of criteria that included: cost, maintenance and control, efficiency, suitability, value added product, environmental and health impact and size and land requirement. These criteria were developed based of the advantages and disadvantages of the treatment methods. Each criterion was assigned a score based on its relative importance. A comparative analysis was performed on the 12 methods of carwash wastewater treatments using the eight criteria. The results indicated that granular filter treatment had the highest score (87) followed by reverse osmosis (84). It is therefore recommended that a combination of granular filter and reverse osmosis be used to treat carwash wastewater. The granular filter is used as a pre-treatment option to remove suspended solids, heavy metals and pathogenic microorganisms and the reverse osmosis unit is used as a final treatment for polishing the granular filter effluent and remove all remining organic molecules, cysts, bacteria, virus and all minerals including dissolved individual ions. The final product is a spotfree rinse water resulting in glass, chrome, and all painted surfaces to dry spot-free. Granular filter is easy to set up using locally available material, is economical and has a low capital and operating cost and a short residence time and can achieve reductions of up to 100% of COD, TSS and turbidity. Reverse osmosis results in complete removal of pathogens and virus and up to 99 % removal of dissolved solids.

Greywater Sources, Characteristics, Utilization and Management Guidelines: a review

Greywater is defined as a domestic wastewater that is uncontaminated by direct contact with human excreta. Sources of grey water include kitchen sinks, showers, baths, washing machines and dishwashers. Most greywater streams produce effluents high in dissolved contaminants and low in turbidity and suspended solids. As global water resource supplies are worsening and water shortages will affect 2.7 billion people by 2025, resulting in poverty and famine. Reusing greywater is a good way to solve this water shortage problem. As greywater contains fewer pathogens than domestic wastewater (black water), it is safer to handle, easier to treat and reuse onsite for toilet flushing and landscape or for crop irrigation and other non-potable uses. Greywater use in gardens or toilet systems helps to achieve some of the goals of ecologically sustainable development including: (a) reduced freshwater extraction from rivers and aquifers, (b) less impact from septic tank and treatment plant infrastructure, (c) reduced energy use and chemical pollution from treatment plants, (d) groundwater recharge and (e) reclamation of nutrients. However, the biological oxygen demand (BOD), surfactants, oil and grease, detergent residues (nitrogen, phosphorous, sulfate, ammonium, sodium, and chloride) must be considered when handling greywater streams. Several countries have developed guidelines for the reuse of treated greywater to flush toilets and irrigation systems for ornamental garden and lawn watering, depending on the type of grey water and treatment level. Many developed and developing countries have established regulations and guidelines for greywater treatment and reuse. However, some countries have strict rules compared to others. Egypt appears to be a world leader in the treatment and reuse of wastewater and has several laws in place for treatment options and selection of crops to be irrigated with treated wastewater. Given the water shortage in Egypt and the growing population, the government of Egypt imparked on several mega projects of 4-level wastewater treatment throughout the country for use in agricultural production.

Removal of polyaromatics from textile industry using La /ZnO nanocomposite

The effects of the type and amount of loadings on the photocatalytic activity of Ln/ ZnO were studied and the results were compared with pure ZnO. The textile wastewaters (TW) could not be treated effectively with concentional treatment processes due to high polyphenols and colour content. In this study, La/ZnO nanocomposite was used for the photocatalytic oxidation of pollutant parameters [COD components (CODtotal, CODdissolved, CODinert), polyaromatic amines and color] from the textile effluent wastewaters (TW) at different operational conditions such as, at increasing photooxidation times (5 min, 15 min, 30 min, 60 min, 80 min and 100 min), at diferent La mass ratios (0.5wt% , 1wt%, 1.5wt%, 2wt%), at different La-ZnO photocatalyst concentrations (1, 5, 15, 30 and 45 mg/L), under 10, 30, 50 and 100 W ultraviolet (UV) irradiations, respectively. The maximum CODtotal, CODinert, total aromatic amines (TAAs) and color photooxidation yields were 99%, 92%, 98% and 99% respectively, under the optimized conditions, at 30 mg/L La/ZnO nanocomposite with a La mass ratio of 1.5 wt% under 50 W UV light, after 60 min photooxidation time, at 25oC. The photooxidation yields of 2-methoxy-5-methylaniline (MMA), 2,4-diaminoanisole(DAA); 4,40-diamino diphenyl ether (DDE), o-aminoazotoluene (OAAT), and 4-aminoazobenzol (AAB) polyaromatic amines were > 82%. The pollutants of textile industry wastewater were effectively degraded with lanthanum doped ZnO nanocomposite.

Utilization of Waste Paper to Manufacture of Hydrogels

Huge volumes of mixed waste paper (MWP) pollute the environment. Nevertheless, it is an abundant, renewable and inexpensive material, so finding a new way of utilization it is very important. In this article, MWP has been used as initial material for the production of hydrogels. It was found that when MWP is treated with a cold solvent, namely with an aqueous solution of 7%NaOH/12%Urea (N/U), at solvent to initial paper ratio R ≥ 5, complete amorphization of the cellulose component of the paper occurs, as a result of which a hydrogel is formed. In addition, if the alkali of the solvent is neutralized with phosphoric acid, then the resulting hydrogel will contain PN-fertilizer and can be applied in agriculture. Studies have shown that this hydrogel promotes seed germination, increases the water retention of the soil, and then completely decomposes in a short time under the action of enzymes secreted by microorganisms present in the soil.