High Pollution Potential Research Articles

A GIS-based groundwater pollution potential using DRASTIC, modified DRASTIC, and bivariate statistical models.

The objective of the current study is groundwater vulnerability assessment using DRASTIC, modified DRASTIC, and three statistical bivariate models (frequency ratio (FR), evidential belief function (EBF), and weights-of-evidence (WOE)) for Sari-Behshahr plain, Iran. A total of 218 wells were sampled for nitrate concentration measurement in 2015. Datasets were generated using results from 109 wells having nitrate concentrations greater than 50 mg/L. The nitrate data were divided into two groups of 70% (76 locations as training dataset) for modeling and 30% (33 locations as a testing dataset) for model validation. Finally, five groundwater potential pollution (GPP) maps were produced by the training dataset and then evaluated using the testing dataset and receiver operating characteristic (ROC) method. Results of the ROC method showed that the WOE model had the highest predictive power, followed by EBF, FR, modified DRASTIC, and DRASTIC models. Results of the maps obtained revealed that high and very high pollution potential covered the southern part of the study areas, where big cities are located. Results of the present study can be replicated in other locations for identifying groundwater contaminant prone areas.

Application of MCLP and LINGO methods to optimal design of groundwater monitoring network in an oil refinery site

Abstract Groundwater-monitoring network is a set of boreholes (wells) that is used to monitor the water table fluctuation and to detect groundwater contamination. In this research, the maximal covering location problem (MCLP) method is employed to discretize the area, and the LINGO modeling program is used to optimize the number of boreholes. Tabriz oil refinery at the northwest of Iran with high pollution potential that imposes a serious threat to the beneath multilayered aquifer was chosen to evaluate the feasibility of these techniques in field scale. The location and content of storage tanks, leakage history, groundwater flow direction, contaminated well location and the facilities leakage potential are considered as the weighting factors to calculate the number and location of the optimal wells. As a result of optimization, the initial estimated number of boreholes by the MCLP model for the study area is reduced from 349 to 184. A high density of optimal boreholes is allocated to refining zone and oil storing yard, especially near tanks containing dangerous substances due to their toxicity and potential for contaminating water. A vulnerability zoning map prepared using the analytical hierarchy process method indicates a suitable conformation between locations of the boreholes and the vulnerable areas.

Characteristics of indoor air pollutants and estimation of their exposure dose

Rural areas of developing countries have various indoor air pollution sources along with solid fuels used for cooking. This study aims to compare five indoor air pollution sources, viz., incense stick, dhoop, mosquito coil, cigarette, and cooking fuel charcoal, with respect to their pollution potential. The monitoring of PM, CO, CO2, NO2, and particulate bound heavy metals was carried out. Dhoop (DH1) was found to be emitting the highest concentration of metal Sb among all the analyzed metals. Dhoop, incense sticks, mosquito coil, and charcoal were found to be having high pollution potential. The first-order decay rate equation indicated that the highest decay rate constant per hour was observed with dhoop (DH1) for PM10 and PM2.5 and with mosquito coil (M1) for CO. The highest half-life of PM10 and PM2.5 was observed for cigarette (CG1) and charcoal (C1) respectively indicating their slow decay in air. The average daily dose values indicated that the age group 6 to < 11 years, 11 to < 16 years, and 31 to < 51 years will be more vulnerable to PM emissions from dhoop (DH1) and incense stick (IS1). The highest hazard index was estimated for incense stick (IS1) and charcoal. Significant carcinogenic risk was observed from cigarette and charcoal. The multiple-path particle dosimetry (MPPD) model was used to estimate the deposition of PM fractions in various regions of the human body.

Anaerobic digestion of dairy wastewater: effect of different parameters and co-digestion options—a review

Increasing demand for dairy products resulted in the development of a large number of dairy industries, generating wastewater of high pollution potential. Main wastes generated include whey residues, milk fat and proteins, dairy sludge, and liquid effluents produced through different lines (cleaning, processing, and sanitary). Anaerobic digestion technology has got wide acceptance in recent times for treating highly organic effluents like dairy wastes due to its added benefits like energy recovery and high waste stabilisation with less energy requirement. This review paper is aimed at studying the effects of different key parameters (pH, carbon-to-nitrogen ratio, temperature, organic loading rate, solid retention time, hydraulic retention time, alkalinity, and mixing) on the successful operation of an anaerobic digester and thereby enhancing biogas production efficiency. Different waste streams generated in the dairy industry are identified along with their important characteristics. The process chemistry of anaerobic degradation of various effluents generated from the dairy industry is discussed. The need for pre-treatment technologies and the scope of co-digestion of dairy wastewater with other organic wastes are also covered. This critical review is intended to summarise the present knowledge on the application of anaerobic methods for treating dairy wastes most efficiently with proper control over operational parameters while maximising the biogas yield.

Adsorption kinetics of Remazol Brilliant Blue R dye from liquid effluents by bovine bone charcoal

The textile industry stands out for generating effluents with high levels of dyes, which have a high polluting potential. Among these dyes, the Remazol Brilliant Blue R azo dye, is one of the most used for dyeing wool and cotton, being released in excess on these effluents. Intended for the carcinogenic and mutagenic potential of this type of dyes, several researches are developed in search of economical technologies for their removal. An adsorption is a viable technique, since several materials can be used for this purpose. Bovine bone activated carbon, as it is a residue from the livestock industry that is easily obtained, has been studied as an adsorbent material in the removal of dyes. Therefore, the objective of this project was to evaluate the performance of the adsorption kinetics of the Remazol Brilliant Blue R dye from the effluents using bovine bone activated carbon. The experiments were carried out in batches, with solutions concentrations of 20, 50 and 100 ppm, and the mathematical models of pseudo-first order, pseudo-second order and intraparticle diffusion were adjusted to the experimental data. For concentrations of 20 and 50 ppm, the model that best fits was the pseudo-first order, while for the concentration of 100 ppm the pseudo-second order model obtained the best result with R2 of 0.992. The intraparticle diffusion model showed that the higher the concentration of the dye in solution, the greater the thickness of the boundary layer and that the intraparticle diffusion does not control the adsorption process in any of the study criteria.

PRELIMINARY INVESTIGATION OF THE CHEMICAL COMPOSITION OF BALLAST WATER AND TANK SEDIMENTS OF SELECTED SHIPS WITHIN THE LAGOS HARBOUR, NIGERIA

Ballast water is important for safe and efficient operation of vessels, helping to maintain stability during voyage in seas and docking in harbours. However, ballast water can pose considerable environmental challenges because they are often laden with polluted sediments and invasive species. The Lagos Harbour, which houses in the largest port in West Africa, receives about five thousand vessels annually which discharge ballast water and tank sediments into the water with the potential to cause environmental pollution. In the Nigerian context there is high potential for pollution due to weak regulations, poor enforcement and limited research of this kind in order to understand their composition, fate and impacts. This study aims at characterizing the chemical composition (Heavy metals- Arsenic, Cadmium, Chromium, Copper, Lead &amp; Zinc, as well as carbon and nitrogen content) of the ballast water and the tank sediments because of their positive correlation with the survival of invasive species in the ballast water and tank sediments. Water samples were collected from four ships (2 cargos and 2 tankers) within the Lagos Harbour; surface (1-5 cm) sediment samples were scooped from ship tanks using a specialized grab for sampling ballast sediments. The sediments were transferred in specialized sample containers (cool boxes) to the University of Portsmouth in United Kingdom for analysis. Total metal concentrations were analysed using X-ray fluorescence (XRF). They were subjected to two acid digestions: Aqua regia (AR) and 1 M hydrochloric acid (1 M HCl) following the procedures set out by the Canadian National Water Research Institute (NWRI) and the United States Environment Protection Agency (US-EPA Method 3050B). Total carbon and nitrogen contents were determined using an in-line Yanaco MT-5 CHN analyser. The results obtained were compared with established guidelines and subjected to correlation and Principal Component Analysis (PCA). The findings indicated high concentrations of Nickel, Lead, and Zinc in the sediments with values of 59.6 mg/kg, 33.75 mg/kg and 43,145.7 mg/kg respectively which exceeded NOAA and CSQGs permissible standards. Tanker vessels contained relatively higher concentrations of the pollutants than cargo vessels. The findings from this study provide useful baseline data which will guide a more intensive investigation of the chemical composition of ballast water and tank sediments for effective comparison with what is obtainable elsewhere in the world. The maritime industry needs to pay close attention to ballast as a potential source of marine pollution particularly in developing countries like Nigeria where there is limited regulation for management of coastal areas with respect to shipping activities. The IMO needs to direct further effort at investigating the non-biological components of ballast water and sediments in order to protect valuable biodiversity. Keywords: Coastal Pollution, Ballast Water Management, Ships, Analytical Techniques

Effectiveness of Aeromonas hydrophila for the removal of oil and grease from cattle slaughterhouse effluent

Little is known about the use of microbial lipases for the treatment of beef industry effluent. It is essential to develop techniques for the sustainable management of this waste, given its high polluting potential, especially due to the high concentrations of oils and greases (O&G) present. Therefore, this study investigates the pretreatment of slaughterhouse effluent using lipase-producing microorganisms isolated from the waste itself. Firstly, a physicochemical characterization of the effluent was performed, followed by isolation and identification of a lipase-producing bacterium, which was used in a pretreatment step. A central composite rotational design (CCRD) was applied, considering the independent variables pH, temperature, and inoculum concentration, resulting in 17 assays, with lipolytic activity, O&G, and free fatty acids (measured during 72 h) as the response variables. The slaughterhouse effluent presented high polluting potential, with an O&G concentration of 2553.3 mg L−1 and COD of 8914.4 mg L−1. The isolated bacterium was identified as Aeromonas hydrophila. After 72 h of the experiment, lipolytic activity of 1.40 U mL−1, 59% O&G removal (pH: 7.0, temperature: 30.0 °C and inoculum concentration: 10%), and production of 36.0 μmol mL−1 of free fatty acids were obtained. It could be concluded that cattle slaughterhouse effluent is an excellent source of lipase-producing microorganisms and that the use of enzymes for the treatment of this waste is a promising technology.

Heavy metal pollution, ecological risk, spatial distribution, and source identification in sediments of the Lijiang River, China.

The Lijiang River is of great ecological and environmental importance for Guilin City, which is located in the karst area of southeast China. Given its importance, a detailed evaluation of the heavy metals (HMs) in the river sediment is required. For the first time, 61 sediment samples were collected along the entire Lijiang River to determine pollution level and ecological risk posed by 10 HMs (Co, Cr, Cu, Mn, Ni, Pb, Zn, As, Hg, and Cd). These were assessed using the geo-accumulation index, potential ecological risk index, and modified degree of contamination. The results showed that the mean concentrations of the majority of HMs exceeded their corresponding background values and followed the trend: midstream>downstream>upstream. Based on the spatial distributions and pollution indices of the 10 HMs, the Lijiang River was found to have a high accumulation of Cd, Hg, Zn, and Pb in the sediments. The midstream area was the most polluted with respect to Cd and Hg, and also posed a relatively higher potential ecological risk than the downstream and upstream areas. The sources of the assessed HMs were inferred based on a correlation analysis and principal component analysis, which identified both natural and anthropogenic sources. A higher pollution potential was associated with Cd, Hg, Pb, and Zn in the midstream and downstream areas due to higher organic and carbonate content, urbanization, agricultural activities, and leisure activities (e.g., boating and cruises). In contrast, natural erosion and weathering processes were responsible for the HM concentrations in the upstream area. The findings of this study will help the local authorities to protect the important water resource of the Lijiang River.

Comparison of landfill leachate generation and pollution potentials in humid and semi-arid climates

Climate conditions e.g., rainfall water are highly affecting landfill leachate generation and characteristics. This article aims to assess leachate generation and pollution potentials from landfills in different climate conditions, e.g., humid and semi-arid regions. Leachate volumes have been estimated by hydrologic evaluation of landfill performance (HELP) model, and the main water quality parameters and heavy metals were in-situ and laboratory analysed. Results of annual leachate generation rates per one ton of waste in humid and semi-arid landfill were 0.148 and 0.079 m3 respectively. However, leachate pollutants from humid landfill showed lower concentrations comparing with semi-arid landfill. This was reflected in LPI results of 25.1 and 29.5 for both landfills, respectively. These results concluded that semi-arid leachate gave lower generation rates and higher pollution potential than humid leachate, which can be revealed to the dilution effect of high rainfall levels in humid climates.

Non-methane hydrocarbon (NMHC) fingerprints of major urban and agricultural emission sources for use in source apportionment studies

Abstract. In complex atmospheric emission environments such as urban agglomerates, multiple sources control the ambient chemical composition driving air quality and regional climate. In contrast to pristine sites, where reliance on single or a few chemical tracers is often adequate for resolving pollution plumes and source influences, the comprehensive chemical fingerprinting of sources using non-methane hydrocarbons (NMHCs) and the identification of suitable tracer molecules and emission ratios becomes necessary. Here, we characterise and present chemical fingerprints of some major urban and agricultural emission sources active in South Asia, such as paddy stubble burning, garbage burning, idling vehicular exhaust and evaporative fuel emissions. A total of 121 whole air samples were actively collected from the different emission sources in passivated air sampling steel canisters and then analysed for 49 NMHCs (22 alkanes, 16 aromatics, 10 alkenes and one alkyne) using thermal desorption gas chromatography flame ionisation detection. Several new insights were obtained. Propane was found to be present in paddy stubble fire emissions (8 %), and therefore, for an environment impacted by crop residue fires, the use of propane as a fugitive liquefied petroleum gas (LPG) emission tracer must be done with caution. Propene was found to be ∼ 1.6 times greater (by weight) than ethene in smouldering paddy fires. Compositional differences were observed between evaporative emissions of domestic LPG and commercial LPG, which are used in South Asia. While the domestic LPG vapours had more propane (40 ± 6 %) than n-butane (19 ± 2 %), the converse was true for commercial LPG vapours (7 ± 6 % and 37 ± 4 %, respectively). Isoprene was identified as a new tracer for distinguishing paddy stubble and garbage burning in the absence of isoprene emissions at night from biogenic sources. Analyses of source-specific inter-NMHC molar ratios revealed that toluene/benzene ratios can be used to distinguish among paddy stubble fire emissions in the flaming (0.38 ± 0.11) and smouldering stages (1.40 ± 0.10), garbage burning flaming (0.26 ± 0.07) and smouldering emissions (0.59 ± 0.16), and traffic emissions (3.54 ± 0.21), whereas i-pentane ∕ n-pentane can be used to distinguish biomass burning emissions (0.06–1.46) from the petrol-dominated traffic and fossil fuel emissions (2.83–4.13). i-butane ∕ n-butane ratios were similar (0.20–0.30) for many sources and could be used as a tracer for photochemical ageing. In agreement with previous studies, i-pentane, propane and acetylene were identified as suitable chemical tracers for petrol vehicular and evaporative emissions, LPG evaporative and vehicular emissions and flaming-stage biomass fires, respectively. The secondary pollutant formation potential and human health impact of the sources was also assessed in terms of their hydroxyl radical (OH) reactivity (s−1), ozone formation potential (OFP; gO3/gNMHC) and fractional benzene, toluene, ethylbenzene and xylenes (BTEX) content. Petrol vehicular emissions, paddy stubble fires and garbage fires were found to have a higher pollution potential (at ≥95 % confidence interval) relative to the other sources studied in this work. Thus, many results of this study provide a new foundational framework for quantitative source apportionment studies in complex emission environments.

Reciclagem biológica do fósforo a partir do efluente suíno originário da biodigestão anaeróbia: uma revisão

O efluente suíno (ES) apresenta elevado potencial poluidor, pois, mesmo após o processo de biodigestão anaeróbia, contém ainda concentrações variáveis de nutrientes, especialmente de fósforo (P). Este trabalho teve como objetivo investigar por meio de uma revisão de literatura a reciclagem biológica do P como alternativa para o tratamento de ES originário da biodigestão anaeróbia. Observou-se que o processo denominado de remoção biológica reforçada de fosfatos consiste no método mais utilizado na remoção do P presente em efluentes. Ele consiste na ciclagem da biomassa através de ambientes aeróbios e anaeróbios e envolve a incorporação do P no interior da célula das bactérias e, a subsequentemente remoção da massa enriquecida com P no lodo. Apesar de existirem muitos aspectos a serem esclarecidos a respeito destas tecnologias, destaca-se que a reciclagem e a recuperação do P presente no ES representam importantes avanços na promoção da sustentabilidade no uso deste recurso que está ligado diretamente à segurança alimentar global.

Biodegradation of omethoate by Bacillus sp. YB-10: optimization of culture conditions and degradation characteristics

Omethoate is an acute organophosphorus pesticide which is widely used. It presents a high pollution potential and health risk nowadays. In this study, Bacillus sp. YB-10, which was isolated from the activated sludge of a pharmaceutical wastewater treatment plant, was used for degrading omethoate. The culture conditions and degradation characteristics were investigated. Results showed that the Bacillus sp. YB-10 could degrade omethoate through co-metabolism. The optimal carbon and nitrogen sources were glucose and NH4NO3, respectively. Response surface methodology (RSM) results showed that the most appropriate nutrition ratio of C:N:P was 3:1:1 when degrading 1,000 mg/L of omethoate. Omethoate degradation kinetics could be described by a first-order rate equation. The optimal degradation conditions were pH of 7.0, temperature of 30℃, initial bacteria concentration of 0.25%, rotation speed of 150 r/min. Under the optimal conditions, the degradation rate reached 77.24% within 5 d by the Bacillus sp. YB-10 when the initial omethoate concentration was 1,000 mg/L.

Determining the lake protected zones using GIS-based DRASTIC model to groundwater vulnerability in Salda Lake basin (Burdur/Turkey)

Groundwater quality is a crucial parameter for sustainable wetland management. The evaluation of the aquifer vulnerability is important for the protection of groundwater resources. The DRASTIC model is the most significant technique for the assessment of aquifer vulnerability. This study aimed to build a vulnerability map for groundwater of the Salda Lake wetland basin by DRASTIC method in a GIS environment. Seven environmental parameters (depth to water table, net recharge, aquifer media, soil media, topography, impact of the vadose zone media, and hydraulic conductivity of the aquifer) were used in the DRASTIC method and GIS was used to constitute a groundwater vulnerability map. This study showed that 13.71% of the area had high pollution potential, 10.13% had moderate pollution potential, and 76.15% had low pollution potential in respect to groundwater pollution. Intensive agricultural activities are carried out in the study area. The DRASTIC vulnerability index value of the study area was well correlated with the nitrate map of the study area. In addition, Salda Lake protection areas were determined. All of the defining protection areas of the Salda Lake are within the most sensitive areas in DRASTIC map.

Hyperspectral field spectroscopy and SENTINEL-2 Multispectral data for minerals with high pollution potential content estimation and mapping

Mining in Tunisia generates a large amount of tailings charged with toxic minerals. As these tailings have a wide spread distribution, it is important to characterize and estimate their impact on soil contamination. This study examines the potential of field hyperspectral spectroscopy and SENTINEL-2 Multispectral data in estimating and mapping seven minerals content, including three toxic minerals (fluorite, barite and sphalerite), within soils around Hammam Zriba mine in Northen Tunisia. 69 soil and dike surface samples were collected, field Visible, Near InfraRed (VNIR) and Short-Wave InfraRed (SWIR) reflectance spectra were measured on these surfaces. The X-ray diffraction (XRD) method was used to identify the types of mineral and their associated contents on each collected soil samples. The mineral contents were predicted using the partial least squares regression (PLSR) method using i) field VNIR-SWIR spectra at raw spectral resolution, ii) field VNIR-SWIR spectra aggregated to the SENTINEL-2 spectral resolution and then iii) SENTINEL-2 spectra.This study shows 1) an accurate prediction of four of the seven minerals using field VNIR-SWIR spectroscopy, 2) a slight decrease of performances due to spectral resolution degradation (SENTINEL-2 simulated spectra) and 3) a significant decrease of performances due to spatial resolution degradation, except for fluorite. This work paves the way for large-scale mapping of minerals with high pollution potential using SENTINEL-2 data. In addition, the high frequency of SENTINEL-2 data may be used to monitor the spatial distribution of some minerals with high pollution potential in soils.

Degradation of the macro-drainage water quality of an urban basin in Northeastern Brazil

The growth of cities allied to the lack of investment in urban infrastructure has caused the deterioration of the environment and natural resources. In this context, illegal connections of sewage in rainwater drainage systems has become increasingly frequent, thus compromising the water quality of the same. Campina Grande, located in the state of Paraiba, northeastern Brazil, has been affected by this problem and, therefore, this work aims to evaluate the pollution in its macro-drainage system, within the urban basin of the Prado creek. For that, were analyzed quality indicators of water samples collected at eight points distributed along the Prado creek. In addition, a study was carried out regarding the canal’s self-purification capacity in front of the entire wastewater discharge. Through the laboratory analyzes, it was proven that the drainage water of the Prado canal presents typical concentrations of sanitary sewage with high polluting potential. The points that presented critical quality were: two and four, these being the places with priorities for interventions in the short term. It was noted that, across of the dissolved oxygen profile along the canal, it was verified that the self-purification capacity of the canal was largely exceeded.

Addition of hydrogen peroxide in electrocoagulation of dairy liquids

Standing out on the national and world scene as an important economic and social activity, the dairy products industries are characterized by their high polluting potential, especially due to the liquid effluents generated. In this context, the present work aims to study the application of the electrocoagulation process applied associatively with hydrogen peroxide (H2O2) in the treatment of dairy effluents using iron electrodes. Effluent treatments were carried out with the electrocoagulation process in a continuous flow reactor. For the method using electrocoagulation, the removal efficiencies in relation to color, turbidity, total organic carbon, chemical oxygen demand and nitrogen removal were 97.2%, 97.0%, 77.5%, 63.3% and 92.2%, respectively. The addition of H2O2 to the beginning of electrocoagulation process in the treatment of dairy effluents did not contribute to an increase in the efficiency of removing organic matter. When applied after an electrocoagulation step, it demonstrated to be efficient, reaching COD removals of 97.7%. Therefore, the electrocoagulation demonstrated to be a technically viable alternative for the treatment of dairy effluent.

Oyster shell-based alkalinization and photocatalytic removal of cyanide as low-cost stabilization approaches for enhanced biogas production from cassava starch wastewater

Cassava starch wastewater (CSW) poses a high polluting potential due to its high organic loading and cyanide (CN−) concentration, but this residue can be pretreated and reused. The present work proposes stabilizing the CSW pH and degrading CN- to optimize biogas production. To control the acidity of the CSW we used natural oyster shells as source of CaCO3, and the photocatalytic degradation of CN− was achieved with Degussa P25 TiO2. Natural oyster shells raised pH from 4.5 to 6.2 over 6 h of reaction, efficiently controlling the effluent acidity. After pH stabilization, the TiO2 photocatalyst tested in a degradation process under visible light was able to reduce CN− concentration by 73.02 %. After these pretreatments (pH stabilization and CN- degradation), the CSW was inoculated with sewage sludge (SS) to produce biogas. The pretreatments were proved to be efficient at favoring biogas production as this was heightened by 27.6 %. In addition, the pretreated CSW and digestate (anaerobic digestion) significantly reduced the toxicity of the effluent, assessed by investigating lettuce seeds (L. sativa) germination and root growth. Thus, pretreatments and reuse of residues may potentially provide socio-environmental and economic benefits.

Dimethyl Ether Production from Sugarcane Vinasse: Modeling and Simulation for a Techno-economic Assessment

Industrialization and energy demand increase are highlighted as consequences of world population growth for decades. Thereby, aiming to contribute to sustainable processes capable of mitigating the effects resulting from this process, biofuels have been intensively researched, produced and used in recent years. Among the possibilities, dimethyl ether (DME) stands out with great prospects replacing liquefied petroleum gas and diesel due to its potential as clean fuel. This work aims to conjoin the production of DME, a biofuel with great prospects for technical performance, safety, and economy, with a favorable destination for vinasse, the most worrying residue of ethanol production, due to its high polluting potential and large production volume in several countries. A rigorous and robust simulation of direct synthesis of DME from vinasse-derived syngas is performed using Aspen Hysys and its supplements, evaluating the technical and economic aspects of its production in ethanol distilleries. Results of the proposed scenario point that the process is technically feasible, reaching a purity of 99.9%, respecting the minimum required by standard norms. In addition, the designed process achieved yields of 1 kg of DME for each 1.6 kg of syngas. The simulated process presented a total capital cost of 47.1 millions of dollars, operating costs of 14.1 millions of dollars per year, and utilities cost of 11.2 millions of dollars per year. Considering energy cogeneration, an economy of 9.2% was reached, resulting in a production cost of simulated stage of 98.36 US$/tonne of DME and, considering a complete scenario, an accumulated cost of 233.48 US$/tonne of DME. It demonstrates an economic competitiveness for the DME price and ensures a considerable profit margin for the process. Consequently, the investigated DME production scenario emerges as a promising diesel substitute in a realistic scenario.

A New Technique for Improved Use of Thermal Energy from Waste Effluents

Energy sustainability and environmental protection in general are at the heart of engineering and industry discussions. Countless efforts have been devoted to improving the energy efficiency of industrial processes and specifically to harnessing their waste energy sources. One such source is waste from agro-industrial processes, which is frequently characterized by increased temperatures and high polluting potential. There are multiple available choices for exploiting energy from such waste, but this paper proposes a new alternative technique that substantially improves the efficiency. Based on the technology of leveraging a hot liquid effluent for heating a process fluid, this system introduces a third liquid to be revalorized by drying that is placed in between the hot and cold liquids. By adding stirrers inside the heat exchanger, the thermal resistance of the third fluid is reduced to a negligible level. Thus, this system has almost the same advantages as the previous one, but with the added benefit that it allows drying of a third fluid. One of the specific applications of this proposed technology is using heat from waste effluents to obtain dried food products. In the present work, it was used to dry slaughterhouse blood to obtain so-called “blood meal”, a product with a high added value that is used as pet food or organic fertilizer, and also has many other industrial applications. As shown here, the new technique outperforms existing alternatives in terms of energy efficiency and economic profitability.

Pollution potential and causative hydrogeochemical processes in unconfined aquifer systems in a typical urban setting: emphasis on recharge and discharge areas

The inhabitants of Akure Metropolis, south-western Nigeria, depend solely on groundwater for their domestic, industrial and irrigation purposes. There is a need to delineate recharge and discharge areas for assessment and management of groundwater in these areas. One hundred and ninety (190) dug wells were selected for this assessment. Elevation and water table data aided accurate delineation of recharge, discharge and groundwater divide areas. Thirty-six wells representative of recharge and discharge areas were subjected to pollution assessment [DRASTIC, water quality index (WQI) and runoff potential]. The results revealed that the recharge areas have higher pollution potential and runoff amount than the discharge areas. This implied that groundwater sourced from recharge areas was more pollution prone than that sourced from discharge areas. WQI results revealed that the waters from recharge and discharge areas fall within excellent, good, poor, and unsuitable quality categories. Hydrogeochemical results revealed that concentrations of cations and anions are in order of Ca2+ > Mg2+ > K+ > Na+ and HCO3− > Cl− > SO42− with a predominant Ca–HCO3 facies typifying water from a basement complex environment. Gibbs plot and chloro-alkaline index affirmed the rock dominance and existence of imprints of ion-exchange processes influencing the groundwater quality. Intense weathering activities aided with long resident time spent by the water in the voids of the aquifer media are characteristic in this terrain. Recharge of precipitating water through infiltration into the weathered basement aquifers is a pointer to the greater yield of water in the wells. The possibility that precipitation-weathering process has led to the increase in concentrations of all ionic species and possible pollution of the groundwaters from the recharge and discharge areas cannot be ruled out at all.