Evaluating the performance of a turbulent wet scrubber for scrubbing particulate matter

A turbulent wet scrubber was designed and developed to scrub particulate matter (PM) at micrometer and submicrometer levels from the effluent gas stream of an industrial coal furnace. Experiments were conducted to estimate the particle removal efficiency of the turbulent scrubber with different gas flow rates and liquid heads above the nozzle. Particles larger than 1 µm were removed very efficiently, at nearly 100%, depending upon the flow rate, the concentration of the dust-laden air stream, and the water level in the reservoir. Particles smaller than 1 µm were also removed to a greater extent at higher gas flow rates and for greater liquid heads. Pressure-drop studies were also carried out to estimate the energy consumed by the scrubber for the entire range of particle sizes distributed in the carrier gas. A maximum pressure drop of 217 mm H₂O was observed for a liquid head of 36 cm and a gas flow rate of 7 m³/min. The number of transfer units (NTU) analysis for the efficiencies achieved by the turbulent scrubber over the range of particles also reveals that the contacting power achieved by the scrubber is better except for smaller particles. The turbulent scrubber is more competent for scrubbing particulate matter, in particular PM_2.5, than other higher energy or conventional scrubbers, and is comparable to other wet scrubbers of its kind for the amount of energy spent.

Implications: The evaluation of the turbulent scrubber is done to add a novel scrubber in the list of wet scrubbers for industrial applications, yet simple in design, easy to operate, with better compactness, and with high efficiencies at lower energy consumption. Hence the turbulent scrubber can be used to combat particulate from industrial gaseous effluents and also has a scope to absorb gaseous pollutants if the gases are soluble in the medium used for particles capture.     

Groundwater quality assessment in the village of Lutfullapur Nawada, Loni, District Ghaziabad, Uttar Pradesh, India

The groundwater quality for drinking, domestic and irrigation in the village Lutfullapur Nawada, Loni, district Ghaziabad, U.P., India, has been assessed. Groundwater samples were collected, processed and analyzed for temperature, pH, conductivity, salinity, total alkalinity, carbonate alkalinity, bicarbonate alkalinity, total hardness, calcium hardness, magnesium hardness, total solids, total dissolved solids, total suspended solids, nitrate-nitrogen, chloride, fluoride, sulfate, phosphate, silica, sodium, potassium, calcium, magnesium, total chromium, cadmium, copper, iron, nickel, lead and zinc. A number of groundwater samples showed levels of electrical conductivity (EC), alkalinity, chloride, calcium, sodium, potassium and iron exceeding their permissible limits. Except iron, the other metals (Cr, Cd, Cu, Ni, Pb, and Zn) were analyzed below the permissible limits. The correlation matrices for 28 variables were performed. EC, salinity, TS and TDS had significant positive correlations among themselves and also with NO (3) (-) , Cl(-), alkalinity, Na(+), K(+), and Ca(2+). Fluoride was not significantly correlated with any of the parameters. NO (3) (-) was significantly positively correlated with Cl(-), alkalinity, Na(+), K(+) and Ca(2+). Chloride also correlated significantly with alkalinity, Na(+), K(+) and Ca(2+). Sodium showed a strong and positive correlation with K(+) and Ca(2+). pH was negatively correlated with most of the physicochemical parameters. This groundwater is classified as a normal sulfate and chloride type. Base-exchange indices classified 73% of the groundwater sources as the Na(+)-SO (4) (2-) type. The meteoric genesis indices demonstrated that 67% of groundwater sources belong to a deep meteoric water percolation type. Hydrochemical groundwater evaluations revealed that most of the groundwaters belong to the Na(+)-K(+)-Cl(-)-SO (4) (2-) type followed by Na(+)-K(+)-HCO (3) (-) type. Salinity, chlorinity and SAR indices indicated that majority of groundwater samples can be considered suitable for irrigation purposes.     

The steel industry, abiotic resource depletion and life cycle assessment: a real or perceived issue?

Time and again, there has been a hue and a cry that the world is running out of natural resources and the most prominent among those is the famous study entitled ‘The Limits to Growth’ by the ‘Club of Rome’. Since then the fear of scarcity of abiotic resources has been challenging human societies around the globe, particularly the research community. In this paper we will examine the case of the steel industry to argue how and why mineral resources depletion is an issue that needs to be addressed through life cycle assessment in more detail. This paper shows that a more comprehensive understanding about the current production trends of iron ore and steel, which also requires several vital metals such as copper, manganese, nickel and so on, can provide useful insights in assessing the potential future threat of shortages due to depletion of abiotic mineral resources.     

Acute and chronic toxic effect of lead (Pb) and zinc (Zn) on biomarker response in post larvae of Penaeus monodon (Fabricus, 1798)

Metal pollution produces damage to marine organisms at the cellular level possibly leading to ecological imbalance. The present investigation focused on the acute and chronic toxicity of lead (Pb) and zinc (Zn) by examining the effects of biomarker enzymes in post-larvae of Penaeus monodon (Tiger prawn). Antioxidant biomarker responses such as lipid peroxidation (LPO) and catalase (CAT) activity for Pb and Zn were determined following chronic exposure. Acute Lethal Concentration ₅₀ (LC₅₀) values observed in the study at 96?h for Pb and Zn at 5.77?±?0.32?mg?L^?1 and 3.02?±?0.82?mg?L^?1, respectively. The estimated No Observed Effect Concentration and Lowest Observed Effect Concentration values for Pb were 0.014 and 0.029?mg?L^?1 and that recorded for Zn was 0.011 and 0.022?mg?L^?1, respectively. Among the two metals studied, toxicity of Zn was found to be greater to P. monodon than Pb. The activities of antioxidant defense enzymes and total protein content differed significantly from control following exposure to both metals. Overall, the biomarker studies demonstrated that alterations in antioxidant enzymes and induction of LPO reflect the consequences of heavy metal exposure in P. monodon.     

Mutagenicity evaluation of industrial sludge from common effluent treatment plant

Sludge from common effluent treatment plant (CETP) receiving effluents from textile industries at Mandia Road, Pali, was analyzed to assess the level of mutagenicity. Mutagenicity assay using Salmonella typhimurium tester strains TA 98 and TA 100 gave positive results, thus suggesting presence of genotoxic contaminants in the samples investigated. Further, mutagenic activity of chemical sludge was found to be lesser than that of biological sludge. This result is very surprising and unexpected as it is indicating that some mutagenic compounds are either being formed or certain promutagenic compounds are being converted into stable mutagenic metabolites during the biological treatment of the wastewater effluents. There have been no previous reports giving similar or contrary results. Most of the previous studies have reported effects of single combined sludge.     

The pricing of water services in developing countries

This paper focuses on improving efficiency in the water and sewerage sectors through long-run marginal cost pricing, adjusted for financial needs, externalities, second best considerations, lifeline tariffs and cross subsidization within an integrated water resource planning (IWRP) framework. Supply efficiency suggests that for a given price structure, an optimal long-run investment plan and a corresponding level of supply quality should be determined which maximizes net social benefits. Supply efficiency also requires efficient operation of the water system, including optimization of losses.     

Enhanced solar-light-driven photocatalytic properties of novel Z-scheme binary BiPO4 nanorods anchored onto NiFe2O4 nanoplates: Efficient removal of toxic organic pollutants

Global environmental problems have been increasing with the growth of the world economy and have become a crucial issue. To replace fossil fuels, sustainable and eco-friendly catalysts are required for the removal of organic pollutants. In this study, nickel ferrite (NiFe₂O₄) was prepared using a simple wet-chemical synthesis, followed by calcination; bismuth phosphate (BiPO₄) was also prepared using a hydrothermal method. Further, NiFe₂O₄/BiPO₄ nanocomposites were prepared using a hydrothermal technique. Numerous characterization studies, such as structural, morphology, surface area, optical, photoluminescence, and photoelectrochemical investigations, were used to analyze NiFe₂O₄/BiPO₄ nanocomposites. The morphology analysis indicated a successful decoration of BiPO₄ nanorods on the surface of NiFe₂O₄ nanoplate. Further, the bandgap of the NiFe₂O₄/BiPO₄ nanocomposites was modified owing to the formation of a heterostructure. The as-prepared NiFe₂O₄/BiPO₄ nanocomposite exhibited promising properties to be used as a novel heterostructure for tetracycline (TC) and Rhodamine B (RhB) removal. The NiFe₂O₄/BiPO₄ nanocomposite degrades TC (98%) and RhB (99%) pollutants upon solar-light irradiation within 100 and 60 min, respectively. Moreover, the trapping experiments confirmed the Z-scheme approach of the prepared nanocomposites. The efficient separation and transfer of photogenerated electron-hole pairs rendered by the heterostructure were confirmed by utilizing electrochemical impedance spectroscopy, photocurrent experiments, and photoluminescence. Mott–Schottky measurements were used determine the positions of the conduction and valence bands of the samples, and the detailed mechanism of photocatalytic degradation of toxic pollutants was projected and discussed.     

The potential of corporate environmental responsibility of Chinese state-owned enterprises in Africa

Drawing upon empirical data collected in China and Africa, this article evaluates Chinese overseas corporate social responsibility strategies and their effectiveness in mitigating environmental impacts in parts of Africa. China’s enhanced role within the global economy has profound environmental implications for the world. In particular, China has rapidly expanded its environmental footprint in Africa, largely because of its burgeoning economic presence through trade and aid projects such as infrastructure and public works. These large-scale projects, commonly managed by state-owned enterprises (SOEs), tend to be in sectors that are environmentally sensitive such as oil and gas exploration and construction of major infrastructure. At the international level, global financial institutions along with growing pressure from civil society organizations are encouraging China to demonstrate a commitment to addressing the environmental impacts of its overseas projects. At the domestic level, growing awareness of such issues has generated an emerging trend of Chinese entities promoting and adopting corporate social responsibility (CSR) initiatives. These moves seek to improve the environmental and social impacts of Chinese overseas investments. However, research has shown that the outcomes of Chinese overseas CSR strategies (particularly in environmental protection) vary widely due to the operating procedures of the Chinese SOEs in combination with specific local political and social structures. In general, environmental protection is weak and so there is a need for the Chinese and African governments to create a legislative and institutional framework to address Chinese investment in Africa especially in the area of natural resource extraction.     

China as a new shaper of international development: the environmental implications

The emergence of China as a global player challenges the pre-existing dominance of the OECD countries and will continue to be a crucial force for global change in coming decades. The implications of China’s rise will be most significant for low- and middle-income countries, but the outcomes will also affect China’s relations with traditional donors and the understanding of the process of development. While these issues are increasingly explored at the political and economic level, very little analysis is available for the environmental impacts that China has on low- and middle-income countries. It is well understood that China plays a major role in relation to climate change, energy use and natural resource use at the global level; however, the perspective of China’s environmental impacts on low- and middle-income countries is underexplored. This Special Issue, therefore, elaborates the rise of China from the environmental perspective and assesses the impacts of China’s rise on low- and middle-income countries for international research, policy and practice in the field of environment and development. The findings draw on insights relevant for energy, water, forestry and land issues in Asia, Africa and Latin America.     

Treatment of simulated Reactive Yellow 22 (azo) dye effluents using Spirogyra species

The potential of commonly available green algae belonging to Spirogyra species was investigated as viable biomaterials for biological treatment of simulated synthetic azo dye (Reactive Yellow 22) effluents. The results obtained from the batch experiments revealed the ability of the algal species in removing the dye colour and was dependent both on the dye concentration and algal biomass. Maximum dye colour removal was observed on the third day for all the system conditions. Monitoring of ORP values helped to understand the overlying biochemical mechanism of algal-dye system. Based upon the results, the dye-algal treatment mechanism was attributed to biosorption (sorption of dye molecules over the surface of algal cells), bioconversion (diffusion of dye molecules into the algal cells and subsequent conversion) and biocoagulation (coagulation of dye molecules present in the aqueous phase onto the biopolymers released as metabolic intermediates during metabolic conversion of dye and subsequent settlement).