Current Environmental Engineering - Current Issue

Meat industry generates various wastes such as effluent, emissions and solid wastes that pose environmental and health problems. The effluent released from the meat industries finds its way into the natural water resources and degrade the water quality. The solid wastes of meat industry create a public nuisance by way of foul smell if it is not handled properly. The effluents, as well as solid wastes of meat industries, are possible sources of pathogens that are hazardous to human health. Waste minimization, segregation of wastes and treatment, processing of wastes to make possible recoveries of by-products and the final disposal are the basic steps for containment of pollution from the meat industry. The effluent treatment technologies include primary treatment, secondary treatment and tertiary treatment. Composting, biomehtanation, rendering, incineration and burial are the processes for disposing of the solid wastes generated by meat industries. Appropriate treatment process is selected considering the level of pollution, mode of disposal and the environmental standards. The treatment and processing of meat industry wastes minimize the pollution problems and also give scope for the recovery of by-products such as bone and meat meal, tallow, methane and manure that have commercial values. The meat industries also generate odours that are required to be contained using suitable control devices. The paper seeks to give an overview of the pollution control technologies currently in use for the treatment of effluents and solid wastes, and possible recovery of by-products.

From the past three to four decades, ecologists and scientists have exhaustively studied the effect of increased artificial light pollution at night on the ecological and physiological behavior of mammals. The Suprachiasmatic Nuclei (SCN) or master clock in the brain of mammals including humans synchronizes the physiological functions with the light: dark cycle. The prolongation of light period in the light: dark cycle disrupts the circadian rhythm of mammals causing several negative or modified physiological consequences. Changed physiological level of melatonin, an important endocrine hormone, had been identified as an important factor causing different consequences such as cancer, diabetes mellitus, metabolic disturbances, oxidative stress, and depression. The presence of artificial light at night is the demand of the era but thoughts must be given to the prevention of consequences due to artificial light pollution and ‘how much is needed’. The review paper discusses the effect of artificial light pollution on the biological clock of humans and associated negative physiological consequences. Further, the paper also briefly discusses the economics of light pollution and measures needed to prevent physiological disorders in humans.

Objective: Selective removal of phenol from organic solvent mixture (benzene + toluene + hexane) or other petroleum by-products have a major concern. Hence, the experiments were conducted on the removal of phenol from synthetically prepared phenolic organic waste by using a green process, ionic liquids. Methods: The ionic liquids, 1-ethyl-3-methyl imidazolium cyanoborohydride, and 1- butyl-3-methyl imidazolium hexafluorophosphate were used for the extraction study. The effect of various operating parameters such as the type of ionic liquids, effluent temperature, extraction time, and the phase volume ratio of ionic liquid and phenol has been studied in details. The ionic liquid, 1-ethyl-3-methyl imidazolium cyanoborohydride selectively extracted 95 % of the phenol from the synthetically prepared organic oil mixture of benzene and toluene, with an initial phenol concentration was 100 ppm. Further, ionic liquids were recycled and reused for six consecutive studies with removal efficiency of about 74%. Additionally, a batch reactor study was conducted to find the process viability for industrial use and 92% phenol removal efficiency was achieved. Results: The study demonstrates the selective removal of phenol from petroleum oil using ionic liquids is a simple and environmentally friendly process for industrial use. Conclusion: This method cannot only extract phenol but also phenol-derived compounds may be extracted from hydrocarbon oil.

Background: The demand of an efficient nanocarrier in drug delivery, graphene and its derivatives are emerging as a rising star due to its remarkable chemical and structural properties. Objective: Graphene oxide (GO) has high surface area and ability to load high amount of aromatic drugs. Hence, the objective of the research was to load Trihexyphenidyl hydrochloride (THP), antiparkinsonian drug on GO ultrasonically by π-π stacking interaction. Methods: GO was synthesized by the modified Hummer method. The conjugation of GOTHP was generated by using Design-Expert Software and release study of GO-THP nanohybrids was performed in the dissolution tester by using a dialysis membrane. Results: By varying an amount of GO and THP, the effect on loading efficiency and drug release was studied. THP showed sustained release behavior with release efficiency of 89% to 98% over 8 h. GO-THP complex was characterized by UV-vis spectrophotometer, FTIR, FESEM and XRD analysis. Conclusion: GO-THP complex showed better-sustained release of the drug and can be useful for the reduction dose frequency as well as adverse effect with better patient compliance.

Background: Atomic Absorption Spectroscopic (AAS) method is most commonly being used due to its reproducibility of results, short analysis time, cost effective, lower level detection and hyphenated in nature. Aims: The concentrations in mg/kg of six heavy metals of environmental implications which includes Cd, Cu, Fe, Mn, Pb and Zn were determined by Atomic Absorption Spectrophotometer PG Instrument Model AA090M046. Methods: Soil and sediments samples were collected at four distinct stations, designated ST1-ST4 which represents areas impacted by human activities on the bank and bed of River Benue, the second largest river in Nigeria. The mean concentrations of Cd and Pb (0.05 mg/kg and 1.26 mg/kg) were of toxicological concern. The decrease in concentrations of the metals across sampling stations followed this sequence Fe > Mn > Pb > Zn > Cu > Cd. The concentration of all heavy metals studied were significantly high in samples from station S4 and S1 compared to S2 and S3. Levels of metals associated with the exchangeable, reducible, oxidisable and residual fractions ranged from 0.083 mg/kg to 199.959 mg/kg; 0.037 mg/kg to 219.118 mg/kg; 0.040 mg/kg to 168.850 mg/kg and 0.037 mg/kg to 116.409 mg/kg respectively. Results: The soil and sediments were slightly alkaline with pH values ranging from 7.98 - 8.53. The mobility factor of cadmium in all the sample stations ranges from 28.06 – 69.27 mg/kg. The high value of Cd and Zn in the exchangeable fraction could indicate high mobility rate and readily availability of these metals for uptake by aquatic organisms. Conclusion: The aim of the study was therefore to assess the impact of metallic contaminants on the sediment, evaluate the pollution status of the sediments by the application of geoaccumulation index and their mobility rate.

Objective: The main focus in the current work is to investigate how diverse heating systems and their locations influence the indoor thermal environment in an exhaust- ventilated room. Methods: Four systems for heating the room were used in the current study, in which, heat was transferred by convection and radiation. The four systems were: wall and floor heating at low temperatures, Medium Temperature Radiator (M.T. radiator) heating and High Temperature Radiator (H.T. radiator). Computational Fluid Dynamics (CFD) simulation was used to investigate indoor temperature, vertical air temperature gradient and thermal comfort for each case. The ventilation rate was set to be 6 air changes per hour (ACH) entering the room through a vent over the window. Results: The findings from the current work were that the low temperature heating systems had better temperature distributions with lower vertical Air Temperature Differences compared to high and medium temperature radiator systems. Conclusion: The Predicted Mean Vote (PMV) and the predicted percentage of dissatisfied (PPD) based on Fanger’s model were calculated for all cases, and were found to be in the recommended ranges.

Background: Effective treatment of wastewaters for potentially toxic metals especially at affordable cost is critical to the well-being of man and the environment. Objective: This study optimized the conditions for the application of Calophyllum inophyllum seed husk as biosorbent for simultaneous removal of heavy metals from aqueous solutions and investigated the removal efficiencies of the biosorbent for Pb2+ and Cd2+ in wastewater samples. Methods: The dependence of the adsorption process on pH, adsorbent dosage, temperature, initial metal ions concentration, and contact time was evaluated in a batch system by determining the degree of adsorption of Pb2+ and Cd2+ in simulated industrial wastewater before application of the biosorbent for metals cleanup in industrial and domestic wastewater samples. Results: The results showed that charring and microwave irradiation of the biosorbent produced the best performance. The pH of the aqueous solution played a crucial role in the performance of the biosorbent. Optimum adsorption for both metals occurred within the first 60 minutes of the process at pH value around 9. Kinetic studies of the process gave good correlation coefficients for a pseudo-second order kinetic model with adsorption data that fitted well into the Freundlich and Langmuir models but with Freundlich isotherm displaying better fitness. The adsorption capacities of the biosorbent were 42.19 and 22.47 mg/g for Pb2+ and Cd2+, respectively. Conclusion: The study concluded that the good adsorption capacities of Calophyllum inophyllum seed husk for the metals is an indications of its considerable potential as a low-cost biosorbent for simultaneous removal of potentially toxic metals from wastewaters.