The optimal performances of starches produced from two cassava varieties–Manihot aipi (SMA) and Manihot palmate (SMP) as bioflocculants for the treatment of textile wastewater were investigated in this study. The central composite rotatable design was used to investigate the effects of varying dosages of each cassava starch, wastewater-pH, and settling time on the turbidity removal from the wastewater with alum as the primary coagulant. Highly significant second-order multilinear quadratic regression models were developed from the experimental data, resulting in a very high coefficient of determination (r2) values of 0.999 for the SMA and 1.000 for the SMP models. The optimum cassava doses of 50 and 150 mg/L, pH-values of 6.5 and 8.0, and settling times of 95 and 77 minutes led to predictive maximum turbidity removals of 98.35 and 88.87%% with desirability functions of 0.95 and 0.63 for the SMA and SMP, respectively. The corresponding observed turbidity removal recorded at these optimum conditions were 88.72% and 88.52% for the SMA and SMP, respectively. At these optimum conditions, there was no significant difference between the predicted and observed turbidity removed from the wastewater at a p≤0.05 significance level. Verification of the Jar tests showed a good agreement between the experimental data and the models and confirmed that the SMA was superior to the SMP in supporting the alum to remove turbidity from the textile wastewater. As a result, the study revealed that Manihot aipi starch has more flocculating capability than Manihot palmate for the treatment of textile wastewater.

Textile effluents are highly colored for synthetic dyes, cause significant water pollution due to high pH, TDS, EC, BOD, and COD content, and are harmful to aquatic species. Among different treatment processes, biological treatment process is considered as a promising approach. In this investigation, a mixed aerobic bacterial consortium was used for the treatment of wastewater. In addition, the fenton process with a normal sand filter was used for treatment and compared with the biological method. The mean values of BOD, COD, TDS, EC, DO, and pH in the raw wastewater indicated that the effluent was highly contaminated according to Bangladesh standard (ECR, 1997). Both the biological treatment process and fenton process separately showed promising removal of pollution load. The aerobic mixed bacterial consortium reduced TDS (66.67%), EC (60%), BOD (91.67%), and COD (85.45%) and fenton process reduced TDS (74.71%), EC (55.11%), BOD (88.33%), and COD (83.63%) compared to the raw effluent bacterial consortium simultaneously degraded dyes and decolorized the wastewater from dark deep green to transparent. Color removal for the mixed aerobic bacterial process after 72 hours of aeration was 58.57% and for the fenton process with a normal sand filter was 80%. BOD and COD removal percentages for aerobic mixed bacterial consortium showed higher removal efficiency than the fenton process with a normal sand filter. Though 92 hours of aeration showed the maximum satisfactory result, aeration time could be reduced to 72 hours which also satisfied the Bangladeshi standard (ECR, 1997).

Polycyclic Aromatic Hydrocarbon profile of Kpite oil spill impacted site in Rivers state, Nigeria was evaluated to determine the level of contamination of the soil. Four composite oil impacted soil samples were collected at different depths; surface (0-15cm) and subsurface (15-30cm) after a field reconnaissance. Extraction of the oil was carried out on the soil samples and the Polycyclic Aromatic Hydrocarbons were quantified using the Gas Chromatography- flame ionization detector. Results showed that Naphthalene was the most abundant in the range of 0.25 to 1.49 mg kg-1. Fluoranthene followed closely with concentrations in the range of 0.01 to 1.28 mg kg-1. PAHs like Benzo (k) fluoranthene, Benzo (e) pyrene, Dibenzo (a, h)anthracene, Indeno (1, 2, 3-cd) pyrene and Benzo (g, h, i) showed low concentrations of less than 0.01 indicating that strong weathering had occurred. The diagnostic ratios such as Phenanthrene/Anthracene (Phen/Anth), Benzo (a) anthracene Chrysene ((BaA)/Chry) and Fluoranthene/Pyrene (Flth/Py) and sum of chrysene/Phenanthrene ΣChry/ΣPhen were calculated and used to unravel the source of hydrocarbons. Results showed ratios of Flth/Py >1.0 and Phen/Anth ranges from 1.19 to 2.03 (< 10) which denote contamination sources, implying that the hydrocarbon sources are not just petrogenic but rather may due to contamination sources of combustion processes or the area was exposed to bush burning.

The heavy metal pollution in soil caused by mining area development is a global problem. In order to screen the ecological restoration plants of copper silver tailings in arid and high saline alkali areas, and evaluate their economic value, nine kinds of plants naturally growing in the northwest copper silver tailings pond were selected, the enrichment and transfer characteristics of eight heavy metals by this plants was analyzed, and potential health risks for humans of plants were focused. The results showed that the heavy metals such as Cd, As, Cu, Hg and Ag are all from the open-air accumulation of tailings slag. Translocation factors of Cu, Ni and Cr by C. tragacanthoides are 2.1205, 53.1548 and 13.7622, bioconcentration factor of Cu, Ni and Cr by C. tragacanthoides are 1.8888, 7.1979, 7.4653, C. tragacanthoides is the hyperaccumulator for Cu, Ni and Cr. Hazard index in roots of S. collina, C. virgata and A. splendens to adults is more than 1, it has a potential non-cancer effects for more than half of adults, and for over 86.23% of children. Ag, Cr and As contribute the best to HI, and the cumulative contribution rate of the three elements can reach 85.59% to 96.39%. It is necessary to improve the treatment of tail slag to reduce environmental pollution, C. tragacanthoides can be considered as heavy metal remediation plants in arid and high saline copper tailing areas, but there is no medicinal value for these plants as ecological reconstruction in tailings area.

Increase in advanced electronic technology leads to environmental issues related with its disposal. Electronic waste i.e., video card and random access memory were used for studying extraction of precious metals using Paenibacillus sp. Metal contaminated soil was used for the isolation of exopolysaccharide producing strains. The isolate was identified as Paenibacillus sp. based on morphological, biochemical tests and 16S rRNA sequencing. Metal content analysis of soil and e-waste was carried out using X-ray Fluorescence spectroscopy. The vanadium element was more in the soil sample which was 0.487 mg/g and in electronic waste sample copper content was more which was 250 mg/g. Paenibacillus sp. produced capsule which was observed under bright, dark field and phase contrast microscope. Scanning electron microscopy was done for the study of morphological changes of exopolysaccharide producing Paenibacillus sp. in chitin broth and on chitin agar medium with and without e-waste. The Fourier Transform Infrared Spectroscopy analysis of exopolysaccharide produced by Paenibacillus sp. grown on chitin agar and chitin agar with e-waste showed presence of different functional groups. The one step and two step bioleaching experiments were carried out for testing efficacy of biomass on metal leaching. Paenibacillus sp. showed its potential for the extraction of precious metals viz., gold, silver and copper from electronic waste. Paenibacillus sp. recovered gold (0.001%), cadmium (45%), copper (50%), iron (46%), manganese (88%), palladium (56.9%) and zinc (87.12%) by two step fermentation. The study is useful for the bioleaching of precious metals from electronic waste.

This paper explores long-run and causal effects of financial development, real growth, urbanization, gross capital formation and energy consumption on CO2 emissions in Thailand by utilizing recent econometric techniques. The study employs ARDL technique to examine the long and short run interconnection between CO2 emissions and the regressors. Furthermore, we employ the FMOLS, DOLS and CCR as a robustness check to the ARDL long-run estimator. The study use time-series data spanning from 1971 to 2016. The study also utilizes the wavelet coherence technique to collect information on the association and causal interrelationship among these economic variables at different frequencies and timeframes in Thailand. The study objectives are structured to answer the following questions: (a) does the selected macroeconomic indicators impact CO2 emissions in Thailand? (b) if so, why? Findings reveal; (i) Negative and insignificant link between CO2 emissions and urbanization. (ii) GDP growth affects CO2 emissions positively. (iii) The interconnection between CO2 emissions and energy usage is positive. (iv) Gross capital formation impact CO2 emissions positively. (v) Positive interconnection exists between financial development and CO2 emissions in Thailand. Additionally, the wavelet coherence result provides a supportive evidence for the ARDL long run result. Based on these findings, policy directions were suggested.

Tree rings have been used to reconstruct past climates as well as to assess the effects of recent climatic and environmental changes on tree growth. Industrial emission is one of the major sources of pollutants in the atmosphere. This study determined heavy metals pollution chronologies from industrial emissions in the atmosphere of the Tema industrial area of Ghana using tree-rings as bio-indicators. Swietenia mahagoni (Mahogany) tree was bored and the rings counted and age determined to be 50 years spanning from 1968 to 2018. Tree growth rates were calculated through ring width measurements and related to annual precipitation data spanning over the sampling period. It was observed that wet seasons correlate with high growth rates of trees while low precipitation seasons correspond to low or no growth rate of trees. Energy Dispersive X-ray fluorescence (EDXRF) was used to investigate the presence and concentration of the four heavy metals (Cu, Zn, Fe and Pb). Concentration of Cu, Zn, Fe and Pb ranged from (1.92—6.70 mg/kg), (5.37 – 13.9 mg/kg), (0.10 – 0.36 mg/kg) and (12.13—90.13 mg/kg), respectively. Surprisingly, an increasing trend in concentration was observed for Zn and Cu with levels higher than the WHO guideline for heavy metals in the plant.

This study assesses heavy metal levels in water, soil, and vegetables (swiss chard, lettuce, cabbage, collard green, tomato, green pepper and carrot) irrigated with waste water in Gamo, Ethiopia. The samples of soils, water, and vegetables were randomly collected, processed, and analyzed for heavy metals using atomic absorption spectrophotometry. The results obtained show that the irrigational water is profoundly contaminated with heavy metals Cd, Cr and Ni and Pb, Zn and Cu had the lowest concentration in irrigation water. The levels of Cd in Kulfo river area and Chamo Lake area and Ni in most of the farm soils were also found to be higher than the guideline values. The study also revealed that the mean levels of Cd in most vegetables and Cr and Pb in some vegetables were higher than the maximum recommended limits set by WHO/FAO. In general the results show that the highest concentration of the heavy metals was obtained from Kulfo river area compared to the Arbaminch textile share company area, Abaya Lake area, and Chamo Lake area. Cabbage was maximally contaminated with potential toxic elements followed by Swiss-chard, carrot, tomato, collard green, green pepper and lettuce. Hence, from kulfo river area frequent consumption of cabbage and Swiss chard may cause serious health risks to consumers. The levels of many elements were found to vary with location, suggesting localized inputs of the various contaminants related to industrial and other activities that generate wastewater. This study recommends regular monitoring of heavy metals in soils, waters, and foodstuffs to prevent excessive accrual in food chain.

The emission and dispersion of pollutants from the tanks of coking and tar refining industries in the environment is always probable. This study aimed to evaluate the hazard radius of benzene release from the tank of one of the coking and tar refining industries. Areal Location of Hazardouse Atmosphere (ALOHA) model Version 5.4.7 was used to predict the hazard radius of leakage and dispersion of benzene from a tank in different seasons. The maps of the toxic and flammable vapor cloud of benzene, evaporation rate from puddle and the concentration of toxic and flammable vapor cloud inside and outside of the office building were prepared. The results indicated that the maximum average benzene released from the tank was 282 Kg/min and the total amount of benzene leakage was 11997 kg in 60 min in summer. The maximum diameter of the created evaporating puddle was 71 m in autumn. The maximum toxic and flammable concentrations of benzene inside an office building were 772 and 936 ppm, respectively whilethey were 3720 and 3540 ppm outside a building in autumn. Based on the Acute Exposure Guideline Levels (AEGL) and Lower Explosive Limit (LEL) criterias, the maximum hazard radius was 1200 and 200 m in autumn. The toxic vapor cloud of benzene covered some parts of the adjacent coking plant. However, the boundaries of the flammable vapor cloud failed to reach the adjacent industries. The scenario of this study is safe for the adjacent residents and unsafe for the personnel. Thus, presenting a strategy to deal with this process incident is essential.

The present study deals with groundwater pollution in multilayer aquifer. The model is based on decomposition of finite layers in semi-infinite groundwater reservoir. A constant pollutant source is injected at the input boundary of the uppermost layer (UML) of the landfill. At the intermediate inlet boundary, some average value for the longitudinal exchange of the input source concentration in each sub-layer is considered from the previous layer. Initially, the aquifer is not solute free in each sub layer that means some constant background contaminant concentration exists. In each sub layer, concentration gradient is assumed to be zero at the extreme boundary. The linear sorption and first orders decay terms are considered to model the groundwater pollution in multilayer aquifer. The Laplace transform technique is adopted to solve one-dimensional (1D) advection-dispersion equation (ADE). This approach is helpful to understand the solute migration in finite sub layers. The results are elucidated for the different time periods to examine the peak of pollutant concentration level in geological formations.