Removal of Chromium(III) and Other Physical Parameters from Chrome Tan Wastewater and Recovery of Chromium from the Precipitating Sludge

This study was adopted to investigate the removal of Cr(III) and other physicochemical parameters of chrome tan wastewater. For this purpose, three precipitating agents, CaCO3, NaHCO3, and MgO, were used to treat chrome tan wastewater. After treatment, it was found, in three different dose trials, that each agent removed almost 97-99.5 % of chromium. At the same time, it was observed that with the increase of doses, removal percentage of TDS, conductivity, and turbidity of effluent were reduced. In the case of NaHCO3 and CaCO3, Cr(III) removal percentage at optimum pH was found to be 99.97% and 99.95% respectively, whereas the maximum removal percentage for MgO was found to be 99.98%. The NaHCO3 and CaCO3 were found to be comparable to MgO for Cr(III) removal from chrome tan wastewater. The recovered chromium concentration in the sludge for NaHCO3 and CaCO3 were also similar to that of MgO. This research suggests that these two precipitating agents can be used in the same way as MgO, for Cr removal and recovery treatments. Moreover, this recovered chromium can be reused, thus reducing the environmental pollution

Variations of Raw Milk Components and Amino Acid Profiles in Different Dairy Buffalo Crossbreds

This study aimed to assess the relationship between milk components and amino acid (AA) profiles among different buffalo crossbreds in Bangladesh. A total of thirty-six (36) lactating buffaloes were selected from Murrah, Nili-Ravi, and Mehsana crossbreds, and they were assigned to 03 groups, each with 12 buffaloes. The total experimental period was 10 weeks, including the initial 10 days of diet adjustment. The results from the experiment revealed that milk protein, fat, and total solids contents of Murrah crossbred was significantly (p<0.05) higher than Mehsana and Nili-Ravi crossbreds. In contrast, the lactose content of all buffalo crossbreds was statistically similar (p>0.05). In the case of milk amino acid contents, all the milk samples entailed a higher concentration of Glutamic acid (0.9-1.00 g/100 g of milk), whereas Cysteine had the lowest concentration (0.02-0.05 g/100 g). The most prevalent essential amino acids were Leucine, Lysine, and Phenylalanine, whereas the most prevalent non-essential amino acids were Glutamic acid, Proline, Asparagine, and Serine. Lysine, Isoleucine, Leucine, Phenylalanine, Cysteine, and Histidine concentrations differed significantly (p<0.05), and at the same time as the other 11 AAs concentrations were found non-significant (p>0.05). The highest Lysine: Methionine ratio observed in Murrah buffalo was about 3.20%, while in Mehsana and Nili-Ravi buffalo was about 2.80 and 2.50%, respectively. Thus, it was evident from the study that the raw milk components and amino acid composition vary considerably in the different lactating buffalo crossbreds. Finally, the compositional data of raw milk may create the way of sustainable use of milk from dairy buffalo crossbreds and improve food and nutrition security, particularly in developing countries

Evaluation of bloom dynamics and seasonal abundance of cyanobacteria in eutrophic fish culture ponds at three different regions of Bangladesh

Seasonal cycle and bloom dynamics of cyanobacteria in relation to environmental parameters were studied in three areas- Godagari Upazila under Rajshahi district (GD ponds), Bogra city (BG ponds) and Singra upazila under Natore district (SG ponds) from September 2014 to August 2015. Standard methods were followed to analyze the water quality, sediment parameters and cyanobacterial cell density. Except temperature, mean values of all water quality parameters were found significantly different (P < 0.05) among the three study sites. 7 genera of cyanobacteria were identified whereas the highest density was recorded during September in all the studied ponds in order of BG ponds (130.36×106 cells/l) > SG ponds (84.93×106 cells/l) > GD ponds (58.74×106 cells/l). Gradual decrease in cell density was observed from November to January, whereas the lowest density (12.25×106 cells/l) was recorded at BG ponds in December, 2014. Higher values of soil organic matter, total nitrogen and pH were found to play significant role in determining higher cyanobacterial cell density at BG ponds compared to SG and GB ponds. The dominant species recorded in all the three studied regions was Microcystis sp

Current status of bacterial contamination in some fish species of Bakkhali river Estuary, Bangladesh

The present study aims to investigate the isolation of human pathogenic bacteria (Escherichia coli, Salmonella spp. Shigella spp. and Vibrio spp.) and in gills, intestines, skin of fishes of Bakkhali River Estuary, Cox’s Bazar. A total of 50 fish species (25 of Pomadasys hasta and 25 of Glossogobius giuris) were collected from two sampling stations namely Station-1 (Rumalia Chara) and Station-2 (Kusturi Ghat). Bacterial analyses were made by standard methods. Total heterotrophic bacterial load of the isolates was found to be lower than the recommended public health and standard. However, the highest pathogenic bacterial (E. coli, Salmonella spp. Shigella spp. and Vibrio spp.) count at Station-2 might be due to the contamination of municipal and domestic wastes and discharges from small industries that constitute the main pollution source of this estuarine river. Skin was found to be the most preferred organs for higher bacterial load compared to intestine and lower count was recorded in gills. Further research on the microbial quality assessment should be undertaken to prevent pollution of this river estuary

Modeling of Potato Shelf Life on Evaporative Cooling Storage

A model of evaporative cooling storage system was designed to increase potato shelf life for improving potato storage system. Two cultivars of potato ‘Diamant’ (100 gm and 51 gm per tuber) and ‘LalPakri (23 gm and 11 gm per tuber) were placed on four shelves of the bin. Each shelf holds 240 kg of potato from 23 march 2013 to December 2013. Potato spoilage, sprouting, shrinkage, moisture content, vitamin C and total sugar content of potato were measured. Experimental results revealed that potato spoilage progressively increased from April to November and sprouting of potato gradually increased from June to October, but stopped in November. The cumulative spoilage and sprouting were much lower in the improved bin compared to traditional farmer’s practices. Shrinkage of potato was found higher in farmer’s practice than that of storage bin from October to November. Moisture content of potato was higher during May and reduced gradually to the lowest value during November in both of practices. No significant difference was found in two practices on vitamin-C content. Sugar content of ‘Diamant; potato was lower in the storage bin during November. According to data analysis and regression curve storage bin model was more appropriate for both cultivars than farmer practice and significantly more appropriate for ‘LalPakri’ potato

Amelioration of the Detrimental Effects of Water Deficit Stress on Lentil (Lens culinaris Medik) Through the Utilization of Poultry Litter-Based Compost

It is critical that Bangladesh faces water scarcity during the dry season, affecting lentil (Lens culinaris Medik.) yield and some yield components during seedling and flowering stages. Thus, a two-factorial pot experiments (The experiment comprises Factor A: three fertilization levels i.e. F1 = Control [inorganic], F2 = poultry litter-based compost [20 ton/ha], F3 = poultry litter-based compost [30 ton/ha]; Factor B: two irrigation levels such as W1 = 100% field capacity [FC] and W2 = 70% FC) were designed at Hajee Mohammad Danesh Science and Technology University, Dinajpur, from November 2018 to April 2019. And it was investigated how the poultry litter-based composts affected the morpho-physiology, yield and yield components of the lentil (BARI Masur-4) variety under different irrigation stress levels. Obtained results revealed that the tallest plant (30.7 cm at 75 DAS) and maximum branch number per plant (14.1 at 65 DAS), leaf chlorophyll a (0.30 mg/g), highest RLWC (70.28%), lowest proline content (1.57 µ moles g-1 FW), maximum number of pods per plant (39.4 at 75 DAS) and total grain yield (3.62 kg/m2) were recorded from compost F3 (poultry litter-based compost 30 tons/ha) with W1 (100% FC). Results also showed that the yield contributing attributes and yield of lentils were drastically reduced by water stress conditions with different rates of fertilization. In drought conditions (W2 = 70% FC), F3 (30 ton/ha poultry litter-based compost) fertilization produced the highest plant height (30.20 cm at 75 DAS), number of branches (11.5 at 65 DAS), stem dry weight (0.35 g), lowest proline (3.88 µ moles g-1 FW), highest pod number per plant (33.1), weight of 100-seed (2.36 g), total grain weight (2.77 kg/m2), harvest index (58.84%) compared to other fertilizations (F1 and F2). In summary, F3 (30 tons), a compost made from poultry litter, provides better soil conditions under drought conditions compared to F1 and F2 in the year of 2018-19 at the 0 and 20 tons/ha, respectively under the field conditions

Computational Investigation Of Zn-based Single Buffer Layers Toward Cd-free High-efficiency CIGS Thin Film Solar Cells

The photovoltaic performance of copper indium gallium diselenide (CIGS)-based solar cells with Cd-free single buffer layers and a barium disulfide (BaSi2) back-surface field (BSF) has been studied through a numerical approach using a one-dimensional solar cell capacitance simulator (SCAPS-1D). The efficacy of the buffer layer of cadmium sulfide (CdS) via FTO/CdS/CIGS/BaSi2/Mo heterostructure has been studied first and thereafter toxic CdS is replaced by various non-toxic buffers; zinc selenide (ZnSe), indium-doped zinc sulfide (ZnS:In), and indium sulfide (In2S3). Comprehensive research has been performed on the effects of buffer layer thickness, gallium (Ga) concentration in CIGS absorber, BaSi2 BSF doping density, various back contact metals, and cell operating temperature. The highest power conversion efficiency (PCE) of the CIGS-based solar cell with the CdS buffer layer is 26.24 percent, while solar cells with Zn-based buffers made of ZnS:In or ZnSe show improved PCE of 17.68 percent and 17.56 percent, respectively. This study demonstrates the enormous potential of Zn-based ZnS:In and ZnSe buffers for the experimental fabrication of high-efficiency thin-film solar cells with the following structure: FTO/buffer/CIGS/BaSi2/Mo

Flow and Strength Characteristics of Ultra-high Performance Fiber Reinforced Concrete: Influence of Fiber Type and Volume-fraction

Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) has emerged all of the concrete in the construction industry because of its high strength, durability, serviceability and excellent ductility recently. Due to its high production cost, UHPFRC restricts its large-scale structural application. The conventional UHPFRC preparation consists of expensive materials such as specially graded sands which require complex mixing and curing process. The aim of this paper is to determine flow and strength properties of UHPFRC with the variation of fiber type and fiber volume-fraction. The UHPFRC composition was selected with four different fiber volume fractions (Vf = 0%, 1%, 2%, and 3%) of three different steel fibers at varying curing ages of 7, 28, 56 and 90 days within an identical mortar matrix. The paper provides an overview on the workability properties of UHPFRC followed by the presentation of compressive strength test results with different fibers and its volume-fraction with varying curing ages. The higher fiber volume-fraction resulted in a lower flow, and consequently an improvement of compressive strength observed up to 3% volume-fraction of fibers at 56 days curing. Finally, test results are compared and discussed with regard to the main variables: fiber volume-fraction, types of fiber; and curing ages of the specimens