Showing papers in "Environmental Technology and Innovation in 2018"

Water purification by using Adsorbents: A Review

Abstract: There are number of water purification techniques but the adsorption is one of the most simplest, effective and economical method for wastewater purification. In this article a large number of solid adsorbents such as Natural adsorbents, Agricultural Wastes, Industrial wastes, Biomass, Nanoadsorbents: Carbon based nanomaterials, Nobel metal based nanomaterials, Metal oxide based nanomaterials, Spinel ferrite based nanomaterials, Nanocomposites, Dendritic polymers; Geopolymer cement have been discussed for the removal of different pollutants from waste water. Removal of Fluoride, Phosphate, Nitrate and Radionuclides from wastewater has also been reviewed in this article. Adsorption isotherm models, kinetic models, thermodynamic parameters and adsorption mechanism have also been discussed. The present article lists different type of adsorbents and reviews state-of-the-art of the removal of different pollutants from water. The efforts have been made to discuss the sources of contamination and toxicities of pollutants. Adsorption mechanisms responsible for pollutants removal by different adsorbents have been reviewed. Attempts have also been made to point out the advantages and drawbacks of adsorbents and the future research needs in the area of water purification by adsorbents.

Palm oil industry in South East Asia and the effluent treatment technology—A review

Abstract: The progress of Palm Oil Mill Effluent (POME) treatment in meeting with the regulation and standard stipulated by the Environmental Authority always been a major issue in Palm oil industries. To occupy the palm oil world market demand, palm oil industry needs to produce more than the market demand to supply necessity. Currently, South East Asia country such as Malaysia, Indonesia and Thailand rank the top country with the largest production of palm oil in the world. However, the increasing demand for the palm oil has resulted in even massive waste especially palm oil mill effluent (POME). Direct discharge of POME will adversely affect the environment. In 2011, 53 million tonnes metric of palm oil produced and 89% of this production comes from Malaysia and Indonesia. Thailand, however, used the palm oil solely for domestic usage. Since POME has been declared among the major source of pollution, a great deal of research and development including application devoted to enhance the current treatment method for POME to consistently meet the proposed stringent regulatory requirement by environmental authority. Conventional treatment such as ponding system is the most commonplace method to treat POME through the application of ponding system which is include aerobic and anaerobic treatment. Recently, the alternative methods such as coagulation, flocculation, adsorption, advanced oxidation process (AOP) and membrane technology to treat POME has shown a promising result compared to the conventional method.

Petroleum hydrocarbons (PH) in groundwater aquifers: An overview of environmental fate, toxicity, microbial degradation and risk-based remediation approaches

Abstract: Petroleum hydrocarbon (PH) contamination of soil and aquatic ecosystems is a serious global issue. PH are classified as xenobiotics and emerging priority pollutants. When released into the environment, fate and behavior of PH varies widely with the particular composition and physicochemical properties. Usually, PH with higher molecular weight are toxic and seldom mobilizes in subsurface plumes when compared to their low molecular weight counterparts. Due to the toxic, mutagenic and carcinogenic nature of PH, various remediation approaches are currently employed for their clean-up from the environment. Degradation of PH by the activity of native microbes is considered as a significant eco-friendly and cost effective approach for the remediation of PH contaminated sites. Changes in the microbial adaptations and dynamics are important indicators for monitoring the effects of PH contamination. Several analytical techniques are available for the identification and quantification of PH present in contaminated sites. Also, toxicity tests are widely employed to monitor the effect of remediated sites where analytical techniques fall short to identify certain PH due to the lack of standardized methods and low concentrations. Consequently, this review provides an overview of environmental fate, toxicity, and remediation of PH with particular emphasis on risk-based remediation which considers the use of both analytical and toxicological studies for effective management and remediation of PH contaminated sites.

Comparison of characterization and adsorption of biochars produced from hydrothermal carbonization and pyrolysis

Abstract: Two types of rice-husk biochars, hydrothermally produced hydrochar and slow-pyrolysis pyrochar, were produced at different temperatures and were characterized and used as adsorbent material for the removal of methylene blue, iodine, and copper ions from aqueous solution. The characterization results showed that the hydrochars contained higher heating value, volatile matter content, carbon content and oxygen functional groups, and retained lower oxygen content and ash content than the pyrochars. Although the hydrochar retained relatively lower surface area, its adsorption capacity for methylene blue, iodine, and copper ions was much higher than pyrochar due to its ion-exchange and complexation. The adsorption isotherms of copper ions by two types of biochars were well described by the Langmuir and Freundlich models.

Predicting the Tigris River water quality within Baghdad, Iraq by using water quality index and regression analysis

Abstract: The monthly water quality data sets from ten stations on the Tigris River within Baghdad for the year 2016 were studied. The water quality index (WQI) was calculated using 11 important parameters according to the assigned weight, and its values were used as the dependent variable in stepwise multiple linear regression (MLR) analysis to develop a water quality model (WQM) for the river. Twenty-three physicochemical water quality variables (2760 values) were included in developing the WQM , they are: Aluminum (Al + 3 ), Fluoride (F−1), Nitrite (NO 2 − 1 ), Nitrate (NO 3 − 1 ), Ammonia (NH3), Temperature (T), Total Alkalinity (TA.), Turbidity (Tur.), Total Hardness (TH), Calcium (Ca + 2 ), Chloride (Cl−1), Magnesium (Mg + 2 ), Potential of Hydrogen (pH), Electrical Conductivity (EC), Sulfate (SO4 − 2 ), Total Dissolved Solids (TDS), Iron (Fe + 2 ), Silica (SiO2), Phosphate (PO 4 − 3 ), Dissolved Oxygen (DO), Biological Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), and Sodium (Na + 1 ). The annual WQI mean value during the study was 266; more than the safe value of 100; consequently, the water quality was considered as unsuitable for drinking. Significant differences in WQI values were detected over the months and across stations with the highest WQI values (poor quality) in winter and spring, while the lowest values (better quality) were in summer and autumn. The WQM, which was developed based on the stepwise MLR analysis, consisted of five parameters: Tur, EC, COD, TH, and pH with significant value (r 0.987, R2 0.974, p WQI = ( − 1 . 597 ) ( T u r ) 0 . 478 (EC) 0 . 409 (COD) 0 . 089 (TH) 0 . 291 (pH) 0 . 095 The study results show that the use of WQI as the dependent variable input improved the prediction of MLR model as a tool to understand, simplify and model the water quality variation. The model developed here can help in rapid low-cost water quality evaluation for best management of the Tigris River.

Challenges and future prospects of agri-nanotechnology for sustainable agriculture in India

Abstract: Nanotechnology presenting an inventive frontier in present day agricultural practices is expected to turn into a key force in future by contributing innovative applications. This new approach using nano-principles in agriculture has immense possibilities in handling the world wide challenges of environmental security and sustainability, food production, food safety, food security and global threats of climate change. Nanotechnology is very expansively used in contemporary fields of agriculture, food processing, and food protection, packing industry, dairy industry, packaging, transportation and quality control of agricultural products. It has enormous prospective in making agriculture more proficient and resourceful by using nanoparticles to improve the precision in delivering the nutrients to the specific part at a specific time. Use of nano- based agro-chemicals, ceramic devices, filters; lamination methods have great potential of making agriculture more organized and efficient by transforming the conventional agro-practices. Indian government is also supporting this by making plans to extend support for expansion and commercial applications and acceptance of nanotechnology by encouraging private sector investments and empowering partnerships in public and private sectors . Though nanostructures have enormous benefits in agri-sector, still their relevance and significance had not moved up- to practical field environment. The concerns related to the availability, synthesis, level of toxicity, health hazards, transportation challenges and incongruity of regulatory structure restrict the broad recognition and acceptance of adopting nanotechnology in agriculture. The present paper is an attempt to analyze and propose inputs in addressing the present and future possibilities, perspectives, applications and challenges of incorporating nanotechnology in agricultural sector with a focus on Indian perspective.

Adsorptive decontamination of rhodamine-B from water using banana peel powder: A biosorbent

Abstract: Dyes are potential environmental contaminants, liberated in the aqueous streams by the wastewaters of different industries like textiles, pulp, leather, cosmetics, food and paper industries. The present study is focused on the use of waste banana peel as biosorbent for the inexpensive and efficient removal of dye from aqueous streams. Rhodamine-B is a cationic dye which is basic in nature and soluble in water. It is toxic and can cause harmful effects such as skin irritation allergic dermatitis and cancer. Batch adsorption experiments were performed and parameters such as contact time, biosorbent dose, pH and temperature were varied. The samples under investigation were analyzed by UV spectrophotometer. The obtained data at equilibrium were examined for the modeling of Langmuir and Freundlich isotherms. The value of R2 (correlation coefficient) indicates that the data were better fitted to Langmuir adsorption model. The contact time of 60 min was selected for the adsorption of rhodamine-B on banana peel powder. The influence of biosorbent dose on sorption of rhodamine-B was observed in range 0.04–0.5 g for 60 min with 30 mL of dye solution. The maximum removal for rhodamine-B on the biosorbent surface was observed to be 81.07%. The present work produces easily acquirable, eco-friendly and cheap biosorbent capable of efficient removal of dyes from aqueous media.

Removal of heavy metals (Cu, Pb) from aqueous solutions using pine (Pinus halepensis) sawdust: Equilibrium, kinetic, and thermodynamic studies

Abstract: Natural Pinus halepensis sawdust has been explored as an alternative biosorbent of heavy metals from aqueous solutions. The effects of pH, adsorbent dose, contact time, metal concentration, and temperature on copper and lead sorption efficiency were investigated through batch experiments. The optimum pH range was 5–8 for Pb and 7 for Cu. Optimum adsorbent dose, achieving almost complete Cu and Pb removal was 10 g/L. Contact times at which maximum metal adsorption was achieved ranged between 5 min to 24 h. An increase in initial metal concentration had varying impacts yet always resulted in increased adsorption capacity. Equilibrium adsorption data were best fitted with Freundlich isotherm for Cu while Pb experimental data fitted equally both Freundlich and Generalized isotherm models. Metal adsorption kinetics was very well described by the pseudo second-order model. Higher metal removal efficiencies and improved equilibrium adsorption capacity were observed at higher temperature. The adsorption process was not spontaneous for Cu, and for Pb at lower temperatures. Adsorption was an endothermic chemical process and the positive values of Δ S suggest an increase in randomness at the solid/liquid interface during adsorption.

Adsorptive removal of methylene blue, tetracycline and Cr(VI) from water using sulfonated tea waste

Abstract: Biomass-derived adsorbents are constantly explored for wastewater treatment due to significant advantages such as easy scale-up, cost-effectiveness and environmental-friendliness. Here we report the exceptionally high adsorption capability of sulfonated spent tea leaves towards environmental pollutants such as methylene blue, tetracycline and Cr(VI) is reported through this article. The carbonized form of organic biomass derived from sulfonated tea waste (STW) exhibited unusually high adsorption capacities for methylene blue (1007 mg/g), tetracycline (381 mg/g) and Cr(VI) (438 mg/g) at room temperature. The effect of dosage, time, pH and temperature on the adsorption was systematically investigated. The Cr-adsorbed STW samples were characterized using X-ray photoelectron spectroscopy, electron spin resonance spectroscopy, and Small-angle X-ray scattering (SAXS). Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) and UV–Vis spectroscopy were used to analyze the water samples. A continuous-flow water filter was also developed based on the tea-waste adsorbent to demonstrate its ability to purify waste-water. Such high adsorption of pollutants using a cheaper adsorbent like STW makes it a viable material for commercial-scale water purification.

Biosurfactant and exopolysaccharide-assisted rhizobacterial technique for the remediation of heavy metal contaminated soil: An advancement in metal phytoremediation technology

Abstract: Biosurfactant and exopolysaccharide producing plant growth promoting rhizobacteria can be a best tool for increasing the efficiency of plant assisted remediation of heavy metal contaminated soil; because they can thrive in the stressful environment in a luxuriant way, support plant growth and also contribute to the remediation process. Heavy metals are a noteworthy environmental pollutant and are regarded as biosphere hazard. Numerous chemically based techniques are used to enhance the efficacy of phytoremediation; however, most of them are ecotoxic, highly expensive and lead to incomplete removal of pollutants. To mitigate these technical inherent and to ensure complete removal of toxic heavy metals from soil, an advanced biological tool is the use of biosurfactant and exopolysaccharide-producing rhizobacteria. This can be a promising technique, that has been operative in nature and is cost effective, eco-friendly, efficient and having socio-economic importance over other conventional remediation techniques as well as sustainable for the environment. The present article critically reviews the potential role of root-associated metal resistant, exopolysaccharide and biosurfactant producing rhizospheric bacteria to remediate heavy metal contaminated soil and highlight some insight mechanisms for exploitation of plants and associated rhizobacterial interactions for enhancing heavy metal remediation.

An Overview on Fuel Properties and Prospects of Jatropha Biodiesel as Fuel for Engines

Abstract: The demand for energy is ever increasing since the establishment of human society. In recent years, the demand for energy is steadily increasing due to growth of population and industrial development. As conventional sources of energy are on the verge of extinction and are considered threat to the environment, search for alternative forms of energy is increasing. Biodiesel is one of the sources that can play a pivotal role for future energy, especially in transportation sector, as an alternative to diesel fuel. Jatropha is regarded as one of the best options for biodiesel production in tropical and subtropical developing countries. In terms of fuel properties and emission factors, biodiesel from Jatropha has advantages over conventional diesel. In addition, Jatropha biodiesel when compared with other biodiesel is more environment friendly as there is less emissions of greenhouse gases. A review on performance of Jatropha as a fuel shows that, although emission of NO x is increased from 5.58 to 25.97%, PM is reduced by 50 to 72.73%, CO by 50 to 73%, HC by 45 to 67% and CO 2 by 50 to 80%. However, the future of the Jatropha biodiesel will also depend upon the establishment of low-cost and competent biodiesel production technologies.

Phenols from olive mill wastewater and other natural antioxidants as UV filters in sunscreens

Abstract: Antioxidants are frequently used in sunscreen formulations to complement UV filter photo-protection of synthetic compounds. The current study investigates the application of phenols (recovered from olive mill wastewater) as UV filter in comparison to other natural antioxidants (ascorbic acid and α -tocopherol). The spectrums (220–400 nm) of all assayed antioxidants alone or in combination with synthetic sunscreen agents (Benzophenone-3, Uvinol A, Tinosorb M, TiO2, Octocrylene, OMC and OC-PABA) were obtained and the respective in vitro SPF of the solutions was calculated. Olive phenols were more active UV filters in a broader region of UVB and UVA compared to ascorbic acid and α -tocopherol. However, they were not so active against synthetic compounds especially in the UVB region. The fact that olive phenols absorb in both UV regions of interest allow their application as UV-protection booster in particular cases, e.g. to enhance the absorption of Tinosorb M and Uvinul A solutions in the UVB region and to increase the absorption of Octocrylene, OD-PABA and OMC in the UVA region.

A review of the application of agricultural wastes as precursor materials for the adsorption of per- and polyfluoroalkyl substances: A focus on current approaches and methodologies

Abstract: There is an abundant body of literature surrounding the use of agricultural wastes for the adsorption of pollutants from aqueous solutions. This area of research is often considered as an alternative to conventional treatment techniques. In the past, the research focus centred on the adsorption of toxic metals. Presently, there is an increase in the calls, for researchers to explore new adsorbent materials for the removal of organic pollutants. Since once ingested, these organic pollutants have health impacts such as chronic kidney and liver diseases and endocrine disruption. Hence, there is an increasing need to discover new and efficient ways of removing organic pollutants from water systems. It is worth mentioning that most agricultural wastes are not usually utilized in their original state, but rather modified in diverse ways to increase the material’s surface area of adsorption and porosity. Thermal treatment, carbonization, chemical and physical activation, nanostructuring, grafting with copolymers and many others are some of the widely used methodologies; that are currently being employed for modifying agricultural waste materials for use as adsorbents. In this review, therefore, a discourse on a range of agricultural wastes that have been used as adsorbents for the removal of per- and polyfluoroalkyl substances (PFAS) from aqueous media is provided. A proposition of the use of maize tassel–silver nanoparticles as new comers is made. This review article serves to give key insights on the technical realizations in the area of adsorption of PFAS by utilizing agricultural wastes as precursor materials for preparing adsorbents.

Adsorption of Cu(II) by low cost adsorbents and the cost analysis

Abstract: The present research is investigated on the adsorption potential of sugarcane bagasse (SG), acid modified sugarcane bagasse (ASG), base modified sugarcane bagasse (BSG) and activated carbon (AC) as adsorbents for the removal of Cu(II) from synthetic effluent and industrial wastewater in a batch mode process. The surface morphology and surface functionality of the adsorbents were identified by using scanning electron microscope (SEM) and Fourier transforms infrared spectroscopy (FTIR), respectively. The influences of the effective parameters including initial Cu(II) ion concentration, pH and adsorbent mass were optimized by UV–Vis spectroscopy. The Cu(II) removal efficiency from synthetic effluent using AC, SG, ASG and BSG was observed as 98.5%, 88.9%, 96.9% and 94.8%, respectively at equilibrium for adsorbent dose 5 g/L, initial Cu(II) concentration 10 mg/L and pH 5. The Cu(II) removal efficiency using the industrial wastewater was obtained as 83.45%, 62.53%, 81.40% and 71.77% for AC, SG, ASG and BSG, respectively at adsorbent dose 5 g/L, initial Cu(II) concentration 52.4 mg/L and pH 1.25–1.31. It was determined that the Cu(II) removal efficiency of ASG from synthetic effluent as well as industrial wastewater is comparable with that of AC. The cost analysis has shown that AC is very costly as compared to the other adsorbents used for the studies.

Control of microbial growth in bakery products fortified with polyphenols recovered from olive mill wastewater.

Abstract: Polyphenols recovered from olive mill wastewater and other natural antioxidants [ascorbic acid, tocopherols mixture ( α -, β -, γ - and δ -) and α -tocopherol] were mixed in different concentrations with bread and rusks, stored over a period of 20 days and 12 weeks, respectively, and assayed periodically to different microbiological assays (i.e. Total coliforms, Yeasts-Moulds and Bacillus spp.). Antioxidants were able to induce antimicrobial properties in bakery products and subsequently prolong their shelf life. The optimal concentration of olive polyphenols was this of 200 mg /Kg flour, whereas their emulsification enhanced antimicrobial effect. The formulation of 500 mg α -tocopherol /Kg was also able to extend the shelf life of the bread up to 15 days. Ascorbic acid and tocopherols mixture had did not affect importantly to the overall bread preservation in both assayed concentrations (500 and 1000 mg/Kg). Concerning rusk preservation, α -tocopherol, tocopherols mixture and ascorbic acid were effective at 600 mg/Kg. The results of the study reveal the possibility of polyphenols derived from olive mill wastewater and other natural antioxidants (e.g. α -tocopherol, tocopherols mixture and ascorbic acid) as an antimicrobial agent in foods that undergo oxidative deterioration during cooking (i.e. bakery products).

Novel recyclable (Xanthan gum/montmorillonite) bionanocomposite for the removal of Pb (II) from synthetic and industrial wastewater

Abstract: In the present study, a novel biodegradable Xanthan gum/montmorillonite (XG/MMT) bionanocomposite has been successfully synthesized and was explored for the removal of Pb (II) from synthetic and industrial wastewater. SEM, TEM and FTIR techniques were employed for the characterization of (XG/MMT) bionanocomposite. The effects of several parameters such as pH, contact time and initial metal ion concentration were analyzed. The experimental data was investigated using equilibrium isotherm and kinetic models. The result showed that the pseudo-second order and Freundlich were the best fitted models for the adsorption process. Thermodynamic study illustrates that the adsorption was endothermic and spontaneous in nature. Finally, the worthy regenerative efficacy (up to five cycles) using 0.05M HCl of bionanocomposite proved as economically promising adsorbent for practical applications. Therefore, the findings suggests that the present (XG/MMT) bionanocomposite can be utilized as a potential and novel adsorbent for the removal of toxic heavy metal from wastewater.

Polyphenols recovered from olive mill wastewater as natural preservatives in extra virgin olive oils and refined olive kernel oils

Abstract: This study tests the efficacy of polyphenols (recovered from olive mill wastewater) against ascorbic acid, tocopherols mixture and α -tocopherol for the prevention in oil oxidation. All antioxidants were mixed or emulsified at different concentrations (500–3000 mg/L) with an extra virgin and a refined kernel olive oil, prior heated in the oven at 100 °C (30 min) and 160 °C (120 min). The activity of antioxidants was monitored using the DPPH* radical scavenging assay and the oxidation of treated oils was monitored by determining peroxide value, p-anisidine values, total polar components, “totox” index and extinction coefficient ( K 270 ). Olive polyphenols at 500 and 3000 mg/L reduced the oxidation of both heated oils. Ascorbic acid at 2000 and 3000 mg/L was more efficient than the olive polyphenols, especially in the case of olive kernel oil. Tocopherols formulation showed low effectiveness against most oxidation indexes, probably due to their instability at high cooking temperatures. The outcomes of the current study contribute to the further valorization of olive mill wastewater as a source to produce high added-value polyphenols. The latest could be used as preservatives in olive and vegetable oils as well as in other foods rich in fats, e.g. meat products.

Bentonite coated with magnetite Fe3O4 nanoparticles as a novel adsorbent for copper (II) ions removal from water/wastewater

Abstract: In the present work, the natural bentonite (NB) coated with synthesized Fe3O4 magnetite nanoparticles (CB) was firstly used as an adsorbent to sequester Cu(II) ions from the polluted solutions. The characterization study demonstrated a substantial improvement in several adsorptive parameters of NB after coating, like surface area, surface morphology and topography. From the analysis of the pore diameters, it was observed that the CB lies in the mesoporous materials category with diameters in the range of 2–50 nm. The removal efficiency was optimized as a function of the parameters: pH (3–6), CB dose (0.2–1 g/100 mL solution), and initial Cu(II) concentration (up to 200 mg/L). The results of the isotherm study revealed that the experimental data were fitted well onto the Langmuir model with the maximum amount of Cu(II) (46.948 mg/g) being adsorbed at pH 6, when the CB dose was 0.5 g and it shaking was done at 200 rpm speed, in a reaction time of 120 min. The kinetics of Cu(II) adsorption was chemosorption in nature as confirmed by the fitting with pseudo-second-order model. In addition, the results showed that the intraparticle diffusion was not the dominating mechanism. Comparison of the results of this study and those obtained from literature, it suggests that the CB exhibits an excellent sorption capacity for the Cu(II) removal and, therefore, can be used as a potential material in the adsorption systems for Cu(II) removal from rich wastewater.

Cultivation of Nannochloropsis oculata and Isochrysis galbana microalgae in produced water for bioremediation and biomass production

Abstract: This work investigates the viability of growing two microalgae species Nannochloropsis oculata and Isochrysis galbana in culture medium containing oilfield produced water (PW) for simultaneous wastewater treatment and biomass production. Several batch experiments were conducted using different effluent loadings (10 to 50 %) of PW with modified BG-11 medium. The effect of PW effluent loadings on oil and COD removals from PW were studied. The progressive adaptation method was used for that purpose. Results showed that both strains can survive and grow efficiently on PW when a proper successive adaptation is provided. In general, Nannochloropsis oculata showed better growth and adaptation properties than Isochrysis galbana in the presence of PW media. Significant biomass yields were obtained at studied cultivation conditions (1.123, 1.0166, 0.856 and 0.31 g/l for Nannochloropsis oculata and 1.01, 0.899, 0.638 and 0.314 g/l for Isochrysis galbana at 0, 10, 25 and 50 % PW respectively). Nannochloropsis oculata show better oil and COD removal efficiencies than Isochrysis galbana in 10 and 25 % PW loadings and was able to remove up to 89 and 81 % oil content and 90 and 72 % COD from PW when cultivated in 10 and 25% PW loading respectively.

The performance of microbial fuel cells treating vegetable oil industrial wastewater

Abstract: The safe disposal of contaminated water has always remained a global challenge to environmentalists. To rectify wastewater pollution, current treatment technologies are not enough sustainable to meet the ever growing water sanitation needs. However, microbial fuel cell (MFC) is an emerging technology, not only treats wastewater but also generates electric energy. In this study, we investigated the electricity generation by a dual chambered MFC during wastewater treatment of vegetable oil industries from Hattar Industrial Estate Pakistan. The MFC was operated under laboratory conditions at two different temperatures (i.e. 25 and 35 °C). Briefly, anaerobic anode and aerobic cathode chambers were partitioned by a proton exchange membrane in a two-compartment MFC reactor. Phosphate buffer solution with 7 pH and wastewater from vegetable oil industries were used as electrolytes in the anode and cathode cubicles, respectively. A total of 20 wastewater samples were collected from vegetable oil industrial effluents and treated for 72 h in MFC. Results illustrate that the efficiency of MFC was increased with increase in temperature and time. The highest chemical oxygen demand (COD) removal efficiency (80%–90%) and the maximum voltage (5839 mV) were obtained at 35 °C. Furthermore, high Coloumbic Efficiencies (i.e., 33.0 and 36.5%) were observed that ratify the performance of MFCs use the maximum fraction of organic matter to produce current during treatment.

Sustainable bioremediation of Cd(II) from aqueous solution using natural waste materials: Kinetics, equilibrium, thermodynamics, toxicity studies and GA-ANN hybrid modelling

Abstract: The paper aims to provide efficient and affordable means for pollution abatement to MSME sector. In this work, the performance of some naturally available bio-waste materials, viz., leaves of jackfruit, mango and rubber plants have been attempted as biosorbents for remediation of toxic Cd(II) from aqueous solution. The biomasses have been characterized to find out the surface morphology, active surface area, presence of characteristic surface groups etc. which facilitate the biosorption process. Batch experiments are conducted to see the effects of operating parameters, viz., aqueous phase pH, initial Cd(II) concentration, adsorbent dose, time, temperature for Cd(II) ion removal onto these green biomaterials. The bioremediation mechanism was strongly pH dependent, spontaneous and followed second-order kinetics. Mass transfer, intra-particle diffusion and chemical adsorption controlled the process. Jackfruit leaf showed the best sorption performance by removing 98.72% Cd(II) from 20 mg L−1 aqueous solution at a dose of 5 g L−1 and the equilibrium adsorption capacity of 20.37 mg g−1. The bio-sorbents performed satisfactory when tested against the industrial wastewater. The toxicity effect of the cadmium ion was analysed on living animal cell and they showed morphological alteration of RBC along with clumped appearance. The cell alteration intensity reduced with the treated effluent. The natural adsorbents have comparable adsorption capacity of other green adsorbents used by different researchers. Modelling of the complex sorption process has been performed using hybrid artificial intelligence (GA-ANN) technique to predict the metal ion removal efficiency accurately and obtained results have good agreement with the experimental data with correlation coefficient (R) ranging from 0.97–0.99. All these findings have manifested application of jackfruit, rubber and mango leaves for removal of Cd(II) ions in an environmentally sustainable and friendly way.

Phytotransformation of methylene blue from water using aquatic plant (Azolla pinnata)

Abstract: The objective of the present research was to investigate the ability of the aquatic plant, Azolla pinnata as a biomass media to absorb dye (Methylene blue, MB) from water. Three different concentrations of dye were employed (5, 15, 25 mg/L) with 3 g of Azolla pinnata. The dye concentration was analysed through absorbance with a UV/Vis spectrophotometer and showed reduction from 0.09, 0.81, and 1.9 at day 0 and decreased to 0.06, 0.03, and 0.05 for 5, 15, 25 mg/L dye concentrations respectively throughout 5 days. The decolourization of 25 mg/L dye was further observed hourly within 24 h and its phytotransformation of MB dye was analysed using gas chromatography and the results show that the highest decolourization of MB blue was 85%, giving evidence that natural biomass media of floating plant (Azolla pinnata) is capable to transform and mineralize methylene blue dye and it can be successfully employed to treat dye-contaminated water

Bioaccumulation and adverse effects of persistent organic pollutants (POPs) on ecosystems and human exposure: A review study on Bangladesh perspectives

Abstract: As a developing country, Bangladesh has produced, utilized, imported, and released several types of persistent organic pollutants (POPs). However, currently we only have limited information about their eco-toxicological impacts on the ecosystem and human beings. For this reason, it is important to assess the contamination levels of common POPs (DDT, HCH, HCB, PCB, heptachlor, and ∑ PFAAs, PFOA, PFOS) and their damaging impacts on the health of people and ecosystems in Bangladesh. Admittedly, POPs are extremely resistant to natural decomposition in the environment and remain in the aquatic environment, soil, food cycles, and finally in the human body for decades even after production has stopped. POPs are proven to adversely affect people’s health. Indeed, they can disrupt endocrine, reproductive, immune and nervous systems as well as cause behavioral problems, diabetes, thyroid problems, and even cancer. As well, these contaminants interrupt the food chain and resist vital physiological functions in the long term. Therefore, investigations of environmental and ecological impacts of POPs on physiological functions of the human body are urgently required. This review paper aims to summarize the environmental toxicity levels of POPs in Bangladesh and their lethal concentrations which are creating diseases through the destruction of the human body’s vital organs. The findings will underpin future policies and lead to good, practical decisions regarding how to properly manage of POPs contamination in the ecosystem of Bangladesh and on a global scale.

Adsorption of thallium ion (Tl+3) from aqueous solutions by rice husk in a fixed-bed column: Experiment and prediction of breakthrough curves

Abstract: This study examined the use of rice husk, an inexpensive biosorbent material, for removing thallium ions (Tl + 3 ) from aqueous solutions in a continuous fixed-bed adsorption column. The impact of adsorbent bed height (from 1 to 7 cm), influent flow rate (from 0.4 × 10−3 to 1 × 10−3 m3/min), Tl + 3 concentration (from 10 to 40 g/m3), solution pH (from 5 to 12), and influent temperature (278 to 308 K) on breakthrough curves was analyzed. To identify the design parameters needed to scale up the system, the results were compared to three models, namely, Thomas, Yoon–Nelson, and Bed Depth Service Time (BDST). The experimental results were found to be well described by these kinetic models. The results confirmed the dependence of the breakthrough and saturation points on the examined variables. The system displayed excellent efficiency, achieving full (100%) removal of Tl + 3 in the first 20 min at optimum conditions. The results show that increasing the bed depth and decreasing the influent flow rate as well as the initial Tl + 3 concentration improves removal efficiency. Increasing the pH to an optimal value of ten was found to increase Tl + 3 uptake, after which any further increase of the pH inhibited adsorption due to the precipitation of Tl + 3 as a salt. Increasing the solution temperature from 278 to 298 K was found to enhance the removal percentage which indicates that the adsorption is endothermic. However, further increasing of the temperature to 308 K was found to increase the solubility of Tl + 3 in the solution which inhibits its adsorption on the adsorbent surface.

Utilization of banana peels for removal of strontium (II) from water

Abstract: Biosorbents have recently attracted significant attention for wastewater treatment. In the present work removal of Sr (II) from aqueous solution was investigated by using waste banana peels. Maximum biosorption capacity of Banana Peels Powder (BPP) was found as 41.5 mg/g at 120 rpm, pH 7, 323 K temperature, 439 μ m sized biosorbent and contact time of 10 min. Biosorption data followed the pseudo second order kinetics among other models. Studies of biosorption isotherms indicate that the Freundlich model was appropriate to describe the biosorption process compared to Langmuir model. Thermodynamic studies expressed the feasible, favourable, spontaneous and endothermic nature of the process. Desorption of strontium ions from BPP was 66.7% by using 0.1 N HNO3 at 303 K. BPP was successfully recycled for five cycles of biosorption and desorption. SEM images were confirmed the morphological changes in BPP after biosorption and desorption. BPP characterization by FTIR explores that amino, hydroxyl, carbonyl and carboxyl groups play a major role in biosorption. This data emphasized that BPP exhibited a good efficiency for the removal of strontium from aqueous solution.

Photocatalytic degradation of azo dye acid orange 7 using different light sources over Fe3+-doped TiO2 nanocatalysts.

Abstract: The photocatalytic degradation of a model azo dye acid orange 7 (AO7) by Fe3+-doped TiO2 nanocatalyst has been studied under UV, Visible ( λ >400 nm) and solar light irradiation The role of hydrogen peroxide to enhance the catalyst’s efficiency was examined The reaction pathway of complete mineralization was investigated by monitoring the temporal evolution of reaction intermediates and low molecular weight organic acids (LMWOA) as final products in solution These LMWOAs are oxidized eventually to inorganic ions such a nitrate, sulfate, oxalate etc, which are confirmed using GC–MS, UV–Vis and Ion Chromatographic analyses The optimized conditions of photocatalytic degradation were obtained for degradation under different light source The Fe 3 + -doped TiO2 showed high dye degradation efficiency under both UV (100%), visible (100%) and solar light (90%) which distinguishes Fe 3 + -doped TiO2 from materials in literature that are only efficient in particular light source for dye degradation Furthermore, the Fe 3 + doped titania photocatalysts are stable and can maintain performance up to 6 recycle use Reaction kinetics for UV and solar light induced degradation followed first order reaction whereas visible light degradation followed a zero-order reaction

Mineralization of organic carbon and nitrogen in semi-arid soils under organic and inorganic fertilization

Abstract: Although compost is added to soils to improve their nutritive status and properties; yet upon its decomposition, considerable amounts of CO2 might be emitted to the atmosphere causing hazardous environmental risks. Investigating the mineralization of compost applied to a sandy soil and a silty clay one of low organic-C content in the green house for 90 days under soil moisture contents of 75 or 100% of FC was considered. Efflux rate of CO2 decreased considerably for one day in the sandy soil after application of the compost; beyond which showed an almost constant rate. In the silty clay soil, the efflux rate decreased obviously to achieve non detectable value 3 days later. Even in soils amended with mineral N-fertilizer, CO2 emissions were valued while decreased with time. By the end of the incubation time, the rate of C-mineralization was significantly higher in the sandy soil compared with the silty clay one. Increasing soil moisture content from 70 to 100% of the field capacity led to further increases in rates of CO2 efflux as well as org-C mineralization. The amount of N mineralized in the sandy soil was 1.7 times higher than its content in the silt clay one at the FC and 1.1 times in case of 70% of FC. In conclusion, a reversible equilibrated process between decomposition of soil organic matter and buildup of more stable organic components might exist at the same time.

Ibuprofen removal from a medicinal effluent: A review on the various techniques for medicinal effluents treatment

Abstract: Ibuprofen (IBU) is a non-steroidal anti-inflammatory drug that is used for medical treatment in human and animals. Since IBU is not entirely absorbed in the body, a portion of it is obviously defecated and entered into the aqueous environment. Besides, IBU can be fed to the natural environment through pharmaceutical industry wastes. The existence of IBU in the nature can have traumatic effects on living organisms. In fact, it can widely endanger human life and the health of the natural habitat. Therefore, researchers have intended to discover methods to remove IBU from the environment or reduce its existence down to minimum. Finally they applied several different methods for doing. So, in this paper, we examine quite a few procedures to discover the advantages and disadvantages of each.

Effect of Alccofine powder on the properties of Pond fly ash based Geopolymer mortar under different conditions

Abstract: As the most widely used synthetic material on the planet, concrete poses a serious societal concern regarding its significant environmental footprint. There is a global urgency to develop innovative strategies to develop greener concrete with improved strength and durability. In recent years, scientists are interested to have OPC free concrete to reduce CO2 emission. One of the major breakthroughs is the preparation of geopolymer cement. In this paper geopolymer cement was made by activating Pond fly ash (a waste of thermal power plant) with 14 M NaOH and sodium silicate solutions. Natural Ennore sand was used to make the mortar. Alccofine powder was added during geopolymerization process, which increased the compressive strength in a similar way as silica fume. Curing was done at different temperatures in an oven and in microwave oven. Curing in microwave oven gave high compressive strength in shorter period. Powder X-ray diffraction, heat evolution profile, TG studies, compressive strength measurements and SEM studies were made to characterize the geopolymer. Durability test in sulphuric acid was conducted and it was observed that the geopolymer mortars were much more durable as compared to the control. The results have been discussed.

Effect of feed source and pyrolysis conditions on properties and metal sorption by sugarcane biochar

Abstract: Sugarcane biomass from different feed sources of sugar mill operation were used in producing biochar at different temperatures (350, 500, 650, and 800 °C) with/out steam activation at 800 °C. Feed sources included fresh cane-trash, fresh bagasse, and old bagasse collected from a pile left outside the plant for several years. Biochar yield and composition were determined and metal sorption capacity evaluated. Pyrolysis more than doubled biochar ash content which was 2 to 3 times higher for fresh cane trash and old bagasse than for fresh bagasse biochars. On the other hand, surface area of fresh bagasse activated biochars (493 m2 g−1) nearly doubled that of the old bagasse (262 m2 g−1), or fresh cane trash (204 m2 g−1) biochars. Cadmium sorption capacity increased upon activation and was an order of magnitude higher for old bagasse biochars than for fresh bagasse or fresh cane trash biochars across production temperatures (ranging from 43.4 mg g−1 to 63.8 mg g−1 compared to 0.35 mg g−1 to 0.47 mg g−1, or 4.35 mg g−1 to 6.29 mg g−1, respectively). Maximum sorption capacity for Cd and Cu was highly correlated with biochar ash content, while that of Pb correlated with biochar surface area and total sulfur content. Cu sorption capacity inversely correlated with O/C ratio and reduced significantly upon acid washing of activated 500 °C old bagasse biochar (from 32.2 mg g−1 to 14.3 mg g−1). Ash content seemed to play a decisive role in metal sorption capacity of sugarcane bagasse biochars. Overall, old sugarcane bagasse feedstock demonstrated best performance in producing biochars of higher metal sorption capacity compared to fresh cane-trash or fresh bagasse.