Tannery Wastewater Research Articles

Biosynthesis and Characterization of ZnO/NiFe2O4 Nanocatalyst via Green Route Using Anacadium occidentalelinn (cashew nut) and its photocatalytic activity for the treatment of tannery wastewater under sunlight irradiation

The Anacadium occidentalelinn (cashew nut) leaves extract have been excellently utilized as a reducing as well as capping agent for the synthesis of zincoxide and nickel ferrite nanoparticles using zinc acetate, and iron (lll) chloride, nickel chloride as precursor with a different calcined temperature at the furnace and its application in the treatment of tannery wastewater. The generation of zinc oxide was proved by various characterization techniques. XRD studies displayed that a cubic phase and the average crystallite size for the intense peak measured were about 30-56nm was exhibited by the synthesized nanoparticle SEM image showed that synthesized particle are granular around 50nm and roughly spherical in shape. EDS analysis proved the elemental composition of the synthesized sample and disclosed that oxygen as well as zinc are the dominant elements. The synthesized catalyst was used in the tannery wastewater treatment also the quality parameters of tannery wastewater after treatment with the synthesized catalyst under sunlight irradiation, significantly changed and found to be within acceptable range of quality water according to (WHO). The color, odor and appearance where changed to colorless, odorless, and clear. ph, 7.4 total organic carbon (TOC), 32(mg/dm3), turbidity, 2.5(NTU) respectively. The highest efficiency of the treatment process was attained under sunlight irradiation conditions in comparison to those which were recorded under dark conditions as revealed by the result of the analysis. This procedure is safe, environmentally friendly and viable due to its fast, low cost compared to other methods.

Simultaneous removal of catechol and Cr(VI) from tannery wastewaters through Fe(III)-mediating electron transfer

Cr(VI) and catechol are common pollutants in wastewaters of tannery industry. Cr(VI) reduction by catechol results in accumulation of Cr(V)-complex and toxic o-benzoquinone. Cr(VI) reduction can be enhanced by accelerating the electron transfer from catechol to Cr(VI) using Fe(III). This electron transfer allows the continuous production of reactive oxygen species (ROS) in advanced oxidation processes, which further degrades catechol. However, the effects of catechol on Fe(III)-based Cr(VI) reduction and ROS production are not clear. In this study, the electron transfer pathway between catechol, Fe(III) and Cr(VI) was investigated along with the catechol degradation by ROS. Results show that the process of Cr(VI) reduction follows well a pseudo-second-order kinetic model, and the activation energy decreases by 4189 J/mol after electrons are transferred by Fe(III). Aqueous chromium (50 mg/L) was completely precipitated as Cr(OH)3, FexCr1-x(OH)3 or Fe(OH)3-Cr(OH)3 at Fe(III) concentration of 10 mmol/L. Residual catechol and Fe(II) in wastewater activated percarbonate, thereby producing OH for over 480 min at pH 3.0 and generating OH and CO3− for over 5 min at pH 10.0. Catechol was degraded by these ROS to butenedioic, oxalic, and formic acids, which were then mineralized to H2O and CO2. Catechol (2 mmo/L) was fully removed from wastewater with TOC removal of 37%, and the degradation was not affected by SO42− and Cl−. This study provides new insights into the removal of pollutants from wastewaters via electron transfer mediated by Fe(III), and may aid in controlling the toxic effects of Cr(VI) and catechol-like organics in natural and engineered aquatic systems.

Using the Response Surface Methodology to Treat Tannery Wastewater with the Bicarbonate-Peroxide System

A bicarbonate-peroxide (BAP) system was evaluated to improve the quality of industrial tannery wastewater using an I-optimal experimental design with four variables (temperature, initial pH, bicarbonate, and H2O2 concentration). The response variables were COD removal, ammonia nitrogen removal, and nitrate concentration. The most critical variables were optimized using a The process was carried out in 500 mL reactors, the operational volume of 250 mL, and the agitation was at 550 rpm. A new I-optimal reaction surface design at two levels (bicarbonate concentration 0.01–0.3 mol/L and H2O2 0.05–0.35 mol/L) was used to obtain the optimal data of the experimental design. Optimal conditions were validated by one-way ANOVA statistical analysis using Prism software. Temperatures above 50 °C promote the efficiency of the BAP system, and slightly acidic initial pHs allow stabilization of the system upon inclusion of bicarbonate and peroxide in the concentration of bicarbonate, which is critical for the reaction with peroxide and formation of reactive oxygen species. With the validated optimal data, removal percentages above 78% were achieved for nitrites, ammonia nitrogen, chromium, TSS, BOD, conductivity, chromium, and chlorides; for COD and TOC, removal percentages were above 45%, these results being equal and even higher than other AOPs implemented for this type of water.

Performance Optimization of Chemical and Green Coagulants in Tannery Wastewater Treatment: A Response Surface Methodology Approach

Vegetable tannery wastewater, highly laden with recalcitrant organics, is not easily treatable through biological processes. This study focuses on the use of response surface methodology in optimizing a coagulation-flocculation process for pretreatment of vegetable tannery wastewater. This study also assessed the possibility of replacing chemical coagulants such as aluminum sulphate with green alternatives such as cassava starch and orange peel powder. The effects of coagulant dosage and pH on three key wastewater quality parameters (chemical oxygen demand (COD) and total suspended solids (TSS)’s removal efficiencies as well as sludge volume index (SVI)) were also assessed. Quadratic models developed for all the three responses were adequate. The optimal conditions were attained at a pH of 3.17 and a dosage of 2.76 g/L for cassava starch coagulant, pH of 3.74 and a dosage of 5.16 g/L for orange peel powder coagulant, and pH of 6.09 and a dosage of 11.60 g/L for aluminum sulphate. The COD and TSS removal efficiencies as well as SVI achieved under these optimal conditions were 37.25%, 73.95%, and 14.80 mL/g, respectively, for cassava starch coagulant; 17.97%, 66.08%, and 19.87 mL/g, respectively, for orange peel powder coagulant; and 38.51%, 76.06%, and 29.57 mL/g, respectively, for aluminum sulphate. The outperformance of cassava starch over orange peel powder and its comparable results with aluminum sulphate makes the former a more environment-friendly alternative to aluminum sulphate for treatment of tannery wastewater.

Novel efficient capture of hexavalent chromium by polyethyleneimine/amyloid fibrils/polyvinyl alcohol aerogel beads: Functional design, applicability, and mechanisms

The harmful effects of hexavalent chromium (Cr(VI)) on the environment and human health have aroused wide public concern. In this study, bulk spherical aerogel beads (PAP) were synthesized from polyethyleneimine (PEI), protein amyloid fibrils (AFL), and polyvinyl alcohol (PVA) through green technology and its removal of Cr(VI) from wastewater was comprehensively studied. The results showed that although the bulk PAP beads (∼ 5 mm) only had an average pore size of 16.88 nm and a BET surface area of 12 m2/g, its maximum adsorption capacity for Cr(VI) reached 121.44 mg/g (at 298 K). Cr(VI) adsorption onto PAP conformed to pseudo-second-order adsorption kinetics and was endothermic. The adsorption of Cr(VI) decreased stepwise with the increase of solution alkalinity (pH = 2: 91.97%; pH = 10: 0.04%). Importantly, PAP showed high selectivity towards Cr(VI) in mixed heavy metal solutions (Cr(VI) > Pb(II) > Ni(II) > Cu(II) > Cd(II)) and good reusability (removal efficiency > 88% after 5 cycles). PAP had excellent anti-interference ability against FA and HCO3- with the overall removal rate exceeding 87% in the presence of 5 – 25 mg/L of these ions. Cations such as Na+, Mg2+, and other heavy metal ions at high concentrations could promote the removal efficiency of Cr(VI). The removal rates of Cr(VI) and Cr(III) by PAP in a tannery wastewater were 34.4% and 59.3%, respectively. Meanwhile, the removal rates of Cr(VI) in a electroplating wastewater and a contaminated soil leachate reached 84.4∼89.7%, showing high practicability. Mechanism studies revealed that electrostatic attraction, hydrogen bonding, reduction, and complexation were the main reactions for Cr(VI) removal by PAP. In general, the study of PAP provides a new insight into using bulk monolith materials for treating Cr(VI) contaminated wastewater.

Anaerobic co-digestion of agro-industrial wastes using anaerobic sequencing batch reactor for bio-energy recovery: Focus on process performance and stability of the methanogenic step

Anaerobic co-digestion of tannery wastewater (TWW) with dairy wastewater (DWW) using a two-phase anaerobic sequencing batch reactor (ASBR) was evaluated. For this purpose, laboratory-scale anaerobic digesters, one for acidogenesis and the other for methanogenesis, with 0.4 and 0.6 L of working volume, respectively, operated in semi-continuous mode, were used. The results showed that a methanogenic reactor treating the effluent acidogenic reactor (50 % TWW and 50 % DWW) exhibits the best process performances in terms of daily biogas (64.7 mL/day), methane production (461 mL/day), specific methane yield (892 mL CH4/g COD), methane content (71.2 %), and total chemical oxygen demand (TCOD) removal efficiency (85.6 %) when operated at a hydraulic retention time (HRT) of 15 days. This indicated that the addition of DWW improves the anaerobic co-digestion process, increasing biogas production (64.7 mL/day) by about 41 % as compared with anaerobic co-digestion of 100 % TWW (27.4 mL/day). The process stability of the methanogenic stage of the two-stage anaerobic digestion process was also evaluated, and the obtained result showed suitable pH (6.70), no total volatile fatty acid (TVFA) accumulation (VFA/alkalinity: 0.363), alkalinity (3350 mg CaCO3/L), and ammonia (231 mg/L) within the optimum operating range. Furthermore, high overall performance efficiency in terms of TCOD reduction (88.8 %) in the two-phase (acidogenesis and methanogenesis) anaerobic digester of 50:50 (TWW:DWW) was obtained when operated at a HRT of 18 days (3 days for acidogenesis and 15 days for methanogenesis). Anaerobic co-digestion of TWW with DWW generally resulted in increased process stabilities and performances compared to mono-digestion of TWW.

Ozonation Processes for Color Removal from Urban and Leather Tanning Wastewater

The need to ensure adequate levels of both human and environmental health protection calls for the identification of efficient wastewater treatment processes that target the removal of conventional pollutants as well as emerging contaminants, including synthetic dyes. This study explores the potential of ozone for use in the decolorization of both pretreated tannery wastewater and urban wastewater effluents. Different ozone contact times (15, 30, and 45 min) were applied to such wastewater samples at an uncontrolled (7.5–8.2) pH as well as at a pH adjusted to 10. The highest color removal efficiencies (REs) (>90%) were obtained with urban wastewater after a 45 min contact time and at pH 10. Under the same conditions, a COD RE from 31 to 51% was achieved. Even without pH adjustment, color and COD REs ranging from 81 to 92% and 39 to 41%, respectively, were obtained. A preliminary evaluation of the costs associated with the implementation of an ozonation stage within the wastewater treatment plant (WWTP) generating the urban wastewater used here was carried out. The energy cost of the ozone treatment would account for a 69% increase in the total energy cost of the WWTP, suggesting the need to identify proper strategies to enhance the cost-competitiveness of this technology.

Impact of different anode materials on electro-Fenton process and tannery wastewater treatment using sequential electro-Fenton and electrocoagulation

The influence of anode materials on the electrochemical treatment of tannery wastewater (TWW) was evaluated using Pt, Ti/RuO2–IrO2 (DSA), Ti/SnO2–Sb, Ti/PbO2, and Ti/SnO2–Sb/PbO2 electrodes. The comparison of the degradation mechanism of these electrodes in the electro-Fenton (EF) treatment was evaluated. The Ti/SnO2–Sb/PbO2 anode was efficient, with high electrocatalytic activity, stability, and reproducibility of the degradation results. Further, the study was extended to define the ability of sequential EF and electrocoagulation (EC) processes to clean TWW. The EC treatment was conducted using Al electrodes, and the performance of the combined treatment was evaluated by the removal of chemical oxygen demand (COD), turbidity, total suspended solids (TSS), sulfide, and Cr removal. The role of chlorides and sulfate salts during both treatments was evaluated by monitoring the concentration changes of these anions during the whole treatment using ion chromatography (IC). A sequential 1.5 h EF and 1 h EC treatment were applied to achieve a satisfactory degradation of (81.2 ± 3.9)% COD, >98% Cr, >99% turbidity, TSS, and sulfide removal. Additionally, the combined treatment was found to be more efficient towards the COD removal, achieving about 22.5% higher COD removal consuming almost the same amount of electrical energy.

Evaluation and Optimization of Synthesized Poly (acrylamide-co-acrylic acid) for Tannery Wastewater Treatment via RSM

Evaluation and Optimization of Synthesized Poly (acrylamide-co-acrylic acid) for Tannery Wastewater Treatment via RSM

A State-of-The-Art Technical Review on Chemically Enhanced Primary Treatment Plant

This review paper aims to provide a comprehensive assessment of chemically enhanced primary treatment (CEPT) processes in wastewater treatment plants (WWTPs). The outdated and ineffective performance of existing treatment plants has raised concerns regarding public health and environmental safety. CEPT has emerged as a promising alternative approach to enhance the efficiency and effectiveness of primary treatment. By adding chemical coagulants or precipitants to the wastewater, CEPT facilitates the aggregation and settling of suspended solids and contaminants, leading to improved treatment outcomes. This review evaluates the performance and effectiveness of different chemical coagulants, including ferric chloride (FeCl3), polyaluminum chloride (PACl), and alum, in terms of their ability to remove various pollutants such as suspended solids, turbidity, organic matter, nutrients, and emerging contaminants.
 The findings from the reviewed studies indicate that different coagulants exhibit varying efficiencies in removing specific parameters such as turbidity, total suspended solids (TSS), chemical oxygen demand (COD), and phosphorous. Alum, ferric chloride, and ferric sulfate showed effectiveness in tannery wastewater treatment, while PACl maximized the removal of macro pollutants. The use of organic carbon sources and sludge recycling demonstrated cost reductions and improved nutrient removal. CEPT was found to be effective in TSS and BOD removal, potentially allowing for compact treatment facilities and enhancing the capacity of biological treatment units. The utilization of recovered alum from water treatment sludge (WTS) in CEPT showed comparable efficiencies to fresh alum. The paper also identifies research gaps and future directions in the field of chemically enhanced primary treatment, while discussing the challenges and limitations associated with CEPT processes. While the reviewed studies provide valuable insights into the performance of different coagulants and coagulant aids, further research is necessary to assess their long-term effects and cost-effectiveness in large-scale applications. The optimal choice of coagulant depends on specific wastewater characteristics and treatment goals. Understanding and optimizing CEPT processes will contribute to the development of innovative solutions for challenges in wastewater treatment systems caused by urbanization, population growth, and emerging contaminants in the major city like Kathmandu.

Functional response of Acinetobacter guillouiae SFC 500-1A to tannery wastewater as revealed by a complementary proteomic approach

Acinetobacter guillouiae SFC 500-1 A is a promising candidate for the bioremediation of tannery wastewater. In this study, we applied shotgun proteomic technology in conjunction with a gel-based assay (Gel-LC) to explore the strain's intracellular protein profile when grown in tannery wastewater as opposed to normal culture conditions. A total of 1775 proteins were identified, 52 of which were unique to the tannery wastewater treatment. Many of them were connected to the degradation of aromatic compounds and siderophore biosynthesis. On the other hand, 1598 proteins overlapped both conditions but were differentially expressed in each. Those that were upregulated in wastewater (109) were involved in the processes mentioned above, as well as in oxidative stress mitigation and intracellular redox state regulation. Particularly interesting were the downregulated proteins under the same treatment (318), which were diverse but mainly linked to the regulation of basic cellular functions (replication, transcription, translation, cell cycle, and wall biogenesis); metabolism (amino acids, lipids, sulphate, energetic processes); and other more complex responses (cell motility, exopolysaccharide production, biofilm formation, and quorum sensing). The findings suggest that SFC 500-1 A engages in survival and stress management strategies to cope with the toxic effects of tannery wastewater, and that such strategies may be mostly oriented at keeping metabolic processes to a minimum. Altogether, the results might be useful in the near future to improve the strain's effectiveness if it will be applied for bioremediation.

Potential Removal of Chromium from Tannery Wastewater by Water Hyacinth Roots

Potential Removal of Chromium from Tannery Wastewater by Water Hyacinth Roots

A cleaner leather chemical from feather waste for reducing ammonia-nitrogen pollution and improving biological treatment efficiency of tannery wastewater

Feather waste is produced in millions of tons globally every year, resulting in a waste of biomass resources and even environmental pollution. A sustainable strategy for utilizing feather waste was proposed by preparing a clean deliming agent for ammonia-nitrogen (NH3–N) reduction in leather manufacture and biological treatment efficiency improvement of tannery wastewater. Briefly, chicken feather wastes were deeply hydrolyzed with sulfuric acid, and the optimized keratin hydrolysate (KHopt) that contained 53.6% crude protein and 41.2% amino acids, such as glutamic acid, serine, proline, leucine, phenylalanine, glycine, valine, and arginine, was obtained and used to delime limed cattle hides. The appropriate ratio of amino acids in KHopt gave KHopt a great pH-buffering capacity and maintained a stable float pH of approximately 9 throughout the deliming process. The isoelectric points of KHopt (3.8) and the limed hide (6.3) were both lower than the float pH, thereby bringing about an electrostatic repulsion between the KHopt and the hide surface, which is helpful for KHopt to penetrate and deswell the limed hide rapidly. Moreover, the KHopt deliming effectively removed calcium from the limed hide and achieved leather comparable to conventional leather for commercial applications. KHopt reduced the NH3–N concentrations of deliming effluent and tannery wastewater by 91.1% and 80.6%, respectively, compared with the conventional deliming agent (ammonium sulfate), and dramatically increased the biological treatment efficiency of tannery wastewater. The results showed that efficient and high-value use of feather waste was made by preparing KHopt for sustainable leather manufacturing.

English

Soil and water resources are often contaminated with different types of pollutants including metal ions due to indiscriminate discharge of industrial effluents. Hexavalent chromium [Cr(VI)] is one of such pollutants which has a tendency to adversely affect the environment. Microbial bioremediation is one of the cost-effective methods which might be used to remediate such metals. In current study, a bacterial strain, Basillus sp. SR18, having the potential to tolerate and reduce Cr(VI), was isolated from a soil of district Kasur Pakistan which has been repeatedly irrigated with wastewaters containing the tannery effluents. This strain had a good potential not only to tolerate the presence of Cr(VI) in the medium with MIC value of 20mM but also to completely (>90%) reduce Cr(VI) even at its initial concentration of 20 mg L-1. Basillus sp. SR18 was also effective for the Cr(VI) reduction in the presence of different concentrations of NaCl while, maximum Cr(VI) reduction was detected at pH 8.5. Moreover, SR18 was observed to reduce the Cr(VI) in varying agricultural soils and in real tannery wastewater. The reduction rate was significantly (p ≤ 0.05) different between different treatments of tannery wastewater. Bioaugmentation of three different agricultural soils with the strain SR18 resulted into a significant but varying decrease in the level of Cr(VI) with the maximum decrease in sandy soil. This study presents the significance of Bacillus sp. SR18 as a potential living source for remediation of Cr(VI) in the soils and water resources.

Valorization potential of dried tannery fleshing wastes (TFW) through pyrolysis in the leather industry: Kinetic and thermodynamic investigations

Since the moisture content of the tannery fleshing waste (TFW) of the leather industry is too high, this paper evaluates the effects of open air and greenhouse drying pretreatment on the valorization potential of these wastes by pyrolysis. The pyrolysis behavior and kinetics were studied using KAS and Starink model-free methods and the reaction mechanisms of both dried TFW samples were established by the Coats-Redfern model. The activation energy (Eα) calculated by KAS and Starink methods were similar for both samples, resulting in 121.71, 149.32 and 169.80 kJ mol−1 for TFW-OD and 155.41, 203.33 and 175.19 kJ mol−1 for TFW-GD in the first, second and third stages respectively. Moreover, the performance of two drying approaches on the behavior of TFW slow pyrolysis was studied at 500 °C and focused on biochar production to improve the feasibility of the TFW pyrolysis process, with the main goal of moving towards circular economy in the leather industry. The obtained results revealed that produced biochars are not suitable for either subsequent energetic valorization as fuels (H/C > 0.7). However, they showed a great potential for soil amendment (R50 = 0.11–0.12), long-term carbon storage (O/C < 0.4), fertilizers or sorbent for tannery wastewater treatment where adsorption of dyes is essential. Amongst the drying pretreatments, the open-air drying method proved to be the most suitable for industrial scale unit to convert TFW into economic value biochar.

Coagulation-adsorption-oxidation for removing dyes from tannery wastewater.

Dye removal from tannery wastewater is now a great concern given the ramifications for the environment in which the effluent ends up. Recently, the application of tannery solid waste as a byproduct to remove pollutants from tannery wastewater has garnered increasing attention. This study aims to extract biochar from tannery liming sludge for the removal of dye from wastewater. The activated (600 ºC) biochar was characterized by SEM (Scanning Electron Microscope), EDS (Energy Dispersive Spectroscopy), FTIR (Fourier Transform Infrared Spectroscopy), and surface area analysis utilizing the BET (Brunauer-Emmett-Teller) method and pHpzc (point of zero charges) analysis. The surface area and pHpzc of the biochar were determined as 9.29 m2/g and 8.7, respectively. The batch-wise coagulation-adsorption-oxidation was investigated for its efficacy in dye removal. The optimized conditions were as follows: the efficiency of dye, BOD (Biochemical Oxygen Demand) and COD (Chemical Oxygen Demand) were attained at 94.9%, 95.7% and 93.5%, respectively. SEM, EDS, and FTIR analyses before and after adsorption revealed that the derived biochar could adsorb dye from tannery wastewater. The adsorption behavior of the biochar fitted well to the Freundlich isotherm (R2 = 0.9987) and Pseudo 2nd order (R2 = 0.9996) kinetic model. This investigation provides a new dimension for state-of-the-art utilization of tannery solid waste as a feasible strategy to remove dye from tannery wastewater.

Removal of Colour and COD from vegetable tannery wastewater onto bone char– Effect of process parameters, adsorption mechanism, kinetics and equilibrium modelling

ABSTRACT In this study, bone char derived from head bones of cattle was used as an adsorbent in the removal of Chemical Oxygen Demand (COD) and colour from vegetable tannery wastewater. The char was characterized by proximate analysis, pHpzc, FTIR, BET surface area analysis and SEM-EDX spectroscopy. The effects of operational parameters (pH, contact time, adsorbent mass and temperature), the kinetics and isotherms of the adsorption process were investigated. Optimal conditions for maximum adsorption of COD (77.4%) and colour (98.01%) occurred at pH 2 after 60-minute contact time with 50 g of adsorbent at 25°C. The adsorption kinetics were analyzed using Elovich and the pseudo-first and – second-order models. The pseudo-second order model gave the best fit for the kinetic data. Application of the intra-particle diffusion and Boyd models to the kinetic data revealed that COD and colour adsorption onto the bone char were predominantly controlled by film diffusion. The Langmuir, Freundlich, Temkin and Redlich-Peterson isotherm models were applied. The Freundlich model best described the adsorption of COD and colour. The maximum monolayer adsorption capacities for COD and colour were 559.61 mg/g and 2011.76 Pt-Co/g, respectively. These results indicate that bone char can be an effective low-cost adsorbent in wastewater treatment.

A novel bio-adsorbent development from tannery solid waste derived biodegradable keratin for the removal of hazardous chromium: A cleaner and circular economy approach

The chromium (Cr) used in leather processing has well-known negative impacts on the environment, as the disposing of tannery effluent contains a significant amount of Cr. Alongside this, the tanning industry also generates a large amount of solid keratinous waste during the unhairing process, which also burdens to the environment. There is an urgency to recover this Cr from tannery wastewater and manage yielded solid waste by adopting an affordable and ecologically beneficial alternative. Previous studies attempted to develop bio-adsorbent from other types of bio-waste, and could not show the circular way of the reusing process of recovered Cr. Also, there needs to be more studies on bio-adsorbent preparation from tannery solid waste. This study developed a novel biodegradable film as a bio-adsorbent from keratinous waste and examined its suitability to recover Cr from tannery wastewater. The recovered Cr has been reused in the tanning process. The removal of Cr from synthetic and actual tanning effluent was optimized using a multivariate approach using Central Composite Design under Response Surface Methodology, with a removal efficiency of 91.247% and 86.972%, respectively. A desorption investigation was performed, and the analysis showed that the films could be reused, and Cr can be recovered at a pH of around 10.5. Recovered Cr from wastewater was also utilized as basic Cr sulfate in tanning. Several experimental analyses of the obtained leather demonstrated good hydrothermal stability, Cr content, and physical properties with the negligible difference compared to conventionally processed leather. Experiment on the biosorption technique was also conducted to further understand the interaction and industrial feasibility of the technology. Overall, the findings encourage the ‘use of solid waste for treatment of liquid waste’, a circular economy approach that would contribute to cleaner leather production.

Coffee spent supported Fe-Al-Zr composite: Synthesis, characterization and its adsorptive dye removal from tannery wastewater

ABSTRACT. This work was conducted to evaluate the adsorption performance of coffee spent modified Fe-Al-Zr composite. The Al2O3/Fe3O4/ZrO2 ternary oxide system was efficiently synthesized from the respective salt precursors by a two-step co-precipitation method under nitrogen atmosphere in basic condition. XRD, SEM-EDX, FTIR and ICP-OES were used to characterize the features of the adsorbents. The pH point of zero charge of the selected adsorbent was also determined. Batch adsorption experiment was conducted under different conditions such as contact time, initial concentration of dye, pH, sorbent dosage and agitation speed. The Langmuir and Freundlich, isotherms were tested to examine the adsorption behavior. The equilibrium data was well fitted to Langmuir isotherm model. The maximum adsorption capacity (qo) was 8.4 mg/g for acidic brown 75 dyes. The kinetic data correlated (R2 = 0.999) well with the pseudo second order kinetic model. To evaluate the practical applicability of the coffee spent supported nanocomposite adsorbent to real samples, effluent was collected from Batu Leather Industry. The result demonstrated 95.7% (10 mg/L) removal efficiency of the dye by the as-obtained composite indicating its potential application for environmental application.&#x0D; &#x0D; KEY WORDS: Coffee spent, Nanocomposite, Sorption, Textile dye, Immobilization&#x0D; Bull. Chem. Soc. Ethiop. 2023, 37(4), 875-889. &#x0D; DOI: https://dx.doi.org/10.4314/bcse.v37i4.6

Effect of co-culturing bacteria and microalgae and influence of inoculum ratio during the biological treatment of tannery wastewater

This present investigation is carried out to study the effect of algal and bacterial inoculum concentrations on the removal of organic pollutants and nutrients from the tannery effluent by the combined symbiotic treatment process. The bacterial and microalgal consortia was developed in laboratory setup and mixed together to perform this study. The Influence of algae and bacteria inoculum concentrations on the removal of pollutants such as Chemical Oxygen Demand (COD) and Total Kjeldahl Nitrogen (TKN) were studied using statistical optimization through Response surface methodology. For the design of experimental set up and optimization, full factorial Central composite design was used. The profiles of pH, Dissolved Oxygen (DO) and nitrate were also monitored and studied. The inoculum concentrations of microalgae and bacteria showed significant effect on Co-culturing on COD, TKN and nitrate removals as major response. The linear effect of bacterial inoculum has positive dominant influence on COD and TKN removal efficiencies. Nitrate utilization by microalgae increases with the increase in microalgal inoculum concentration. The maximum removal efficiencies of COD and TKN with 89.9% and 80.9% were obtained at optimum bacterial and algal inoculum concentrations of 6.7 g/L and 8.0 g/L respectively. These outcomes of this study are immensely favorable for maximizing the COD and nitrogen (nutrients) removal capabilities of microalgae-bacterial consortia in tannery effluent.