Tannery Wastewater Research Articles

Schoenoplectus americanus as a potential phytoremediator: in vitro assessment of its ability to remove contaminants in domestic and tannery wastewater

ABSTRACT Growing industrialization and urbanization have led to increased water pollution due to the inadequate treatment and disposal of domestic wastewater (DW) and wastewater produced by industries such as tanneries (TW). These wastewaters are characterized by high concentrations of organic matter, nutrients, sulphates, chlorides and high microbial load. TW also contains phenols and chromium, which disturb and harm the ecosystem the local. The decontamination of wastewater prior to their discharge through biological tools, especially the use of species that are native to the site in need of treatment, has been described as effective and advantageous. This study evaluated the ability of Schoenoplectus americanus, a native plant species from Cordoba (Argentina), to phytoremediate local DW and TW samples at a laboratory scale. The aim was to ascertain whether this system could potentially be considered for the remediation of wastewater in real-world scenarios. S. americanus was able to tolerate pure DW and a 1/20 (v/v) dilution of TW for 30 days under hydroponic conditions. Removal rates ranging from 50% to 89% were obtained for residual organic matter (determined as chemical oxygen demand or COD), total nitrogen (TN) and total phosphorus (TP). Significant removal of total chromium (TCr) and total phenols (TPhs) was also observed in TW (85% and 98%). The number of total coliforms (TC), was reduced by about 96% and 99%. These results indicate that S. americanus is a good candidate for the phytoremediation of regional DW and TW. For this reason, it may be considered for full-scale applications in the future.

Lodo do Curtimento de couro em Argamassa: Valorização Sustentável

Purpose: This study aims to investigate the valorisation of sludge from Leather Tannery Wastewater Treatment Plants (LTWWTP) by incorporating it into cement mortars. Theoretical framework: The substantial quantity of waste generated by industries coupled with the scarcity of natural resources calls for the analysis, development, and implementation of treatment methods to recover and reuse materials, thereby minimising the environmental impact of waste disposal. The leather tanning industry, a significant polluter due to its use of hazardous and heavy materials, requires sustainable solutions for waste management. One promising approach is the incorporation of waste into cementitious matrices. Method: Three scenarios were examined: low-moisture sludge, ash obtained via incineration, and wet oxidation. Test specimens were prepared with varying proportions of cement replacement (0, 3, 5, 7, and 10%), and their flexural and compressive strengths were evaluated. Additionally, chemical analyses were conducted to assess solubility. Results and Conclusion: The results indicate that sludge can be used in small proportions without compromising the mechanical strength of the mortar. Substituting 10% cement with ash using the INC-2 incineration method improved mortar quality, exhibiting a higher compressive strength of 41 MPa and minimal water absorption (3.28%). Research implications: Drawing from these promising findings, it can be confidently asserted that utilising WWTP sludge in mortar is a practical, eco-conscious solution for civil construction. Furthermore, it is a pivotal step towards addressing the challenge of hazardous sludge disposal. Originality/value: The findings from this research will contribute to sustainable waste management practices and pave the way for responsible and eco-friendly utilisation of industrial waste in cementitious materials, thus minimising environmental burdens.

Performance evaluation of facile synthesized CA-PVA-GO composite for the mitigation of Cr(Ⅲ) and C.I. acid violet 54 dye from tannery wastewater

Untreated tannery wastewater contains a large amount of toxic metals, dyes, and other pollutants, which pose adverse effects on the ecosystem and public health. In this work, a calcium alginate-poly vinyl alcohol-graphene oxide (CA-PVA-GO) composite was prepared to remove metals and dyes, particularly Cr(Ⅲ) and CI acid violet 54 (AV54) dye, from tannery wastewater. FESEM, FTIR, and XRD analyses were applied to characterize the GO and CA-PVA-GO. Different operational variables, viz. pH (3.0–5.5 for Cr(III) and 2–7 for dye), dosage (0.164–2.46 g/L), contact time (10–60 min), initial concentration (39, 65, 98, and 201 ppm for Cr(III) and 21.5, 38.5, 54.5, and 61.75 ppm for dye), and temperature (298, 308, 318, and 328 K) were studied to evaluate the efficiency of the CA-PVA-GO composite. The optimum conditions for Cr(Ⅲ) and AV54 dye adsorption were found to be pH (5.0 and 3.0), dosage (0.82 g/L for both), and time (45 and 60 min), respectively, with 35.35 ± 1.43% and 84.63 ± 2.54% removal efficiency. The experimental data was analyzed through the Langmuir and Freundlich isotherms. The maximum adsorption capacity (qm) was observed at 173.01 and 74.68 mg/g for Cr(Ⅲ) and AV54 dye, respectively. The pseudo-second-order kinetic model was fitted better (R2 = 0.981, 0.995, 0.92, and 0.995) than first-order for AV54 dye adsorption. Thermodynamic analyses revealed that the Cr(Ⅲ) and AV54 dye adsorption processes were spontaneous and exothermic. The value of Gibbs free energy (ΔG) for Cr(III) adsorption was obtained at −7.433, −4.508, −2.626, and −1.311 kJ/mol, whereas it was −5.178, −4.867, −4.628, and −4.555 kJ/mol for dye. The values of ΔH and ΔS were −67.257 and −0.198 kJ/mol for Cr(III) and −10.852 and −0.019 kJ/mol for the dye removal. The regenerated CA-PVA-GO composite was reused successfully. Different physicochemical parameters, viz., concentration, pH, TDS, EC, BOD5, and COD of chrome tanning and dyeing effluents, were analyzed before and after the adsorption. The results of chromium and dye removal from tannery wastewater were 53.18% and 93.91%, revealing that the developed eco-friendly CA-PVA-GO composite could be an operative adsorbent for tannery wastewater treatment and possibly scaled up to an industrial level.

Phytoremediation potential of Pistia stratiotes, Eichhornia crassipes, and Typha latifolia for chromium with stimulation of secondary metabolites

Anthropogenic activities have significantly polluted the natural environments all over the world. Leather processing industries release toxic heavy metals through their effluents posing a great threat to the environment. Chromium (Cr) is the major component of tannery effluents. We designed this experiment with the aim to remediate Cr from effluents of tanneries through phytoremediation. We selected three native macrophytes i.e. Pistia stratiotes, Eichhornia crassipes, and Typha latifolia to grow in a set of Constructed Wetland systems (CWs) with a continuous supply of tannery wastewater. T. latifolia was the most efficient phytoremediator of these macrophytes as it reduced the Cr content by 96.7%. The effluent after passing through the CWs containing T. latifolia showed only 0.426 mg/L Cr content. All macrophytes showed an enhanced phytochemical activity such as total antioxidant activity (TAA), total reduction potential (TRP), total phenolic content (TPC), total flavonoid content (TFC), and DPPH radical scavenging activity (DPPH) substantially. The activation of antioxidant mechanism may have contributed towards robust defense system of these plants for survival in excessive Cr contaminated media. Also, these macrophytes showed a positive relationship in reducing Cr content from tannery wastewater. Results of this study could help in effective sustainable management of aquatic environments contaminated with metal pollutants from human activities.

Chitosan-coated coconut shell composite: A solution for treatment of Cr(III)-contaminated tannery wastewater

BackgroundTannery industry generates a large amount of Cr(III)-contaminated wastewater daily. Unless properly treated, not only this effluent contaminates the water body, but also damages the environment and threatens public health. This batch study investigates the feasibility of chitosan-coated coconut shells as a low-cost material for removing Cr(III) from tannery wastewater. Both chitosan and coconut shell (CS) waste are abundantly available from local agricultural and fishery industries. MethodsTo enhance its treatment performance for Cr(III) removal, the CS was coated with chitosan as a composite. To sustain its cost-effectiveness, the saturated composite was regenerated with HNO3. Its performance for Cr(III) removal was evaluated and compared to other low-cost adsorbents in previous work. FindingsAt the same initial concentration of 20 mg/L, it was found that the composite had a higher Cr(III) removal (97%) than the chitosan alone under the optimized conditions of 4 g/L of dose, pH 6.5, 200 rpm of agitation speed, and 1 h of reaction time. The isotherm of Cr(III) removal by the adsorbents followed the Langmuir model, while the pseudo-second order reaction was representative to simulate the adsorption data. The Cr(III) removal by the composite was based on attractive columbic forces between the negative charge of the adsorbent's surface and the positive charge of the metal cation. The negative value of ΔG thermodynamic parameter suggests the spontaneous nature of adsorption. The efficiency of machine learning regression (MLR) model was assessed in predicting the experimental data of adsorption. In spite of promising results, treated effluents still could not comply with the required limit of discharge standards of less than 0.5 mg/L mandated by local legislation. Therefore, a subsequent treatment using activated sludge is required. Overall, this work reveals a contribution of unused resources from the coconut and shrimp industries in the form of composite for protecting the aquatic environment.

Fe recovery from drinking water treatment sludge for reuse in tannery wastewater treatment: Machine learning and statistical modelling

This work experimentally and numerically studied the reusability of Fe recovered from water treatment sludge as a coagulant and compared its performance with a commercial coagulant in tannery wastewater treatment. The performance of the recycled and commercial coagulants in total suspended solid (TSS), chemical oxygen demand (COD), color, chromium (Cr3+) and turbidity removal was compared with considering pH, coagulant type and dose as independent variables. Additionally, the process was modelled by two statistical and machine learning procedures, i.e., response surface methodology (RSM) and artificial neural network (ANN). For RSM model, a 32 run experimental matrix was designed by factorial design, while ANN model was developed by a dataset extracted from the publications inclusive of the 32 experiments. The results showed Fe recovery rate of 181 mg/g dry sludge. The maximum TSS, COD, color, Cr3+ and turbidity removal by recovered and commercial coagulants were (85 %, 40 %, 42 %, 68 %, and 88 %) and (70 %, 35 %, 49 %, 64 % and 88 %) respectively. ANN COD removal model showed a good prediction in all training, validation and testing phases with R 0.891, 0.963 and 0.917 respectively. While the R for TSS, COD, color, Cr3+ and turbidity statistical models were 0.962, 0.866, 0.960, 0.962 and 0.973 respectively.

Bioremediation of tannery wastewater using UV-treated bacteria in the free and immobilized form

Bioremediation of tannery wastewater using UV-treated bacteria in the free and immobilized form

Comparison of electrocoagulation and combined electrocoagulation-electrooxidation treatment for synthetic tannery wastewaters bearing phenolic syntan

Comparison of electrocoagulation and combined electrocoagulation-electrooxidation treatment for synthetic tannery wastewaters bearing phenolic syntan

A Fenton-based approach at neutral and un-conditioned pH for recalcitrant COD removal in tannery wastewater: Experimental test and sludge characterization

The combination of raw animal skin manufacturing processes involves the use of large amounts of chemicals, resulting in the generation of complex and highly polluted tannery wastewater. In this context, the high concentration of chloride in tannery wastewater represents a crucial bottleneck. Indeed, sodium chloride, commonly used in tannery industry to prevent skin rot, increases the concentration of chlorides up to 50 %. At the same time, most of the advanced oxidation processes usually employed in tannery wastewater treatment to remove recalcitrant COD involve the use of conditioning agents, thus increasing the overall concentration of chlorides in the treated effluent. The aim of this study was to evaluate the electrochemical peroxidation process (ECP) efficiency in the treatment of tannery wastewater without changing pH, to improve Fenton technology by avoiding the use of chemicals. The influence of different electric currents on COD and color removal was investigated. The characterization of the produced sludge was conducted through FTIR, SEM and XRD analysis, exploring the morphology and composition of precipitate, depending on the applied current. Although an electrical current of 750 mA yields the highest COD and color removal efficiency (69.7 % and 97.8 %, respectively), 500 mA can be considered the best compromise because of energy consumptions. Iron oxides and hydroxides were generated during the ECP process, playing the role of coagulants through the absorption of organic and inorganic contaminants. The consumption of energy increased as a function of time and applied current; however, cost analysis showed that the electrodes contributed the most to the total cost of the process. In authors' knowledge, the application of ECP process as a tertiary treatment for the removal of recalcitrant COD in tannery wastewater represents a novelty in the literature and the results obtained can be considered as the basis for scaling up the process in future research.

Evaluation of Horizontal Subsurface Flow Constructed Wetland for Treatment of Tannery Wastewater in Kaduna, Nigeria

Tannery wastewater is often characterized by their complexities in terms of contaminants and require specialized treatment technologies. Hence, the objective of this paper is to explore the performance evaluation of a laboratory-scale horizontal subsurface flow constructed wetland (HSSFCW) in the treatment of tannery wastewater in Kaduna, Nigeria using appropriate standard techniques. Out of the tree replica systems, two were respectively vegetated with Phragmites australis and Polygonum salicifolium + Ipomoea carnea, while the last was left un-vegetated and used to treat tannery effluent. Characteristics such as Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Nitrates (NO-3), phosphates (PO43-), suspended solids (TSS) and chromium (Cr) analyzed using standard methods were used as indicators of the treatment efficiency under a 6-day Hydraulic Retention Time. The results showed that the system vegetated with Phragmites australis had the best performance in the removal of BOD, COD, NO-3, PO43- and Cr (97.9%, 94.2%, 54.4%, 44.1% and 98.4% respectively). The system vegetated with Polygonum salicifolium + Ipomoea carnea on the other hand had the best performance for SS removal (92.6%) while the system vegetated with Phragmites australis had a SS removal efficiency of 92.3%. The performance indices for unvegetated cell, Phragmites australis vegetated cell and Polygonum salicifolium + Ipomoea carnea vegetated cell were respectively, 4, 9 and 8 which shows that the cell vegetated with Phragmites australis had the best performance in the treatment of tannery wastewater. It also showed that the performance of the cell vegetated with Polygonum salicifolium + Ipomoea carnea was also comparable with that of Phragmites australis. This study demonstrated that the HSSFCW vegetated with both Phragmites australis and Polygonum salicifolium + Ipomoea carnea can effectively treat tannery wastewater. There is however a need to investigate the efficiency of the system over a longer period with consideration of microbial characteristics.

The Design of a Process for Adsorbing and Eluting Chromium (VI) Using Fixed-Bed Columns of E. crassipes with Sodium Tripolyphosphate (TPP)

Proper water resource management is a critical global objective, both privately and in business, due to the continuous deterioration of this valuable resource. Scientific research in environmental sciences has made significant progress in the development and achievements of treatment. The use of transformed E. crassipes biomass with sodium tripolyphosphate (TPP) can help to achieve this important goal. The objective of this study was to develop an experimental process for the continuous adsorption and elution of chromium (VI) using fixed-bed columns of E. crassipes biomass modified with sodium tripolyphosphate (TPP). Additionally, design tools were created, and economic viability was assessed by analyzing adsorption capacity indicators and unit production costs of different biomasses. Treatment systems were designed and constructed to remove chromium from tannery wastewater, ensuring that the levels were below the current environmental regulations of 0.05 mg/L Cr(VI). The biomass had an adsorption capacity of 98 mg/g and was produced at a low cost of 8.5 dollars. This resulted in an indicator of 11.5 g Cr(VI)/(USD) when combined with the elution processes. The proposed strategy, which utilizes entirely green technologies, enables the recovery and valorization of water resources. This makes it an effective tool for the circular economy.

Hyphenated Fenton-column packed nMnO-modified wood biochar for tannery effluent treatment: Adsorption mechanism and reusability study

Industrial wastewater contains a wide range of pollutants that, if released directly into natural ecosystems, have the potential to pose serious risks to the environment.This study aims to investigate sustainable and efficient approaches for treating tannery wastewater, employing a combination of hyphenated Fenton oxidation and adsorption processes. Rigorous analyses were conducted on wastewater samples, evaluating parameters like COD, sulphide, NH3–N, PO43−, NO3−, and Cr(VI). The performance of this adsorbent material was gauged through column adsorption experiments. A comprehensive characterization of the adsorbent was undertaken using techniques such as SEM, EDX, BET, FTIR, XRD, and LIBS. The study delved into varying operational parameters like bed depth (ranging from 3.5 to 9.5 cm) diameter (2.5 cm) and influent flow rate (ranging from 5 to 15mLmin-1). The experimental outcomes revealed that increasing the bed depth and decreasing the influent flow rate significantly bolstered the adsorption column's effectiveness. Breakthrough curves obtained were fitted with different models, including the Thomas and Yoon-Nelson models. The most optimal column performance was achieved with a bed height of 10.5 cm and a flow rate of 5mLmin-1. The combined process achieved removal efficiencies of 94.5% for COD, 97.4% for sulphide, 96.2% for NH3–N, 83.1% for NO3−, 79.3% for PO43−, and 96.9% for Cr(VI) in tannery effluent. This research presents a notable stride toward the development of sustainable and efficient strategies for tannery wastewater treatment.

Sustainable valorization of protein-rich tannery saline wastewater: Protein hydrolysate synthesis via protease and Fe3O4 porous carbon catalyst

The objective of the current study is to produce valuable protein hydrolysates (PHs) by fragmenting the proteins in protein-rich tannery wastewater (TANWWpro) through a protease-immobilized nanoporous carbon catalyst (PNPCC). The protease was isolated from the microorganism Lysinibacillus fusiformis MR1 and it contains 385 U/mL of proteolytic activity. For the immobilization of protease onto PNPCC, the ideal conditions were 2 h, pH 6–8, and 30–40 °C. FTIR, TGA, DSC, and XRD analyses were used to evaluate the protease immobilization on AGF-NPCC. For protein fragmentation, the appropriate pH, which was determined at 6, the ideal duration and temperature of 120 min at 30 °C as well as the required quantity of PNPCC were optimized. HPLC-free amino acid analysis has been used to validate the generation of PHs from TANWWpro, while electroanalytical methods including impedance spectroscopy and cyclic voltammetry have been used to establish their varied redox characteristics. Furthermore, PHs were extracted by using a Fe3O4- impregnated nanoporous carbon catalyst (Fe3O4-NPCC) and the SEM images verified the impregnation of Fe3O4 onto NPCC. Overall, employing the PNPCC and Fe3O4-NPCC, the generation and extraction of PHs from TANWWpro were both performed effectively.

Vanillic acid alleviates chromium toxicity in spinach (Spinacia oleracea L.) and lettuce (Lactuca sativa L.) plants irrigated with different levels of tannery wastewater

Vanillic acid alleviates chromium toxicity in spinach (Spinacia oleracea L.) and lettuce (Lactuca sativa L.) plants irrigated with different levels of tannery wastewater

Performance evaluation and chemical oxygen demand removal of tannery wastewater through the aerobic-anaerobic route.

With characterized for complex and maximum substance (suspended solids, broke up oil, a mixture of inorganic and chromium sulfides), tannery wastewater was subjected to a treatment process on removal of chemical oxygen demand (COD) via upstream anaerobic sludge blanket reactor where we found reduced departure efficiencies and that process limits were affected by the assortments in regular stacking rates, closeness of chromium, and sulfides. Hence, a combination of the aerobic-anaerobic hybrid reactor was set up for sequential treatment to determine possible COD reduction. This study investigated the biological degradation of tannery wastewater in a laboratory-scale sequential up-flow aerobic-anaerobic reactor. The aerobic zone at the top was packed with spherical ball-shaped polyhedral polypropylene, and the anaerobic zone at the bottom was packed medium with granular media. The aeration flow rate varied by 2 L/min, 4 L/min, and 6 L/min in the aerobic zone, and the reactor maintained an organic loading rate (OLR) of 5kg COD/m3/d. Parameters like COD and gas yield assess the performance of the reactor. The maximum COD of 86% is removed in the anaerobic zone with an aeration rate of 6 L/min, and the 1800-mL methane gas yield is measured by the 29th day.

Removal and recovery of sulphate from RO rejects tannery wastewater by double-jacketed agitated crystallizer via gypsum crystallization

This present study has assessed the resource recovery of tannery RO reject wastewater using crystallization in a double-jacketed agitated crystallization reactor under batch performance. The main objectives of this process were to remove sulphate from tannery RO reject wastewater and to recover the product as gypsum crystals. In the primary stage of initiator in crystallization, the CaCl2 initiator has better results in recovering the gypsum crystals involving chemical reactions. SEM, XRD, FTIR, and optical microscope characterize the product gypsum crystals. XRD results revealed that the uninformative size of gypsum crystals ranged between 54.61 and 61.86 nm, respectively. The experimental investigation on pH (4–12), temperature (30–180 °C), and reaction time (30–150 min) was performed. The maximum removal of sulphates from tannery RO reject wastewater was found to be 90–94 % under ideal pH 7, 30 °C for 30 min of reaction time, and 85–90 % gypsum crystal recovery, respectively. Moreover, gypsum cum Plaster of Paris was also investigated since interlocking structure and intercrystallite interactions can improve mechanical strength. It can be utilized for construction materials and ceramic mouldings for real-time applications. It could be concluded that the crystallization study helps in combating the harmful effects caused by occupying landfill sites and environmental damages.

Removal of Cr and Organic Matter from Real Tannery Wastewater via Fenton-like Process Using Commercial Nano-Scale Zero-Valent Iron

The tannery wastewater from the tanning stage (TWT) comprises organic and Cr pollutants, which can adversely affect aquatic life and have carcinogenic effects. In this study, we investigated the performance of a Fenton-like process using commercial Nano-scale zero-valent iron (nZVI) for the simultaneous removal of Cr and organic matter from real TWT. We used an experimental design to select the principal operating parameters. A Plackett–Burman design identified variables for Cr-total and COD removal, followed by a central composite design (CC-D) to determine optimal variable levels. Finally, the response surface methodology (RSM) was used to find the optimum concentration of individual variables influencing Cr-total removal. Additionally, the effect of the leather-related, co-existing substances that influenced the efficiency of the process and the possibility of recycling nZVI were explored. The inclusion of nZVI was significantly more effective at removing both Cr-total and COD (97.3% ± 5.7% and 73.9% ± 9.1%, respectively), whereas the traditional Fenton process achieved lower removal rates (55.6% ± 10.0% for Cr-total and 34.8% ± 10.9% for COD). The optimal conditions for the Fenton-like process were nZVI/H2O2 = 1.05 w/w, and pH = 2.93. We obtained the best results during the first 5 min of the reaction, which increased after 48 h of agitation and subsequent neutralization. According to the results of four consecutive cycles, nZVI exhibited high reusability (97%) without compromising its adsorption potency. XPS analysis confirmed Cr removal through the adsorption mechanism on the nZVI surface. Hence, a Fenton-like process based on nZVI can be used as a promising alternative for treating organic and Cr wastewater.

Solid dicarboxylic acid assisted deliming in beamhouse to reduce nitrogen compounds in tannery wastewater

In leather manufacturing, ammonia salts in deliming operations contribute to the significant addition of ammonia-nitrogen (NH3–N) into wastewater. Wastewater containing NH3–N serious affects aquatic life and the operations of effluent treatment plants. In this study, the strategy of reducing NH3–N released into tannery wastewater, uses non-ammonia deliming agent-solid dicarboxylic acid (malonic acid) to replace the conventional deliming agent (ammonium sulfate). Utilizing a laboratory experiment, a pilot scale test was carried out and found to be almost comparable with the former experimental work. The generated delimed wastewater, delimed pelts, and manufactured crust leathers were subjected to various physicomechanical analyses. Results revealed that the reductions of NH3–N, TKN, and hydroxyproline amounted, respectively, to 98.78%, 88.69%, and 26.9%, compared to conventional deliming agents. The other pollutants, namely TDS, BOD, COD, and EC were significantly reduced. The physicomechanical properties of the crust leathers met the standard requirements. SEM images of delimed pelt and crust leathers revealed a similar fiber structure. The wastewater emitted during deliming with malonic acid is probably an easier way to conduct effluent treatment by reducing nitrogen pollution. This investigation is a novel approach to finding a viable technology that can satisfy the need for modern leather manufacturing being done in environmentally friendly ways.

Unleashing the potential of leather waste: Biogas generation and cost savings through semi-continuous anaerobic co-digestion

Leather processing is notorious for generating substantial amounts of polluting and putrescible organic waste, usually ending up in landfills or incineration. This study aimed to assess the potential of biogas production, waste treatment efficiency, and energy and cost savings benefits when scaling up the anaerobic co-digestion of leather processing wastes. The study focused on three waste types: tannery primary sludge (TPS), leather fleshings waste (LFW), and tannery wastewater (TWW). Semi-continuous anaerobic digestion experiments were conducted using three bench-scale reactors (R1-R3) over five phases; phases I and II were the startup and stabilization. In phase III, with an organic loading rate (OLR) of 0.6 kgVS/m3/d, the R2 reactor achieved an average of 0.323 m3 methane/kgVS added/day. This performance surpassed the other reactors by 39.14% (R1) and 41.29% (R3). In phases IV and V, using TWW instead of tap water for substrate dilution at different ratios (25–100%) reduced methane yield by 3.32–11.73% compared to the reactor that used tap water. The study further revealed that a medium-sized anaerobic reactor treating tannery wastes could reduce electric energy consumption by 3.64% and thermal energy consumption by 5.20%. This showcases the energy-saving benefits of co-digesting tannery wastes rather than disposing them in landfills. Using tannery wastes instead of traditional disposal methods resulted in approximately 94.68% savings in electric consumption and 45.03% in thermal energy consumption. This study offers a promising approach for sustainable leather waste treatment, biogas production, and considerable energy and cost savings compared to conventional disposal methods like landfilling.

Evaluating the effectiveness of coagulation–flocculation treatment on a wastewater from the moroccan leather tanning industry : An ecological approach

The removal of pollutants from tannery wastewaters, which is renowned for its substantial volumes, intricate composition, and considerable hazards to human health and the environment, is a prominent research area in the field of water treatment. The aim of this study is to employ a bio-coagulant derived from Parkinsonia aculeata seeds and a bio-flocculant derived from Hibiscus esculentus to minimise the concentration of pollutants in the combined wastewater originating from tanneries. In the course of the research, a thorough physicochemical analysis of the coagulating and flocculating agents, Parkinsonia aculeata (PA) and Hibiscus esculentus (HE), was performed using techniques such as XRD (X-ray diffraction), FTIR (Fourier-transform infrared spectroscopy), and SEM-EDS (scanning electron microscopy-energy dispersive X-ray spectroscopy). This analysis aimed to determine the composition and characteristics of these biomasses. Subsequently, a comprehensive overview was conducted to summarize the various factors that influence the treatment of tannery wastewater through coagulation/flocculation. This was accomplished by manipulating the target factors and observing their impact on the removal of specific physicochemical parameters such as chemical oxygen demand (COD), electrical conductivity (EC), total chromium (Cr) and Optical density (OD). The variables that were established include pH, dosage of coagulant and flocculant, as well as the speed and duration of agitation in both the fast and slow mixing stages. The experiments were carried out while taking into account the optimal parameters, leading to the near-complete removal of all analyzed pollutants. The optimal requirements for the Parkinsonia aculeata-Hibiscus esculentus Coagulation Flocculation System involve adjusting the pH to 8, choosing concentrations of approximately 1.25 g L−1 and 0.6 g L−1 for the coagulant and flocculant respectively, maintaining a fast speed of 170 rpm for 3 min while keeping the slow agitation at around 30 rpm for 20 min. The removal rates achieved after treating tannery wastewater using the PA-HE coagulant-flocculant combination demonstrate high efficacy, with values reaching approximately 100% for TSS, 98.71% for BOD5, 99.93% for COD, 98.88% for NH4+, 98.21% for NO3−, 90.32% for NO2−, 93.13% for SO42−, 95.44% for PO43−, 96.08% for OD and 60% for total chromium. These results indicate the successful removal of a wide range of pollutants from tannery wastewater through the PA-HE treatment method. In predicting the CF treatment approach, PCA has been employed to preprocess the input data and determine the key variables that impact the process. This can streamline the modeling process and enhance the precision of the predictions.