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Conventional leather chromium tanning requires long process time, excessive water usage and results in low float exhaustion of chrome salts. Our study aimed to eliminate the negative aspects of chromium tanning by designing a vacuum operated reaction vessel/drum and suitable production recipe for sheepskins. Tanning time decreased from 10 h to 6 h under vacuum. Float uptake was increased almost 30% according to the chrome oxide (Cr2O3) contents in leather and residual floats. Using the process water was also considerably saved. Process success was proved with Cr2O3 contents in leather and wastewater by chemical analyses after tanning operations. Shrinkage temperature (Ts) controls as hydrothermal stability indicator of collagen were also realized on the tanned skins. Pollution loads of conventional and vacuum operated chromium tanning were discussed with chemical oxygen demand (COD), total suspended solids (TSS), conductivity and salinity in the tanning baths. Physico-mechanical properties were also compared of the final products by tensile strength and tear load analyses. The results showed that vacuum operated chromium tanning was highly effective and promised for the sustainable production of leather products. [ABSTRACT FROM AUTHOR]

This study investigates the treatment of combined wastewater from Hattar Industrial Estate using Biofilm Wetlands (BW) planted with monoculture species: Eichhornia crassipes (EAC), Pistia stratiotes (WL), and Arundo donax (GR). Each species showed distinct capabilities in organic degradation, metal uptake, and pH stabilization. BW2, planted with EAC, achieved the highest total solids (TS) and total suspended solids (TSS) removal efficiencies of 66% and 65%, respectively. GR effectively reduced initial COD concentrations from 232 mg/L to 58.67 mg/L, while EAC and WL reached reductions to 72.78 mg/L and 70.67 mg/L, respectively. Overall, the plant efficiency ranking was EAC > GR > WL. These findings underscore the potential of these plant species in synergistic BW systems, highlighting their role as natural solutions for remediating complex industrial effluents. This research contributes to advancing eco-friendly wastewater treatment approaches, suggesting promising applications for sustainable practices in industrial contexts. RESEARCH HIGHLIGHTS: This research assessed the effectiveness of phytoremediation using Eichhornia crassipes, Pistia stratiotes, and Arundo donax for removing pollutants i.e. heavy metals (Cd, Pb, Ni, K, Ca, Mg, Na, Fe, Hg) nitrates, phosphates and sulfates from combined industrial wastewater of Hattar Industrial Estate Pakistan. It highlighted the potential of selected plant species' as natural treatment systems, providing crucial insights into their efficiency. Findings contribute to understanding nature-based solutions for complex industrial effluents. NOVELTY: This study harnessed the potential of three macrophytes to tackle industrial effluents, marking their debut in wastewater treatment. By championing environmentally conscious practices, it underscores the need for effective industrial wastewater management while promoting greener and more sustainable approaches within the industrial sector. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nejayote showed high-strength and complex chemical composition. • Nejayote displayed variable composition within the same maize processing facility. • High calcium recovery from nejayote was achieved through chemical precipitation. • Micro-sized substituted forms of apatite were recovered from nejayote. • Potential applications for Ca-P minerals recovered are discussed. The production of maize-based products relies on an initial step of alkaline maize-cooking (nixtamalization), which employs important amounts of lime (Ca(OH) 2). The wastewater generated during this process, known as nejayote , constitutes one of the most challenging agro-industrial effluents to treat due to its complex and highly variable physicochemical characteristics, including high concentrations of dissolved Ca2+ and highly alkaline pH values (>10). Such characteristics impose detrimental effects in systems devoted to water treatment and compound separation systems applied to this residue. In this paper, several batches of nejayote from a full-scale facility producing maize flour were thoroughly characterized to decipher the variability and magnitude parameters relevant for its treatment and potential mineral recovery. Then, a methodology for removing dissolved Ca2+ from nejayote was implemented by inducing the precipitation of calcium-phosphate (Ca-P) minerals. The results confirmed that the main chemical components of nejayote were total suspended solids (3.7 ± 0.8 gTSS/L), total chemical oxygen demand (COD) (16.8 ± 5.4 gCOD tot /L), total organic carbon (TOC) in the liquid fraction (4.1 ± 1.6 gTOC liq /L), and dissolved Ca2+ (1.5 ± 0.2 g/L), and that statistically significant differences in these and other physicochemical parameters of nejayote (pH, N species, metals and ions content, etc.) were found within the same maize-processing factory. Furthermore, it was documented that ∼ 99.9 % of the dissolved Ca2+ in nejayote can be recovered as carbonate-substituted high-purity forms of apatite and hydroxyapatite between 170 and 380 nm mean particle size. The implications of valuable Ca-P minerals recovery for a circular economy approach that allows the enhancement of water treatment and resource recovery processes are also discussed. [ABSTRACT FROM AUTHOR]

The aim of this study is to evaluate the removal efficiency and the hydraulic behavior of the 10-year-old hybrid treatment wetland (TW) system treating effluents of the IKEA® store of Catania (Eastern Sicily, Italy), under Mediterranean semi-arid climate conditions. The system is placed downstream to the conventional wastewater (WW) treatment of the store, that includes a sequential batch reactor (SBR) followed by a horizontal subsurface treatment wetland (HF) unit and two vertical subsurface flow treatment wetlands (VF1 and VF2) units. The assessment of chemical, physical, and microbiological parameters in treated WW was carried out through regular monitoring activities, occurring approximately on a monthly basis, over a 8-year period spanning from 2016 to 2023. Up to 72 samples were collected for the following parameters measurements: total suspended solids (TSS), BOD 5 , COD, total phosphorus (TP), ammonia (as NH 4), nitrate (as NO 3 -N), nitrite (as NO 2 -N), total nitrogen (TN) and E. coli. Hydraulic conductivity at saturation (K s) measurements and tracer tests were conducted to evaluate the extent of clogging and to characterize the hydraulic behavior within the HF unit. Results obtained during the entire monitoring period show the following mean and standard errors (±) removal efficiency ranges (%): TN 21(±11)-80(±9); TSS 18(±42)-95(±3); COD 28(±23)-93(±2); BOD 5 31(±10)-85(±44); TP 14(±6)-49(±19); NH 4 50(±50)-95(±3); E. coli was abated with a mean range of 3.3(±0.2)-4.8(±0.4) Ulog reduction, reaching not detectable values in most samples analyzed since 2018. The efficacy of the treatment system is assessed in the context of both national and European regulatory frameworks governing effluent discharge and water reuse standards. K s values and tracer test results agree in showing the progressive clogging of the HF unit influencing the hydraulic behavior of the unit giving useful on the management of TWs in Mediterranean area. Finally, the performance results also indicate that the overall treatment is not affected by the HF unit clogging. • Clogging evolution may eventually result in ponding phenomena and sanitation risks. • In spite of the clogging occurrence TW effluent quality meets standard requirements. • A correct TW management allows safe toilet flushing and green areas irrigation reuse. [ABSTRACT FROM AUTHOR]

• Industrial wastewater from an industrial region was treated using electrocoagulation process. • Electrocoagulation process parameters are optimized using response surface methodology. • The electrocoagulation technique reduced turbidity from 450 NTU to 56 NTU. • Total suspended solids reduced from 300 mg/L to 120 mg/L after wastewater treatment. • The operational cost of the process was estimated to range from ₹0.904/m³ to ₹2.71/m³. This study investigates the treatment of oil-contaminated wastewater with high levels of inorganic substances, suspended solids and turbidity, collected from the Haldia industrial region of India in February 2023. The wastewater, originating from industries such as chemical, petrochemical, textile, and battery manufacturing, presents a complex pollutant load that challenges traditional treatment methods. Electrocoagulation was employed as the treatment technique, with process optimization conducted using Box-Behnken design (BBD) and central composite design (CCD) for key parameters: pH, initial oil concentration, current density, and electrolysis time. The study comprehensively examined the effects of these parameters on turbidity removal. The optimal conditions were determined to be a pH of 7.5, an initial oil concentration of 275 mg/L, a current density of 17.5 mA/cm², and an electrolysis time of 20 min. Under these conditions, CCD outperformed BBD, achieving a desirability score of 93 % compared to 80 % for BBD. The process successfully reduced turbidity from 450 NTU to 56 NTU and total suspended solids (TSS) from 300 mg/L to 102 mg/L. The operation cost of the process was found to range from ₹0.904/m³ to ₹2.71/m³ as the electrolysis time increased from 0.17 to 0.5 h. The study presents a viable solution for industrial wastewater treatment in this region, aligning with the United Nations Sustainable Development Goal (UN SDG) 2030. Additionally, combining electrocoagulation with membrane filtration may enhance comprehensive pollutant removal. [Display omitted] [ABSTRACT FROM AUTHOR]

Production performance and biochemical characteristics of seaweed under varying cultivation strategies and ecological conditions provide crucial insights for improving sustainable farming practices. Therefore, this study aims to investigate the production performance and biochemical profile of sea lettuce (Ulva lactuca) under three farming systems, namely floating long-line (FLL), off-bottom long-line (OBLL), and off-bottom net (OBN), and three site-specific (Khurushkul, Nuniachora, and Sonapara) ecological conditions for a period of nine months (October 2022 to June 2023). Depending on the site suitability for different cultivation systems, 15 plots (5 FLL, 5 OBLL, and 5 OBN) were established in Nuniachora, 10 plots (5 FLL, 5 OBLL) were established in Sonapara, and 5 plots (FLL) were established in Khurushkul of the Cox's Bazar district, Bangladesh. Depending on the cultivation months, we partially harvested U. lactuca every 15–30 days once it reached 25–35 cm in length. Results showed that the gross weight biomass (GWB) of U. lactuca cultured in the FLL (F = 200.43, p < 0.001) cultivation system was 45.38% and 39.85% higher compared to OBN and OBLL, respectively. The average daily growth rate (DGR) was found to be 11%–13% higher in the FLL method (F = 236.11, p < 0.001). Location-based comparisons indicated a significantly higher (p < 0.05) U. lactuca production in Khurushkul, followed by the Nuniarchora, and the lowest was observed in Sonapara. Seasonality influenced the production performances of U. lactuca , with significantly higher (p < 0.05) growth observed from December to March due to favourable physio-chemical parameters. Multivariate analysis revealed that high salinity, pH, and nutrient concentrations positively influenced growth performances, while high temperature, turbidity, and total suspended solids (TSS) had negative effects. U. lactuca harvested from the FLL and OBN systems contained 14.3% and 9.44% higher amounts of protein (F = 36.77, p < 0.001) than the OBN system. The fatty acid analysis showed that U. lactuca from the FLL and OBN systems contained a significantly lower amount of saturated fatty acids but a higher amount of monounsaturated and n-6 polyunsaturated fatty acids compared to the OBLL system. Among the heavy metals and minerals analyzed, U. lactuca harvested from the FLL system contained significantly (p < 0.05) higher amounts of Na and K and lower amounts of Pb, Cr, Co, and Fe. The findings of the present study underscore the superiority of the floating long-line cultivation system for U. lactuca , highlighting its potential for sustainable farming practices to address global food security and utilization in various industrial applications. • Growth performances and biochemical profiles of Ulva lactuca were evaluated under three cultivation systems • Site-specific ecological factors significantly influenced the production performance and biochemical profile of U. lactuca • Gross weight biomass of U. lactuca was 45.38% higher in the floating long line (FLL) system than the off-bottom net system • U. lactuca harvested from the FLL system contained significantly lower amounts of heavy metals • The findings of the present study underscore the superiority of the FLL cultivation system for U. lactuca [ABSTRACT FROM AUTHOR]

Manure suspended solids and pathogens negatively contribute to many environmental aspects including water contamination, air pollution, greenhouse gas emissions (GHG), unpleasant odor and spread of pathogenic bacteria. Production of an environmentally friendly flocculant with dual function of sterilization and flocculation of the manure solids and particles is a challenge. Here, gelatin (Gel) was covalently modified with non-vinyl monomer, glycidyltrimethylammonium chloride (GMTA) to form poly-cationic Gel (GMTA@Gel) via a single step functionalization under mild conditions. The developed cationic Gel (GMTA@Gel) showed positive zeta potential (ZP) value > +50 mv in a wide pH range (3−10), excellent removal efficiency of total suspended solids (97 %) and E. coli (98 %) in dairy wastewater, and disinfection capability of microorganisms adsorbed on the Gel, which were confirmed by elemental analysis and cell rupture analysis. The developed Gel-based flocculant showed 95 % removal of both MSS and E. coli from real manure wastewater collected from manure ponds of dairy farms in Central Valley, California and reduced 97 % of volatile solids, which suggest its contribution in reducing GHG emissions. The developed GMTA@Gel flocculant has the advantages of environmental protection, excellent removal efficiencies for anionic contaminants and enhanced coagulation effect on suspended bacterial cells and particles which suggest GMTA@Gel to be applied on removal of suspended anionic suspensions (particles or cells) from various wastewater sources. [Display omitted] • Polycationic gelatine flocculant was fabricated via a single step grafting to non-vinyl monomer. • Self-propagation of GMTA plays the main role in polycationic chains grafted on gelatine surface. • Poly-cationic gelatine show robust cationic charge at wide pH range. • GMTA@Gel exhibited 95 % removal of manure suspended solid and E. coli cells from real wastewater. • The GMTA@Gel exhibited 25 % enhanced flocculation efficiency compared to commercial flocculants. [ABSTRACT FROM AUTHOR]

• Optimal aeration placement within a 4-meter range improves efficiency and enhances water quality. • Addressing dissolved oxygen stratification with gentle water agitation promotes species well-being. • Seasonal ARIMA forecast integration enables informed decisions for energy optimization in aquaculture. Aquaculture relies significantly on effective aeration systems to ensure optimal conditions for aquatic organisms. This 96-day study investigates the dynamic relationship between Oxygen Transfer Rates (OTR) and seasonal variations, with a specific focus on the impact of seasonal dynamics and the placement of paddle wheel aerators. The study recognizes the pivotal role of Total Dissolved Solids (TDS) and Total Suspended Solids (TSS) as key water quality parameters influencing aeration efficiency. A series of water circulation experiments were conducted at regular intervals to assess mixing rates, revealing a nuanced trajectory ranging from 27.05 to 14.22 m³/kWh. The study scrutinized the influence of TDS and TSS on these rates. Additionally, water velocity variations, ranging from 0.45 to 1.67 m/s, were examined, highlighting density-dependent changes, particularly evident post four weeks of operation. Oxygen stratification analysis provided insights into deviations in Dissolved Oxygen (DO) concentrations, with particular attention to climatic aberrations. Rigorous statistical analyses, including chi-squared, Pearson correlation, Gaussian distribution checks, and student's t -tests, validated the methodological robustness and data reliability. Employing a Seasonal Auto Regressive Integrated Moving Average (SARIMA) model, the study achieved a remarkable 97 % accuracy in forecasting DO levels for the subsequent 96 days. Real-time validation, complemented by a Chi-square goodness of fit test, reaffirmed the model's reliability, establishing congruence between observed and forecasted values. This research underscores the critical roles of strategic aerator placement and seasonal considerations in optimizing pond aeration efficiency, providing substantive insights for the sustainable management of aquaculture ecosystems. [Display omitted] [ABSTRACT FROM AUTHOR]

Regulating internal and external phosphorus (P) holds a predominant position in eutrophication management of lakes and other water bodies, with less emphasis on controlling nitrogen (N) due to the presence of N 2 -fixing cyanobacteria. Nonetheless, external N influxes may stimulate the proliferation of non-N 2 -fixing cyanobacteria, thereby fostering cyanobacteria blooms during summer seasons. To elucidate the significance of N regulation, a two-factor orthogonal experiment was performed to study the influences of external N input on the efficacy of lanthanum-modified bentonite (LMB), a sediment capping material for P immobilization. At the experimentation ends, the total suspended solids (TSS), organic suspended solids (OSS) concentrations and optical attenuation coefficient (K d) in the LMB + N treatment were 7.34, 8.65 and 5.20 times higher, respectively, compared to the LMB treatment. The total nitrogen (TN), total phosphorus (TP) and soluble reactive phosphorus (SRP) concentrations in the LMB + N treatment were 3.02, 1.30 and 0.60 times higher, respectively, than those in the LMB treatment. However, TP and SRP in the LMB + N treatment were 46.98% and 54.93% lower, respectively, compared to N treatment. The chlorophyll a (Chl a) concentration of algae in the LMB + N treatment was observed to be 2.86 times higher compared to the LMB treatment, and 17.13% lower compared to the N treatment. The biomass of cyanobacteria accounted for more than 95% of algae in the LMB + N treatment and N treatment. Furthermore, the photosynthetic performance of algae in the N treatment increased significantly, compared to the LMB + N treatment. Our results indicated that external N influxes significantly reduce the efficacy of LMB to control P and algae. Thus, the implementation of more stringent N control policies holds great significance in the eutrophication control. [Display omitted] • Nitrogen facilitated non-N 2 fixing cyanobacteria blooms even under LMB. • Algae showed relatively high biomass but low chlorophyll an under LMB and nitrogen. • Algae proliferation enhanced phosphorus release from sediment under LMB. • Implementing stricter nitrogen regulation holds great significance. [ABSTRACT FROM AUTHOR]

The growing demand for sustainable sewage treatment requires technologies that overcome the limitations of energy-intensive and chemical-dependent systems. This study presents an innovative solution addressing both environmental and operational challenges with the design and development of an Up-flow Compact Constructed Wetland (UCCW) based Sewage Treatment Plant (STP). This system integrates preliminary, primary, secondary, and tertiary treatment units into a single setup. The performance of UCCW based STP was evaluated over 720 days under different Hydraulic Retention Times (HRTs), considering seasonal variations in both rectangular and circular configurations. The system achieved significant pollutant removal as Total Suspended Solids (96%), Chemical Oxygen Demand (86%), Biochemical Oxygen Demand (90%), Total Nitrogen (70%), Total Phosphorus (65%), and Fecal Coliforms (99%) at a 36-h HRT. These parameters meet discharge standards, except FC, which requires disinfection for safe reuse and recycling. Further, Response Surface Methodology (RSM) and Monte Carle Simulation of UCCW based STP confirmed optimal and reliable performance at a 36-h HRT. Compared to conventional treatment technologies, the UCCW based STP demonstrated higher efficiency, a smaller footprint (1m2/KLD), better operational flexibility, cost-effectiveness, and minimal operation & maintenance to make it sustainable for decentralised treatment. [Display omitted] • Patented UCCW-STP integrates all units in a single system for community-level treatment. • Achieved TSS, COD, BOD, TN, TP, and FC removal: 96%, 86%, 90%, 70%, 65%, and 99%. • Evaluated over 720 days, showing robust performance across seasons and HRTs. • RSM optimized conditions for maximum efficiency and resource minimization. • Cost-effective, nature-based solution superior to conventional methods. [ABSTRACT FROM AUTHOR]