Life cycle analysis of the wastewater treatment system in Zabol Industrial Town: Environmental impacts, energy demand, and greenhouse gas emissions.

Use of effective environmental remediation facilities represents a crucial strategy for water reclamation and addressing the challenges of water scarcity. The objective of this study was to assess the wastewater treatment system (WWTS) in Zabol Industrial Town using the life cycle assessment method. Primary data, collected annually for a functional unit of 1 m3 of wastewater treatment, were subjected to analysis using the ReCiPe, Cumulative Energy Demand, and Intergovernmental Panel on Climate Change (IPCC) methods. Human carcinogenic toxicity (50%), freshwater ecotoxicity (13%), and marine ecotoxicity (10%) were the primary environmental impacts due to the WWTS performance. The discharge of heavy metals during sludge generation, coupled with the consumption of natural gas and oil, especially for electricity production, were pivotal factors contributing to the environmental burdens observed. Furthermore, chemical oxygen demand (COD) (56.34%), electricity consumption (>15.47%), and total phosphorous (>4.49%) significantly threatened human health and ecosystem categories, while fossil fuel consumption had the greatest impact on resources. Nonrenewable fossil fuels, namely, natural gas (47.2%) and oil (38.27%), played a predominant role in the energy provision of the system. The IPCC analysis depicted the emissions of CO2 (86.77%) and CH4 (12.16%) stemming from the process of electricity generation. Based on the outcomes of the sensitivity analysis, implementing a 10% increase in COD yielded an increment in all impacts within the range of 1.40% to 6.83%. Given Iran's geographic location and the unique climatic conditions in Zabul, use of solar and wind energy to energize the WWTS can substantially alleviate its environmental burdens. This study presents a comprehensive framework for evaluating the environmental impact, energy consumption, and carbon footprint of a WWTS. Integr Environ Assess Manag 2024;00:1-12. © 2024 SETAC.

A comprehensive framework for eco-environmental impact evaluation of wastewater treatment plants: Integrating carbon footprint, energy footprint, toxicity, and economic assessments.

The need for clear and straightforward guidelines for carbon footprint (CFP) and energy footprint (EFP) evaluations is critical due to the non-transparent and misleading results that have been reported. This study aims to address this gap by integrating CFP, EFP, toxicity, and economic assessments to evaluate the eco-environmental impacts of wastewater treatment plants (WWTPs). The results indicate that the total CFP was below 0.6 kg CO2/kg COD removed, which is attributed to CO2 offset and biogas recovery. However, site-specific EFP varied considerably from 482.7 to 2294 kgCO2/kWh due to design differences of WWTPs and their aeration and mixing energy demand (46.96-66.1%). The use of crude oil and natural gas for electricity generation significantly increased EFP, CFP, and carcinogenic human toxicity. In contrast, a combined heat and power (CHP) installation enabled energy recovery ranging from 12.09% to 65.65%. Construction costs dominated the highest share of total costs (85.43%), with indirect construction costs (42.9%) and operation labor costs (61.4%) being the primary elements in the total net costs. It is worth noting that site-specific CO2 emission factors were used in the calculations to decrease model uncertainty. However, to improve modeling reliability, we recommend modifying the regional CO2 emission factor and focusing on emerging technologies to recover energy and biogas.

Trickling filter systems for sustainable water supply: An evaluation of eco-environmental burdens and greenhouse gas emissions.

Despite the global water crisis, the significant potential of trickling filter systems as a crucial auxiliary option for sustainable water supply has received insufficient attention. Therefore, this study presents the first-ever evaluation of the environmental impacts of trickling filter application in wastewater treatment, focusing on eco-environmental burdens. Additionally, the study explores greenhouse gas emissions, energy, and exergy footprints, providing novel insights into the environmental implications of using trickling filters for wastewater treatment. The study's findings indicate that the consumption of heat and electricity in trickling filters has significant environmental impacts, particularly on land use (93.24%), freshwater/marine eutrophication (∼81.98%), and human health (45.36%). The majority of the energy required for trickling filter operation is supplied by fossil fuels (96.02%), resulting in increased greenhouse gas emissions (65.58%). The exergy of trickling filters is highly efficient, accounting for over 95% of the system's energy. Mathematical modeling reveals that anaerobic digestion and secondary clarifier have the highest energy consumption, with contributions of 94.65% and 2.63%, respectively. Construction expenses account for almost 88% of the total cost, with anaerobic digestion (42.15%) and trickling filters (35.39%) being the most costly components. The cost of treating 1 m3 of wastewater is estimated at 0.52 $/m3. Sensitivity analysis demonstrates that electricity (14.66%) and heat (18.65%) significantly impact terrestrial ecotoxicity and land use, respectively. This study presents a framework for future investigations in this field.

A comparison of nitrogen removal systems through cost-coupled life cycle assessment and energy efficiency analysis.

The global water crisis reflects the necessity of exploring the best approaches for the water supply. Therefore, for the first time, the current study compares nitrogen removal systems (NRSs) from life cycle assessment (LCA), economic, kinetic, thermodynamic, and synergistic perspectives. The assessed systems were sequential batch reactor (SBR), oxic/anoxic (OA), and oxic/anaerobic/oxic (OAO) bioreactors. Among all, the SBR configuration showed the best efficiency (98.74 %) for nitrogen removal. The environmental impacts notably presented by marine + freshwater ecotoxicity (53.76 %), and climate change categories (16.39 %), significantly because of metal emissions. Non-renewable sources supplied 95 % of total energy demand. The operation of NRSs showed the most impact on human health (63.67 %) through CH4 and CO2 emissions. The total costs significantly belonged to the construction (<86.37 %) > amortization> operation. The influent COD illustrated the most role in environmental burdens (16.44 %) based on the sensitivity analysis. The removal reaction was endothermic, physical, non-spontaneous, and followed a pseudo-second-order kinetic model (R2 > 0.98). The chemical exergy provided the major portion of the total calculated exergy (83 %). The exergetic efficiency of the system was 69 %, which was predominantly supplied by biogas (∼50.75 %). Accordingly, this study can present a stepwise guideline for further related investigations.

Green, Sustainable Synthesis of γ-Fe2O3/MWCNT/Ag Nano-Composites Using the Viscum album Leaf Extract and Waste Car Tire for Removal of Sulfamethazine and Bacteria from Wastewater Streams.

Multi-walled carbon nanotubes (MWCNTs) decorated with Ag nanoparticles (NPs) are bifunctional adsorbent nanomaterials with antibacterial activity. They can be magnetically recovered from wastewater in case of coupling with γ-Fe2O3. In this study, for the first time, an environmentally friendly technique was applied to prepare a nanocomposite (NC) material composed of γ-Fe2O3/MWCNT/Ag by using Bridgestone disposable tires and Viscum album leaves extract. γ-Fe2O3/MWCNTs/Ag NC was employed for the removal of sulfamethazine (SMT) from aqueous solutions. Under the optimized conditions determined via the Taguchi method, the highest SMT adsorption capacity of the γ-Fe2O3/MWCNT/Ag NC was measured to be 47.6 mg/g. The experimental data fitted well with the pseudo-second-order kinetic model and the Langmuir isotherm. The thermodynamic parameters implied that the adsorption process was endothermic. In addition to adsorption of the drug pollutant, the NC demonstrated a superior antibacterial activity against Gram-positive bacteria. The reusability test also showed that over 79% SMT can be removed using γ-Fe2O3/MWCNTs/Ag NC even after four adsorption cycles. Taken together, γ-Fe2O3/MWCNTs/Ag NC was proven to be a promising antibacterial nano-adsorbent for wastewater treatment.

Cost coupled removal efficiency analyses of activated sludge technologies to achieve the cost-effective wastewater treatment system in the meat processing units.

This study was conducted to distinguish the most cost-effective activated sludge-based wastewater treatment technology by focusing on removal efficiency (RE) for applying in the meat processing units. Four different wastewater treatment plants (WWTPs), namely anaerobic/anoxic/oxic (A2O), membrane bioreactor (MBR), moving bed bioreactor (MBBR), and integrated fixed-film activated sludge (IFAS) were simulated regarding the daily annual data obtained from a meat processing unit. The descending order concerning the total cost (TC) was as follows: MBR > A2O > IFAS > MBBR while it was as MBR > IFAS > MBBR > A2O based on RE. Regarding the energy and material consumption costs, the A2O and MBR were the highest and lowest cost-effective systems, respectively. However, the MBR was the best from a biological treatment cost perspective. The boilers and co-generators contributed to 75% and 25% of the produced biogas, respectively, that supplied 50% of WWTP electricity demand. Among all different influent parameters, the effect of flow rate, COD, and BOD on the TC was statistically significant. Furthermore, the TC and present worth illustrated the most sensitivity to the construction cost alteration. This research provides insights into key economic parameters for a WWTP design and application.

The feasibility of cost-effective manufacturing activated carbon derived from walnut shells for large-scale CO2 capture.

The economic potential of activated carbon (AC) synthesis from walnut shell biomass for CO2 capture was evaluated in the present study. For this purpose, the chemical activation was employed to manufacture ACs and the effect of different impregnation ratios of activation agents, comprising KOH (KH) and H3PO4 (HP), onto the properties of fabricated ACs was examined. The obtained results demonstrated that the synthesized AC by HP activation with an impregnation ratio of 1:2.5, which was identified as HP2.5, possesses the highest surface area (1512.6 m2/g), micropore volume percentage (74.65%), and CO2 adsorption (3.55 mmol/g) at 1 bar and 30 °C. Moreover, the equilibrium CO2 adsorption data for HP2.5 were better fitted with the Freundlich model, indicating the multilayer CO2 adsorption onto the heterogeneous AC surface dominantly through a physisorption process. In addition, the economic estimations revealed a cost of about $1.83/kg for the ultimate production that was significantly lower than the most of available CACs in the market. Therefore, walnut shells can be considered as a cost-effective and promising biomass source from a scale-up point of view.

Analysis of heavy metals concentration in water and sediment in the Hara biosphere reserve, southern Iran.

This study determined the concentration of heavy metals (Al, Cr, Cu, and Zn) in water and sediments at nine sites in the Hara biosphere reserve of southern Iran during the summer and winter 2010. Determination of Al, Cr, Cu, and Zn in water was carried out by graphite furnace atomic absorption spectrometer (Shimadzu, AA 610s) and in sediment by flame atomic absorption spectrometer (Perkin Elmer, AA3030). Results showed that the heavy metal concentrations in the water samples decreased in the sequence of Zn > Al > Cu > Cr, while in sediment samples were Cr > Zn > Cu > Al. Data analysis indicated that with the exception of Al, there was a Pearson's correlation coefficient between pH and Cu, Zn, and Cr at α = 0.01, 0.05, and 0.001 in sediment (in winter), respectively. There were also significant differences between heavy metals of Cr, Cu, and Zn during the two seasons (p < 0.001) in the water and sediment.

Bioaccumulation and distribution of metals in sediments and Avicenna marina tissues in the Hara Biosphere Reserve, Iran.

The metal pollution in Sediments and Avicenna marina tissues in the Hara Biosphere Reserve was monitored for Lead (Pb), Cadmium (Cd), and Nickel (Ni) with atomic absorption spectrometer. The results showed that the mean concentration of Pb, Cd, and Ni in the water and sediments were much higher than the recommended threshold limits in the most stations, also the highest means of Pb, Cd, and Ni were observed in Avicenna roots and it were 25.26 ± 4.86, 2.17 ± 0.74, and 26.72 ± 6.17 (µg g(-1)) respectively. Calculating BCF (bioconcentration factor) index illustrates that A. marina accumulates Pb, Cd, and Ni 1.62, 1.52 and 0.73 times greater than sediment levels respectively, So it can show that A. marina may be employed as a biological indicator exposure of Cd, Pb, and Ni with temporal monitoring, also the factories were main sources of metals contamination in the Hara Biosphere Reserve.