Development of a novel submerged membrane electro-bioreactor for wastewater treatment

The principle objectives of this research were to design and investigate a novel approach to generate an excellent quality effluent, while minimizing the size of the treatment unit and energy consumption. To achieve these objectives a submerged membrane electro-bioreactor (SMEBR) was designed and its performance was investigated. Membrane processes, electrokinetic phenomena, and biological processes take place simultaneously leading to the control of the problem of membrane fouling which has been considered one of the major challenges to widespread application of membrane bioreactor technology. This design is the first attempt to combine electrokinetic principles, using electro-coagulation (EC) processes and submerged membrane bioreactor in one reactor vessel. Both water quantity and quality were monitored through different experimental phases to verify the feasibility of the SMEBR system for wastewater treatment under various operating conditions. Firstly, a preliminary experimental phase was conducted on a small-scale electro-bioreactor (without the operation of the membrane module) to identify the best electrokinetic conditions in terms of the appropriate current density so as not to impede the biological treatment, and to determine the best exposure time of DC when it should be applied intermittently in the SMEBR system. DC field of 1 V/cm with an operational mode of 15 minutes ON/45 minutes OFF of DC power supply were found to be the adequate electrical conditions to operate the SMEBR system. Two different anode materials--iron and aluminum--were used to validate the SMEBR system for wastewater treatment. At the operating mode of 15 minutes ON/45 minutes OFF, the applied DC field in the SMEBR system enhanced the membrane filterability up to 16.6% and 21.3% using iron and aluminum electrodes respectively. However, the significant improvement in membrane filterability was 52.5% when using an aluminum anode at an operational mode of 15 minutes ON/105 minutes OFF, which indicated that the operational mode of DC supply is a key parameter in the operation of a SMEBR system. In terms of pollutants removal, the overall removal efficiency for COD was greater than 96% and greater than 98% for phosphorus. In conjunction, the removal of NH 3 -N was on average 70%. It should be emphasized that the phosphorous removal efficiency was higher than other studies on MBR without the use of electrokinetics. Furthermore, the effluent of the SMEBR treatment, using synthetic wastewater, had no color and no odor. The designed SMEBR system may find a direct application in the treatment of various wastewaters, including sewage, without an extensive pretreatment. Such a solution is required by several small municipalities, mining areas, agriculture facilities, military bases, and in cold regions. Finally, such a compact hybrid system can easily be adapted to a mobile uni

Clayey soil amendment by hydrophilic nano bentonite for landfill cover barrier: a case study

Methane and carbon dioxide are of major concern as greenhouse gases; the landfills have the problem of controlling these gases. Al Akaider in Jordan is the second biggest landfill suffers controlling gases as it lacks a cover design system. In this work, the main goal is to investigate the appropriateness of amended expansive clayey soil in Irbid as a cover barrier. The expansive soil is unwanted in construction projects, thus the modification of this expelled soil enables using it as a low cost landfill cover barrier. In this research, the effect of adding nano-clay material (Hydrophilic Nano Bentonite) on the geotechnical characteristics, hydraulic conductivity, and gas transport coefficients of the clayey soil are studied. The soil samples were obtained from Irbid city. Unconfined compressive strength and free swelling tests were performed on soil samples with different percentages of nano-clay added in the range (0.1% to 1.2%) by weight. The results indicated that the addition of nano-clay at low percentages increases the strength of expansive soil up to 315 kPa at 0.6% of nano-clay and the swelling potential decreased dramatically with the addition of nano-clay. The optimal percent of nano-clay was found to be 0.6%. The intrinsic permeability of the amended soil was 6.03×10–15 m2. The average values of fluid transport coefficients were determined at 25 °C. The hydraulic conductivity for water was about 6.5×10–10 m/s. Gas conductivity coefficients for CO2 and CH4 were 5×10–9 m/s and 2.5×10–9 m/s respectively. Gas diffusion coefficients for CO2 and CH4 were 3×10–6 m2/s and 4×10–6 m2/s respectively. The results obtained in this research showed compatibility with standards conducted on geosynthetic clay liner (GCL), consequently the amended Irbid soil investigated, can be used as a cover barrier in Al Akaider landfill. These findings can also be generalized to landfills with similar conditions

Impact of applying electrocoagulation pre-treatment step on grey water treatment by submerged membrane bioreactor

[abstract not available

A comparison between iron and mild steel electrodes for the treatment of highly loaded grey water using an electrocoagulation technique

In the last years, the electrocoagulation (EC) process has been widely used as a potential technique for grey water treatment. However, only a few studies have focused on treating highly loaded GW (HLGW) by EC. In this study, the EC technique was used to compare iron and mild steel electrodes for the treatment of HLGW under different current densities (CDs) (5, 10, 15, and 20 mA/cm2) during 10 min of EC time. The performance criteria included chemical oxygen demand (COD) and turbidity removal efficiencies, current efficiency, energy consumption, and operational costs. It was found that EC using iron or mild steel can be effective electrodes for removing high levels of COD and turbidity from HLGW. At optimum conditions, the study demonstrated that at a CD of 5 mA/cm2, mild steel-based electrodes reduced COD by 86.5% while iron-based electrodes achieved 85.3% reduction at 10 mA/cm2. In conjunction with these removals, the turbidity removals were 92% and 94% achieved by steel and iron electrodes, respectively. The current efficiency of all the conducted experiments exceeded 90% but was generally higher for iron electrodes. At optimum conditions, analysis of operating costs in terms of energy consumptions and electrode materials requirements were 0.054 $/m3 and 0.097$/m3 achieved by steel and iron electrodes, respectively. Thus, mild steel-based electrodes are considered superior to iron electrodes. Based on the obtained results, the study recommends that further investigations should give attention to the effect of metal alloy type or physical properties of electrodes as performance criteria and designing aspects when studying EC technology for HLGW treatment due to its notable effect on removal efficiency and operational costs

Investigating the potential of using solid waste generated from stone cutting factories for phenol removal from wastewater: A study of adsorption kinetics and isotherms

Remarkably toxic, phenol requires efficient elimination from water. This study investigates the utilization of solid waste generated by stone-cutting factories for extracting phenol from wastewater. The solid waste underwent thermal treatment at 105 °C for 3 h for characterization. Batch adsorption experiments systematically assessed parameters like phenol concentration, adsorbent mass, contact time, temperature, and pH. Optimal removal transpired at pH 7.5, reaching equilibrium within 4 h. Phenol uptake equilibrium values were 8.1, 13.3, 16.2, 20.2, and 28.1 mg/g for initial concentrations of 50, 100, 150, 200, and 300 mg/L, respectively using 1 g of adsorbent at ambient temperature. The Langmuir model fit acceptably, yet the Freundlich model surpassed it. The most suitable kinetics model for phenol adsorption was the pseudo-second-order. The nature of the adsorption process was endothermic. Importantly, this study pioneers the promising application of solid waste generated from stone-cutting factories as an adsorbent material for effective phenol removal, offering a sustainable approach. Notably, no previous study has been conducted on phenol removal from wastewater using this specific adsorbent, rendering this work pivotal in exploring its potential. This solid waste presents an economical, readily available, and environmentally benign material for the adsorption process, expected to exhibit substantial adsorption capacity

Global variation in postoperative mortality and complications after cancer surgery: a multicentre, prospective cohort study in 82 countries

© 2021 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 licenseBackground: 80% of individuals with cancer will require a surgical procedure, yet little comparative data exist on early outcomes in low-income and middle-income countries (LMICs). We compared postoperative outcomes in breast, colorectal, and gastric cancer surgery in hospitals worldwide, focusing on the effect of disease stage and complications on postoperative mortality. Methods: This was a multicentre, international prospective cohort study of consecutive adult patients undergoing surgery for primary breast, colorectal, or gastric cancer requiring a skin incision done under general or neuraxial anaesthesia. The primary outcome was death or major complication within 30 days of surgery. Multilevel logistic regression determined relationships within three-level nested models of patients within hospitals and countries. Hospital-level infrastructure effects were explored with three-way mediation analyses. This study was registered with ClinicalTrials.gov, NCT03471494. Findings: Between April 1, 2018, and Jan 31, 2019, we enrolled 15 958 patients from 428 hospitals in 82 countries (high income 9106 patients, 31 countries; upper-middle income 2721 patients, 23 countries; or lower-middle income 4131 patients, 28 countries). Patients in LMICs presented with more advanced disease compared with patients in high-income countries. 30-day mortality was higher for gastric cancer in low-income or lower-middle-income countries (adjusted odds ratio 3·72, 95% CI 1·70–8·16) and for colorectal cancer in low-income or lower-middle-income countries (4·59, 2·39–8·80) and upper-middle-income countries (2·06, 1·11–3·83). No difference in 30-day mortality was seen in breast cancer. The proportion of patients who died after a major complication was greatest in low-income or lower-middle-income countries (6·15, 3·26–11·59) and upper-middle-income countries (3·89, 2·08–7·29). Postoperative death after complications was partly explained by patient factors (60%) and partly by hospital or country (40%). The absence of consistently available postoperative care facilities was associated with seven to 10 more deaths per 100 major complications in LMICs. Cancer stage alone explained little of the early variation in mortality or postoperative complications. Interpretation: Higher levels of mortality after cancer surgery in LMICs was not fully explained by later presentation of disease. The capacity to rescue patients from surgical complications is a tangible opportunity for meaningful intervention. Early death after cancer surgery might be reduced by policies focusing on strengthening perioperative care systems to detect and intervene in common complications. Funding: National Institute for Health Research Global Health Research Unit