- Occurrence of perfluoroalkyl and polyfluoroalkyl substances in the water
environment and their removal in a water treatment process
- Authors: Biplob Kumar Pramanik
Abstract: Perfluoroalkyl and polyfluoroalkyl substances (PFASs) such as perfluorooctanoic acid (PFOA), and perfluorooctane sulfonate (PFOS) are found in aquatic environments worldwide. The presence of these compounds in the water environment is still unclear, even though direct or indirect discharges of these compounds from industries to the aquatic environment are the potential routes. In this paper, PFOA and PFOS contamination of aquatic ecosystems, and their removal efficiency by different water treatment processes are reviewed. Typically, PFOS and PFOA contamination levels are higher in industrialized countries than in non-industrial countries. Coagulation, sand filtration, sedimentation, oxidation and disinfection are mostly ineffective in removing PFASs from drinking and wastewater. Granular activated carbon demonstrated the removal of PFASs and the extent of removal depends on operational conditions, such as temperature, operational life period and empty bed contact time. High-pressure membrane systems are the most suitable processes for removing the PFOS and PFOA in water sources. In the high-pressure membrane, removal of those chemicals occurs through rejection via electrostatic interaction. The extent of the reduction efficiency depends on the solution chemistry of the sample; lower pH and higher calcium ion addition in the water sample enhance the reduction efficiency in the high-pressure membrane application.
- The value of fracking wastewater treatment and recycling technologies in
- Authors: Robert Hearne; Sumadhur Shakya Qingqing Yin
Abstract: The oil boom in North Dakota is aided by hydraulic fracturing, often referred to as fracking. Fracking uses a pressurized water, sand, and chemical mixture to break through layers of rock and release oil and gas. This procedure produces hundreds of truckloads of wastewater for each fracked well. In this study, we analyze the financial feasibility of a system of wastewater recycling and reuse to reduce total truck use and to conserve water supplies. We present a spatial mathematical programming model to assess the minimum cost of dealing with the potentially treatable portion of the fracking wastewater that flows back from North Dakota oil wells after fracking. Results of modeling demonstrate that mobile on-site treatment plants would be cost-effective. Both the public and private sectors have incentives to support the development of appropriate recycling technologies.
- Adsorption characteristics of Cu2+ on
NiFe2O4 magnetic nanoparticles
- Authors: Farid Moeinpour; Shohreh Kamyab
Abstract: Magnetic NiFe2O4 nanoparticles have been synthesized and used as adsorbents for copper removal from aqueous solution. The NiFe2O4 nanoparticles were characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction, and Fourier transform infrared spectroscopy. The batch removal of Cu2+ ions from aqueous solutions using NiFe2O4 magnetic nanoparticles under different experimental conditions was investigated. The effects of initial concentration, adsorbent dose, contact time, and pH were investigated. The adsorption process was pH dependent, and the maximum adsorption was observed at a pH of 6.0. Equilibrium was achieved for copper ion after 25 min. Experimental results showed that NiFe2O4 magnetic nanoparticles are effective for the removal of copper ions from aqueous solutions. The pseudo-second-order kinetic model gave a better fit of the experimental data as compared to the pseudo-first-order kinetic model. Experimental data showed a good fit with the Langmuir isotherm model.
- Kinetic modelling for heavy metal adsorption using Jordanian low cost
natural zeolite (fixed bed column study)
- Authors: Reyad Al Dwairi; Waid Omar Sura Al-Harahsheh
Abstract: Low cost Jordanian natural zeolite (ANZ1 and ANZ2) of type phillipsite-chabazite obtained from Jabal al Ataitahat south Jordan were tested experimentally as adsorbent material for the removal of lead (Pb) and lithium (Li) ions from the effluent industrial wastewater streams. The experimental breakthrough curves were obtained from fixed bed experiments and analysed using the Thomas and Yoon and Nelson kinetic models to evaluate the adsorbent performance. The rate constants for the Thomas model for the removal of lead ions using the adsorbents ANZ2 and ANZ1 were 0.201 and 0.2345 mL/min/mg, respectively. The Thomas model adsorption capacity for the removal of lead ions using the adsorbents ANZ2 and ANZ1 were 34.7 and 23.64 mg/g, respectively. The estimated rate constants for the Yoon and Nelson model for the two ANZ2 and ANZ1 were 0.038 and 0.05 min–1, respectively. The kinetic data fitted well to both models. The rate constants for the Thomas model for the removal of lithium ions using the adsorbents ANZ1 and ANZ2 were 0.134 and 0.1005 mL/min/mg, respectively, where the Thomas model adsorption capacity for the removal of lithium ions using the adsorbents ANZ1 and ANZ2 were 18.65 and 21.43 mg/g, respectively.
- Public perceptions of recycled water: a survey of visitors to the London
2012 Olympic Park
- Authors: H. M. Smith; P. Rutter P. Jeffrey
Abstract: The Old Ford Water Recycling Plant, operated by Thames Water, was used to supply non-potable recycled blackwater to some of the venues at the London 2012 Games. In an effort to learn from this experience, Thames Water commissioned a survey of visitors to the Olympic Park during the Games to explore public responses to the water recycling project. Results show a very high level of support for using non-potable recycled blackwater, both in public venues and in homes. Such findings may indicate a growing receptivity towards this technology, and show that Thames Water (and other private water companies) are well placed to encourage and even lead public discussion around the role of water reuse in the future of urban water supplies.
- Efficiency and reliability of membrane processes in a water reclamation
- Authors: Mohamed F. Hamoda; Meshari AL-Harbi Hasan AL-Ajmi
Abstract: Performance of a water reclamation plant using ultrafiltration (UF) and reverse osmosis (RO) treating 280,000 m3/d of wastewater was evaluated over 1 year. Statistical analyses were performed on flow rate, temperature, pH, total suspended solids (TSS), total dissolved solids (TDS), biochemical oxygen demand (BOD5) and total coliforms. Variations in flow rates coincided with those in temperature, both being seasonal, but plant performance was not highly influenced by such variations. The RO system recovered 85% of water flow. Data on process variables conform to a normal probability distribution and reveal the high process efficiency and reliability of UF and RO systems. Plant efficiencies were >99% for TSS, TDS, BOD5 and total coliforms. Efficiencies were the highest for TSS and total coliforms in the UF system, while they were the highest for TDS and BOD5 in the RO system. Cumulative frequency distribution analyses indicate that RO plays an important role in maintaining a stable plant performance and high quality reclaimed water. The UF system proved essential for complimenting successful performance of the RO system. Reclaimed water satisfies, at 99% frequency, the quality standards for potable water concerning TSS, TDS, BOD5 and total coliforms even though membranes have been operating continuously for 6 consecutive years.
- Preparation of composite coagulant of PFM-PDMDAAC and its coagulation
performance in treatment of landfill leachate
- Authors: Simin Li; Yongkang Lv Zhanmeng Liu
Abstract: A novel inorganic–organic composite coagulant, poly-ferric-magnesium (PFM) polydimethyldiallylammonium chloride (PDMDAAC), was prepared using FeSO4, MgSO4 and PDMDAAC as raw materials and was introduced to treat landfill leachate. The coagulation performance of the new reagent was evaluated and compared with those of other coagulants. The new reagent was characterized in terms of the analysis of ferron-timed spectroscopy, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The coagulation mechanism was investigated by measuring the ζ-potential reduction and chemical oxygen demand removal at different dosages. Coagulation experiments revealed that the new reagent exhibited better coagulation performance compared with the simple PFM and the PFM + PDMDAAC. Ferron-timed spectroscopy showed that the new reagent exhibited increased effective polymer species concentration. XRD and FTIR spectroscopy showed that the new reagent was not a simple mechanical mixing of PFM and PDMDAAC, but a composite system with inorganic–organic complex interpenetration networks. The predominant coagulation mechanism of the new reagent was charge neutralization at low dosages, as well as adsorption bridging and co-precipitation netting at high dosages, when treating landfill leachate.
- A pilot study on suspended activated sludge process augmented with
immobilized biomass for simultaneous nitrification and denitrification
- Authors: Haon-Yao Chen; Pui-Kwan Andy Hong, Ping-Yi Yang, Kok Kwang Ng, Sheng-Fu Yang, Chien-Hsien Lee Cheng-Fang Lin
Abstract: Concurrent nitrification and denitrification (CND) are natural phenomena in the soil environment that can be applied in wastewater treatment for enhanced total nitrogen removal. However, significant renovation is necessary for existing plants to equip them for nutrient removal. At a domestic wastewater treatment plant, we performed a pilot test by installing bioplates with entrapped biomass in a conventional aeration basin for CND, and investigated the effects of bioplate packing ratio (PR), hydraulic retention time (HRT), dissolved oxygen (DO) level, on/off aeration mode, and supplemental carbon and alkalinity on nitrogen removal. With the pilot aeration basin of 1.3 m3 loaded with mixed liquor suspended solids of 1,500–2,500 mg/L and bioplates at PR of 3.2% (3.2% basin volume) operated at HRT of 6 h and DO of 4–6 mg/L without supplemental carbon or alkalinity, nitrogen in the wastewater was removed to an effluent total nitrogen (TN) of 7.3 mg/L from an influent TN of 28 mg/L, achieving a specific TN removal of 25 g TN/m2/d. The bioplate, consisting of modular, robust cellulose triacetate structure carrying the biomass, shows promise in retrofitting conventional aeration basins for enhanced nutrient removal.
- Aquifer recharge with reclaimed water: life-cycle assessment of hybrid
concepts for non-potable reuse
- Abstract: Aquifer recharge with reclaimed water is a promising means to store and supply on demand reclaimed water of high quality for further non-potable reuse. The reuse applications may include indirect agricultural or landscape irrigation, saltwater intrusion barriers, subsidence mitigation or aquifer replenishment. As an alternative to high-pressure or double-membrane systems, hybrid schemes consisting of a disinfection/filtration step prior to aquifer recharge were assessed in this study regarding their environmental footprint and energy efficiency. A simplified life-cycle assessment (LCA) for a hypothetical case study in a water-scarce country was conducted to compare these hybrid schemes to a double-membrane system working under similar conditions. The results show that there is a significant margin for lowering the environmental impact, energy demand and operational costs if non-potable water quality is targeted. While the hybrid schemes outperform high-pressure membranes for these factors, land footprint and final water quality also need to be considered in the choice of solution for specific conditions.
- Synthesis of MCM-41 stabilized NZVI and its use in removal of Cr(VI) from
- Authors: Mang Lu; Yue Cheng, Jian-min Pan, Wen-jing Fan, Chuang Jiao Xiao-yu Liu
Abstract: In this study, MCM-41 stabilized nano zero-valent iron (M-NZVI) is synthesized using the rheological phase reaction method. Characterization with transmission electron microscopy validates the hypothesis that the introduction of MCM-41 leads to a decrease in aggregation of iron nanoparticles. X-ray diffraction confirms the existence of Fe0 and the strong antioxidant activity of Fe0 nanoparticles. Batch Cr(VI) reduction experiments exhibit that solution pH, M-NZVI dosage, and reaction time have significant effects on Cr(VI) removal. A high removal efficiency of Cr(VI) (84.5%) is obtained within 60 min for 100 mg/L of Cr(VI) solution at an initial pH of 6.0 and M-NZVI dosage of 0.5 g/L at 35 °C. The Cr(VI) removal rates follow modified pseudo-first-order kinetic equations. The observed removal rate constant was 0.0168/min for the M-NZVI dosage of 1.0 g/L. Our study suggests that the introduction of an innocuous stabilizer such as MCM-41 can significantly improve the performance of Fe0 nanoparticles for environmental remediation applications.
- Trends in dual water systems
- Authors: Peter D. Rogers; Neil S. Grigg
Abstract: Concerns about aging infrastructure, pressure on water supplies, and increasingly stringent wastewater discharge regulations have led water providers to consider new and innovative approaches. One such approach involves the distribution of reclaimed water through a dual distribution system in which the piping is separated into two separate and independent networks. One network is used exclusively for potable water, the other for non-potable water. This paper summarizes the results of a recently completed study sponsored by the Water Research Foundation in which a retrospective assessment of the performance of existing dual water systems was performed. Criteria for the performance assessment were established through an extensive literature review, the development of 37 case studies, site visits, feedback from workshop participants, and the creation of a classification framework that enables comparisons among similar dual systems. The study concluded that the primary motivators in using dual systems are to extend water supplies and provide more options for wastewater management. While dual systems can provide benefits such as extending the lives of existing potable water systems and deducing risk from drought, there are many issues such as storage for non-potable supplies, rate-setting, and true costs accounting that remain to be resolved.
- Geographic information system-based optimization of sewage treatment
facilities by evaluating pollution effects and governance demands
- Authors: Haixia Zhao; Xiaowei Jiang, Yawen Dong, Wen Chen Jianxin Cui
Abstract: Municipal sewage treatment facilities have important implications for cities' sustainable development and water environment protection. This study's aim is to optimize the sewage treatment facilities by evaluating pollution effects and governance demands for Huai'an City in Jiangsu province, China. The township is chosen as the evaluation unit and the spatial pattern, change trend, and environmental impact of pollution sources are analyzed to examine the demands for sewage treatment facilities in the future. By employing the ArcGIS spatial analysis tools, the spatial matching patterns between municipal treatment capacity and sewage discharge are studied. Considering the characteristics of wastewater discharge and the actual ability and designed capacity of the wastewater treatment facilities, the study area is divided into three types, including sewage treatment potential released type, sewage treatment enhanced type, and status quo maintained type. Comparing the quantity of wastewater discharged with the treatment potential capacity, direction for the construction and operation of sewage treatment facilities is proposed. Results of this study provide a scientific basis for site selection and layout optimization of municipal sewage treatment facilities.
- Energy evaluation and treatment efficiency of vacuum membrane distillation
for brackish water desalination
- Authors: Mohammad Ramezanianpour; Muttucumaru Sivakumar
Abstract: Strict environmental regulations have led to the rapid development of membrane separation technologies for the production of potable water, for industrial water supply, and for the reuse and discharge of treated wastewater. Promotion of water recycling and the provision of potable water from brackish water prevent significant negative effects on the environment and drinking water supplies. This study is intended to describe and compare a sustainable technology for brackish water treatment. Among the four configurations of the membrane distillation process, vacuum membrane distillation (VMD) produces higher flux and results in a low fouling rate. It comprises evaporation and condensation that mimics what occurs in nature. Mathematical models proposed for the VMD transport mechanisms are incorporated to predict the actual experimental flux. The response of the flux rate to various process operating parameters is demonstrated. Variation of effective parameters is investigated in terms of energy consumption. The data indicate that the permeate flux is highly responsive to the variation of pressure and temperature. VMD enables the removal of 99.9% of total dissolved solids from natural and contaminated water sources. The findings are that the quality of the permeate water from all sources was at acceptable standards for potable use.
- Water reuse and reclamation: a contribution to energy efficiency in the
- Authors: C. Schaum; D. Lensch P. Cornel
Abstract: Water and energy are two of the most important resources of the 21st century. Water is required to supply energy and, at the same time, energy is required to supply water. In urban water management, the key factor is warm water heating. Depending on the quality of the raw water, the provision of drinking water requires the application of different process technologies; the more complex the methods, the higher the energy demand. As in metropolitan areas, in particular, water consumption exceeds local availability, water pipelines are necessary with respective energy demand. The reuse of water can contribute significantly to conserve water and energy resources. Usually, the water to be reclaimed is supplied locally, making long-distance transport dispensable. By adjusting the process technology to the intended function (fit for purpose), it is possible to minimize the energy demand as well. Water use implies the input of energy (heat, chemically bound energy in form of organic matter) as well as nutrients (nitrogen, phosphorus, etc.). In the context of implementing water reuse technologies, they can also be reclaimed.
- Anaerobic membrane bioreactor for high-strength wastewater treatment:
batch and continuous operation comparison
- Authors: D. Hufnagel; S. Chang, Y. Hong, P. Wu R. G. Zytner
Abstract: The anaerobic membrane bioreactor (AnMBR) is a recent development in high-rate anaerobic bioreactors. This study assessed the treatment of high-strength wastewater by an AnMBR using batch and continuous feeding operation. The results showed that the AnMBR could establish a biomass concentration of 6–8 g/L in approximately 20 days due to retention of micro-organisms by the membrane, resulting in 86% chemical oxygen demand (COD) removal efficiency in the treatment of high-strength brewery wastewater. Batch operation was proven to be effective for an organic loading rate (OLR) up to 2 gCOD/L/day and was beneficial to the membrane filtration. However, the treatment capacity of the AnMBR with batch feeding was limited by the high instantaneous OLR during the feeding period. Compared to batch operation, continuous feeding can achieve improved stability and better effluent quality, but prolonged continuous permeation may make the membrane more susceptible to fouling. Although a critical flux of 22 L/m2/h was determined for the membrane filtration in the AnMBR tested, a decrease in the membrane permeability was still observed in the long-term filtration at a flux of approximately 10 L/m2/h.