37 research outputs found
Application of nanofiltration for Rare Earth Elements recovery from coal fly ash leachate: Performance and cost evaluation
No full textThis work evaluated nanofiltration (NF) as a potential step in the recovery process of Rare Earth Elements (REEs) from leachates of coal combustion fly ashes. A pre-treatment step, by pH adjustment and microfiltration (MF), has been studied to separate REEs by major elements. The individual and combined effects of applied pressure (12–24 bar) and NF feed acidity (pH 1.5–3.5) on rejection of six critical REEs and permeate flux have been investigated via response surface methodology (RSM). The resulting model equations were used to develop a cost model for the recovery chain, in order to select the optimum NF operating conditions. The optimization of the REE recovery chain, including pre-treatment and NF, was done with respect to the objective of maximizing the difference between NF concentrate economic value and treatment cost. NF with an appropriate MF pre-treatment has been effective in concentrating REEs from fly ash leachate, reaching the maximum potential gain at the optimum operating conditions of 12 bar and pH 3.5
Recovery of rare earth elements from coal fly ash by nanofiltration
No full textLAUREA MAGISTRALELe terre rare sono elementi critici e strategici in una vasta gamma di applicazioni per lo sviluppo dell’economia verde. La cenere di combustione del carbone è stata proposta come fonte alternativa di terre rare, considerandone contenuto e facilità di estrazione per eluizione acida. Tuttavia, le potenziali tecnologie per il recupero di terre rare da eluato acido, le loro prestazioni e la fattibilità economica sono incerte. L'obiettivo di questo studio era quello di ottimizzare il recupero di terre rare attraverso nanofiltrazione, massimizzandone la fattibilità economica. I pretrattamenti, come la regolazione del pH e la microfiltrazione, sono stati ottimizzati aumentando la purezza di terre rare. Per valutare gli effetti delle condizioni operative (pH e pressione applicata) su reiezione e flusso della nanofiltrazione, sono stati effettuati 42 esperimenti secondo due piani sperimentali e testando quattro membrane commerciali su un eluato sintetico pretrattato. La Response Surface Methodology è stata utilizzata per modellare il flusso e la reiezione di terre rare da dati sperimentali ottenuti con diversi pH (1,5, 2,5 e 3,5) e pressioni (12, 18 e 24 bar). La reiezione di terre rare è migliorata aumentando il pH e diminuendo la pressione. Invece, il flusso di permeato è aumentato con la diminuzione del pH e l’incremento della pressione. L'analisi sul fouling della membrana ha suggerito che la diminuzione del flusso e il fouling della membrana aumentano insieme al pH e alla reiezione di ioni. Per ottimizzare le condizioni operative, è stato sviluppato un modello economico, per stimare costi di investimento e di esercizio per pre-trattamenti, nanofiltrazione e post-trattamento, nonché i ricavi della vendita delle terre rare recuperate. La combinazione ottimale di condizioni operative è stata trovata a 12 bar e pH 3,5 che ha dato la maggiore reiezione di terre rare (99,3%) e il flusso minore (15,9 LMH). Il recupero di terre rare stimato ha determinato un guadagno specifico di 0,275 /kgash. The performance of NF in the optimal operating conditions was further investigated with real leachate, showing a different performance due to the diverse ions concentrations
Influence of powdered and granular activated carbon system as a pre‐treatment alternative for membrane filtration of produced water
No full textBACKGROUND: Membrane technology is used for the treatment of produced water enabling high permeate quality to meet discharge standards or potable and irrigation water quality standards. In this study, the effect of hybrid membrane-activated carbon processes on the performance of nanofiltration (NF) and reverse osmosis (RO) membrane systems treating mixed oil and gas field produced water was investigated. Different pre-treatment alternatives including combinations of microfiltration unit and powdered activated carbon (PAC) or granular activated carbon (GAC) systems were applied prior to nanofiltration and reverse osmosis processes
Effects of the post-modification using bismuth chelate (BisBAL) on the anti-biofouling and performance properties of flat-sheet microfiltration membranes
No full textMembrane biofouling defined as the attachment and growth of microorganisms on a membrane surface has been a major problem of membrane bioreactor (MBR) technology. The anti-biofouling properties like the inhibition of bacterial adhesion of a membrane are quite significant for a long-term MBR operation. Surface modification is thought to be one of the most common approaches to improve this property. In this study, polymeric microfiltration membranes were modified by adsorption BisBAL, which is a synthesized chelate using bismuth and have a high anti-bacterial effect on various microorganisms, on the membrane surface using dip coating (DC), spin coating (SC), and low pressure-treated coating (LPtC). The purpose was to increase the surface hydrophilicity, change the surface charge, and gain the surface an anti-bacterial characteristic. It was found that the higher adsorption time, lower feed flow rate and higher spinning velocity, and pressure application increased the efficiency of the process during DC, SC, and LPtC, respectively. Furthermore, improved strategies allow the adsorption of BisBAL on the membrane surface and modified membranes has strong resistance to biofouling. Since modification resulted in a decrease in pore fouling and irreversible fouling for all type of membranes, these membranes can be novel alternatives for energy-saving MBR operation
Treatment of produced water originated from oil and gas production wells: a pilot study and cost analysis
No full textProduced water originated from oil and gas production wells was treated by a pilot-scale system including pre-treatment (chemical precipitation), pre-filtration, and post-filtration units. Pre-filtration unit consisted of sand filter, granulated activated carbon (GAC) filter, and ultrafiltration (UF) membrane. Post-filtration unit included reverse osmosis (RO) membrane unit. In this study, two different RO membranes including sea water (SW) and brackish water (BW) membranes were comparatively evaluated in terms of treatment and filtration performance. Besides, a cost analysis was conducted for a real scale RO membrane unit by using the data obtained from the pilot plant study. Average fluxes of 12.7 and 9.4 L/m(2) h were obtained by SW and BW membrane units, respectively. Higher COD and conductivity removal efficiencies were obtained by SW membrane in comparison to BW membrane. Total cost of 0.88 a,notsign/m(3) was estimated for a RO plant treating produced water with a flowrate capacity of 300 m(3)/d
Removal of emerging organic micropollutants from real hospital wastewater by modified ultrafiltration membranes
No full text<p>Membrane biofouling, characterized by the adherence and growth of microorganisms on the surface of a membrane, poses a significant challenge to the effectiveness of membrane bioreactor (MBR) technology. Enhancing anti-biofouling characteristics, particularly the prevention of bacterial adhesion to the membrane, is crucial for the sustained operation of MBR over the long term. One of the most popular methods for enhancing these characteristics is surface modification. In this study, two distinct concentrations of 150 mu M and 300 mu M of BisBAL -a chelate derived from bismuth with strong antibacterial action on a variety of microorganisms- were added to polymeric membrane solutions. Using these solutions, flat sheet (FS) and hollow fiber (HF) membranes were produced via the phase inversion method to examine their removal capabilities for micropollutants in a real hospital wastewater. Caffeine (CAF), Paracetamol (APAP) and Ciprofloxacin (CPFX) were observed as target micropollutants during a pilot-scale MBR operation. The chemical modification of the membranes enhanced the characteristics of the membrane material. Pure water flux values increased while contact angles were decreased in modified membranes When compared to bare membranes, BisBAL-added modified membranes were observed to reject CAF, APAP and CPFX more effectively. When 150 and 300 mu M BisBAL is added to FS and HF membranes, the rejection efficiencies of CAF and APAP reached their maximums, exceeding 80 %. Remarkably, CPFX rejection in the case of FS membranes added with 300 mu M reached about 30 %, whereas it surpasses 80 % in the case of HF membranes added with the same concentration. The mechanism behind the rejection of micropollutants by the membranes was determined to be adsorption. In addition to their enhanced resistance to biofouling, the new potential of these modified membranes was also demonstrated. The results suggested that membranes modified with 300 mu M BisBAL were particularly optimal for the pilot-scale MBR operations in the future, with HF membranes generally outperforming FS membranes.</p>
Quorum quenching for effective control of biofouling in membrane bioreactor: A comprehensive review of approaches, applications, and challenges
No full textIn comparison to alternative advanced wastewater treatment technologies, the main problem associated with membrane bioreactor (MBR) technology, which has become prominent in recent years, is biofouling. Within these systems, biofouling is typically the result of a biofilm layer resulting from bacterial gathering. One biological system that can be employed to interrupt the process of bacterial gathering is called 'Quorum Quenching (QQ)'. Existing QQ applications can be dassified using three main types: 1) bacterial/whole-cell applications, 2) direct enzyme applications, and 3) natural sourced compounds. The most common and widely recognized applications for membrane fouling control during MBR operation are bacterial and direct enzyme applications. The purpose of this review was to identify and assess biofilm formation mechanism and results, the suggestion of the QQ concept and its potential to control biofilm formation, and the means by which these QQ applications can be applied within the MBR and present QQ MBR studies
Process optimization for acidic leaching of rare earth elements (REE) from waste electrical and electronic equipment (WEEE)
No full textE-waste (EW) from discarded electrical and electronic devices is a potential source of rare earth elements (REEs) that might be recovered from urban and industrial wastes. REEs are essential raw materials for emerging and high technologies. China currently dominates global REE production with a proportion of 97%. To increase the independence of REE supply and eliminate the environmental impacts related to REE mining, methods for an efficient REE recovery from secondary sources like EW are needed. In this work, we examine improvements in pre-treatment and acidic leaching processes to recover REEs and other valuable metals. EW was crushed and ground prior to the sieving. The materials obtained were then subjected to acid leaching. The parameters used to optimize the conditions for leaching were as follows: acid type (HCl, HNO3, and aqua regia), particle size, and waste-to-acid ratio. The maximum leaching efficiency was obtained from the ground, sieved, and undersized part of e-waste by using HCl with a W:A of 12.5 mg/mL. The total REE concentration was 435 mg/kg. Several treatment scenarios are identified with promise for improving REE recovery at full scale in EW recovery plants and thereby advancing goals for a sustainable, circular economy
Resource Recovery from Waste, Water and Wastewaters with Membrane Technologies
No full textIn this study, critical elements (Boron (B) and Rare Earth Elements (REE)) recovery is
studied with membrane technologies. Concentrated boron can be recovered by using
different technologies. Membrane technologies such as reverse osmosis have a potential
to concentrate the boron. pH of the solution is very important if reverse osmosis is
applied. Removal of boron at pH levels of 7 and 10 increases from 80% to 97% with
reverse osmosis membranes. Another critical element is rare earth elements in the World.
Rare earth elements (REE) is a group of elements that involve lanthanides, scandium and
yttrium. A successful REE transport for wastewater was observed compared with the
concentrate flow of the acidic waste slime.This study was financially supported by The Scientific and Technological Research
Council of Turkey (TUBITAK) (Project no:117Y357), Istanbul Technical University
(ITU) Scientific Research Project (Project ID: 41893) and Eti Mining Operations General
Directorate. The authors would also like to thank Geochemistry Research Laboratory for
XRF analysi
Biofouling control based on bacterial quorum quenching with a new application: Rotary microbial carrier frame
No full textBacterial quorum quenching (QQ) is a new approach for controlling of membrane fouling in membrane bioreactors (MBRs). In this study, a novel bacterial immobilization medium named rotary microbial carrier frame (RMCF) was applied to inhibit biofilm formation in an MBR. RMCF was prepared by entrapping QQ bacteria (Rhodococcus sp. BH4) onto polycarbonate frame covered with microfiltration membrane. RMCF was submerged into the MBR using a rotational axle and rotated independently of the filtration module. QQ effect was examined with short-and long-term MBR operations. In MBRs operated with RMCF, transmembrane pressure (TMP) increasing rate was decreased with 65% efficiency. The prevention of biofouling resulted from both physical (shear forces) and biological (quorum quenching) effects of RMCF, and it was seen that RMCF could sustain its QQ effect over long-term operations. Biofilm formation inhibition by RMCF was confirmed visually using Confocal Laser Scanning Microscopy (CLSM). In addition, microbial population dynamics in MBRs were examined and it was found that RMCF had an effect on microbial diversity. The novelty of RMCF is to immobilize QQ bacteria into a rotating apparatus. With the application of RMCF, the anti-biofouling effect in an MBR had been investigated
