Water bodies are increasingly contaminated with a diversity of organic micropollutants (OMPs). This impacts the quality of ecosystems due to their recalcitrant nature. In this study, we assessed the ...removal of OMPs by spent mushroom substrate (SMS) of the white button mushroom (
Agaricus bisporus
) and by its aqueous tea extract. Removal of acesulfame K, antipyrine, bentazon, caffeine, carbamazepine, chloridazon, clofibric acid, and
N, N
-diethyl-
meta
-toluamide (DEET) by SMS and its tea was between 10 and 90% and 0–26%, respectively, in a 7-day period. Sorption to SMS particles was between 0 and 29%, which can thus not explain the removal difference between SMS and its tea, the latter lacking these particles. Carbamazepine was removed most efficiently by both SMS and its tea. Removal of OMPs (except caffeine) by SMS tea was not affected by heat treatment. By contrast, heat-treatment of SMS reduced OMP removal to < 10% except for carbamazepine with a removal of 90%. These results indicate that OMP removal by SMS and its tea is mediated by both enzymatic and non-enzymatic activities. The presence of copper, manganese, and iron (0.03, 0.88, and 0.33 µg L
-1
, respectively) as well as H
2
O
2
(1.5 µM) in SMS tea indicated that the Fenton reaction represents (part of) the non-enzymatic activity. Indeed, the in vitro reconstituted Fenton reaction removed OMPs > 50% better than the teas. From these data it is concluded that spent mushroom substrate of the white button mushroom, which is widely available as a waste-stream, can be used to purify water from OMPs.
Key points
•
A. bisporus SMS effectively removes OMPs from water, outperforming its tea.
•
A. bisporus SMS utilizes enzymatic and non-enzymatic activities for OMP removal.
•
A. bisporus SMS is a promising bioremediation substrate for OMP removal.
The robustness of reverse osmosis (RO) against polar organic micropollutants (MPs) was investigated in pilot-scale drinking water treatment. Experiments were carried in hypoxic conditions to treat a ...raw anaerobic riverbank filtrate spiked with a mixture of thirty model compounds. The chemicals were selected from scientific literature data based on their relevance for the quality of freshwater systems, RO permeate and drinking water. MPs passage and the influence of permeate flux were evaluated with a typical low-pressure RO membrane and quantified by liquid chromatography coupled to high-resolution mass spectrometry. A strong inverse correlation between size and passage of neutral hydrophilic compounds was observed. This correlation was weaker for moderately hydrophobic MPs. Anionic MPs displayed nearly no passage due to electrostatic repulsion with the negatively charged membrane surface, whereas breakthrough of small cationic MPs could be observed. The passage figures observed for the investigated set of MPs ranged from less than 1%–25%. Statistical analysis was performed to evaluate the relationship between physicochemical properties and passage. The effects of permeate flux were more pronounced for small neutral MPs, which displayed a higher passage after a pressure drop.
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•Strong size-passage correlation for neutral hydrophilic organics (logD<2).•Weaker size-passage correlation for moderately hydrophobic organics (logD>2).•Passage of cationic organics was higher than that of anions of comparable size.•Low permeate flux resulted in increased passage of small neutral polar organics.•Higher salt and organic passage observed for at least 5 h following a pressure drop.
The excessive use and accumulation of water-soluble polymers (WSPs, known as “liquid plastics”) in the environment can pose potential risks to both ecosystems and human health, but the environmental ...fate of WSPs remains unclear. Here, the adsorption behavior of WSPs with different molecular weight on kaolinite (Kaol) and montmorillonite (Mt) were examined. The results showed that the adsorption of PEG and PVP on minerals were controlled by hydrogen bond and van der Waals force. The Fourier transform infrared (FTIR) spectra and two-dimensional correlation spectroscopy (2D-COS) analysis revealed that there were interactions between the Al-O and Si-O groups of the minerals and the polar O- or N-containing functional groups as well as the alkyl groups of PEG and PVP. The adsorption characteristics of WSPs were closely related to their molecular weight and the pore size of minerals. Due to the relatively large mesopore size of Kaol, both PEG and PVP were absorbed into inner spaces, for which the adsorption capacity increased with molecular weight of the polymers. For Mt, all types of PEG could enter its micropores, while PVP with larger molecular weights appeared to be confined externally, leading to a decrease in the adsorption capacity of PVP with increasing molecular weight. The findings of this study provide a theoretical basis for scientific evaluation of environmental processes of WSPs.
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•WSPs (PEG and PVP) adsorption on kaolin and montmorillonite minerals was assessed.•Hydrogen bond and van der Waals force dominated the adsorption of WSPs.•The adsorption of WSPs depended on their molecular weight and mineral pore size.•PEG of all molecular weights (<10 kDa) could penetrate the internal spaces of both minerals.•High molecular weight PVP was restricted to the external surface of montmorillonite.
Biofilm formation, loose deposit accumulation and water quality deterioration in drinking water distribution systems have been widely reported. However, the accumulation and distribution of harbored ...elements and microbes in the different niches (loose deposits, PVC-U biofilm, and HDPE biofilm) and their corresponding potential contribution to water quality deterioration remain unknown. This precludes an in-depth understanding of water quality deterioration and the development of proactive management strategies. The present study quantitatively evaluated the distribution of elements, ATP, Aeromonas spp., and bacterial communities in distribution pipes (PVC-U, D = 110 mm, loose deposit and biofilm niches) and household connection pipes (HDPE, D = 32 mm, HDPE biofilm niches) at ten locations in an unchlorinated distribution system. The results show that loose deposits in PVC-U pipes, acting as sinks, constitute a hotspot (highest total amount per meter pipe) for elements, ATP, and target bacteria groups (e.g., Aeromonas spp., Mycobacterium spp., and Legionella spp.). When drinking water distribution system niches with harbored elements and microbes become sources in the event of disturbances, the highest quality deterioration potential (QDP) is that of HDPE biofilm; this can be attributed to its high surface-to-volume ratio. 16s rRNA analysis demonstrates that, at the genus level, the bacterial communities in the water, loose deposits, PVC-U biofilm, and HDPE biofilm were dominated, respectively, by Polaromonas spp. (2–23%), Nitrosipra spp. (1–47%), Flavobacterium spp. (1–36%), and Flavobacterium spp. (5–67%). The combined results of elemental composition and bacterial community analyses indicate that different dominant bio-chemical processes might occur within the different niches—for example, iron-arsenic oxidizing in loose deposits, bio-calumniation in PVC-U biofilm, and methane oxidizing in HDPE biofilm. The release of 20% loose deposits, 20% PVC-U biofilm and 10% HDPE biofilm will cause significant changes of water bacterial community.
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•Concepts of hotspot and quality deterioration potential were proposed and evaluated.•Aeromonas spp. accumulated only in the niche of loose deposits.•Loose deposits are hotspots for Fe, Mn, As, Al, and microbes.•HDPE pipes have the highest water-quality deterioration potential for Fe, Mn, As, Al, and ATP.•Loose deposits and biofilm release may cause significant changes in water microbial community.
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•SMS of Agaricus bisporus and its aqueous extract remove textile dyes from water.•Non-water-extractable SMS compounds facilitate optimal removal of textile dyes.•Enzymatic and ...non-enzymatic activities in SMS remove textile dyes.
The textile industry discharges up to 5 % of their dyes in aqueous effluents. Here, use of spent mushroom substrate (SMS) of commercial white button mushroom production and its aqueous extract, SMS tea, was assessed to remove textile dyes from water. A total of 30–90 % and 5–85 % of the dyes was removed after a 24 h incubation in SMS and SMS tea, respectively. Removal of malachite green and remazol brilliant blue R was similar in SMS and its tea. In contrast, removal of crystal violet, orange G, and rose bengal was higher in SMS, explained by sorption to SMS and by the role of non-water-extractable SMS components in discoloration. Heat-treating SMS and its tea, thereby inactivating enzymes, reduced dye removal to 8–58 % and 0–31 %, respectively, indicating that dyes are removed by both enzymatic and non-enzymatic activities. Together, SMS of white button mushroom production has high potential to treat textile-dye-polluted aqueous effluents.
Efficient recovery of ammonium, a valuable nutrient, from dilute streams is still an unsolved challenge. One possible approach to separate and simultaneously concentrate ammonium from low ...concentration streams is Donnan dialysis. To design a process, a mass transport model was utilized for both plate and frame and hollow fiber modules and compared to experiments. The chosen model was based on film theory, accounting for mass transport resistances in the liquid as well as the membrane phase to allow for a complete investigation of mass transfer limitations. Experimental data for the flux of ammonium and potassium using flat sheet Nafion-115 and FujiFilm type-2 and hollow fiber Nafion membranes was predicted very well by the model for several flow conditions and concentrations. The two stage ammonium removal could be predicted accurately from a starting concentration over two orders of magnitude in concentration. For the hollow fiber module case, liquid phase resistances on the draw side were more substantial vs. plate and frame due to the lower velocity. Both plate and frame and hollow fiber modules showed similar transport rates, up to 1mol/(m2·h). In the investigated, non-optimized, laboratory system, an 80% removal of ammonium was achieved with a processing flow of 12.5 L/(m2·h).
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•Simple robust mass transfer model of Donnan dialysis for liquid and membrane phases.•Mass transfer limitations shift from liquid to membrane phase.•Analytical model accurately predicts hollow fiber and flat sheet membrane systems.•Two stage Donnan dialysis showed 98.5% ammonium removal and concentration to 30 mM.•It allowed for a treatment rate of 12.5 L/(m2·h) and ionic fluxes of ∼1 mol/(m2·h).
Antiscalants are well known to prevent the precipitation of carbonate and sulphate scales of calcium in reverse osmosis (RO) applications, but according to literature their inhibitory ability against ...calcium phosphate is not clear. The objective of this study was to investigate if antiscalants, without acid addition, can prevent calcium phosphate scaling in RO systems. Eight calcium phosphate antiscalants from different manufacturers spanning a range of concentrations were tested in batch (in glass reactors) experiments to inhibit the formation of calcium phosphate in synthetic concentrate corresponding to 85% recovery (Ca2+ = 765 mg/L, PO43− = 13–15 mg/L and pH = 7.6) of a groundwater RO in the Netherlands. Additionally, once-through lab-scale RO tests were conducted where an RO element was fed with synthetic concentrate and the performance of antiscalants was evaluated from the rate of flux-decline in the RO element. Without antiscalant addition, a substantial flux-decline was observed due to the deposition of amorphous calcium phosphate (ACP) on the RO membrane. The tested antiscalants were unable to inhibit the formation of ACP and were incapable of preventing the deposition of the formed ACP particles, since with each antiscalant, the flux of the RO element decreased at least 15% in a 3-h period. Briefly, the available antiscalants, tested in this study, did not provide acceptable inhibition of calcium phosphate scaling in RO applications.
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•Crystalline phases of calcium phosphate were not responsible for flux decline in RO.•Flux decline was caused by the deposition of ACP particles on the RO membrane.•Antiscalants were unable to prevent the formation and the deposition of ACP in RO.•Antiscalants were able to hinder the agglomeration of the formed ACP particles.
An improved flux-step method is presented incorporating cleaning steps by relaxation to determine the critical flux and the critical flux for irreversibility. Experiments are performed with activated ...sludge fed with real municipal wastewater. The improved flux-step method is compared with a common flux-step method often used in the literature. The critical flux for a polyvinylidenefluoride flat-sheet membrane with a pore size of 0.1
μm is 56
±
2
L
m
−2
h
−1 according to the common flux-step method and 52
±
3
L
m
−2
h
−1 according to the improved flux-step method. The marginal difference is explained by the application of larger flux-steps in the improved flux-step method. By applying intermediate relaxation the fouling appears to be almost completely reversible, indicating that cake layer formation is the dominant fouling mechanism. The cake layer remains removable up to a flux of 100
L
m
−2
h
−1. The critical flux for irreversibility is therefore larger than 100
L
m
−2
h
−1.
The influence of fouling history is reduced by intermediate relaxation. As a result, the total fouling rate is much lower with the improved flux-step method compared to the common flux-step method, showing almost no fouling rate hysteresis in the improved method.
A low amount of irreversible fouling is measured due to the adsorption of macromolecules, pore blocking, and/or gel formation. Applying the improved method ten times consecutively shows the influence of irreversible fouling on the long term. The critical flux decreases by 4
L
m
−2
h
−1 as a consequence of irreversible fouling during the ten runs representing a long filtration run of 150
h at a net flux of 19
L
m
−2
h
−1.
The potential of membrane scaling control by a real-time optimization algorithm was investigated. The effect of antiscalant dosing was evaluated from the induction time measured in glass ...batch-reactors, and from the operational performance of a lab-scale reverse osmosis (RO) unit and two pilot-scale RO units. Step changes in the antiscalant dosing demonstrated that the accumulation of scaling is ‘paused’ during periods when the optimum dose is applied. This is paramount for the application of a dynamic dosing strategy that may briefly underdose, while searching for the optimum dose. It was found that antiscalant underdose and overdose were both detrimental to RO operation since underdose resulted in membrane scaling, while overdose led to membrane fouling due to calcium-antiscalant deposits. The dosing algorithm was used to minimize antiscalant consumption in two pilot RO units. The algorithm was able to lower the antiscalant doses to 0.2 mg/L and 0.6 mg/L, while the supplier's recommended antiscalant doses were 2.0 mg/L and 4.5 mg/L, respectively. As a result, the algorithm could reduce antiscalant consumption by up to 85–90% for the plants mentioned.
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•Antiscalant underdose and overdose can lead to flux decline in RO.•Antiscalants can inhibit further scaling in RO where membranes were already scaled.•The dosing algorithm determines the optimum antiscalant dose to control scaling.•Optimization reduced the antiscalant dose by 85–90% in two RO pilot units.
Driven by the development of water purification technologies and water quality regulations, the use of better source water and/or upgraded water treatment processes to improve drinking water quality ...have become common practices worldwide. However, even though these elements lead to improved water quality, the water quality may be impacted during its distribution through piped networks due to the processes such as pipe material release, biofilm formation and detachment, accumulation and resuspension of loose deposits. Irregular changes in supply-water quality may cause physiochemical and microbiological de-stabilization of pipe material, biofilms and loose deposits in the distribution system that have been established over decades and may harbor components that cause health or esthetical issues (brown water). Even though it is clearly relevant to customers' health (e.g., recent Flint water crisis), until now, switching of supply-water quality is done without any systematic evaluation. This article reviews the contaminants that develop in the water distribution system and their characteristics, as well as the possible transition effects during the switching of treated water quality by destabilization and the release of pipe material and contaminants into the water and the subsequent risks. At the end of this article, a framework is proposed for the evaluation of potential transition effects.
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•Loose deposits, biofilm matrix and pipe scales developed and stabilized over decades in DNs.•Irregular changes of water quality may cause destabilization of pipe material and contaminants.•The potential transition effects can lead to health or esthetic issues (e.g., Flint water crisis).•A framework for systematic transition effects evaluation is proposed.
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