Tag Archives: water treatment

Oxidatively Modified Carbon (OMC) Removes Radioactive Elements

Artur Khannanov, Vadim V. Nekljudov, Airat Kiiamov, Ayrat M. Dimiev. Oxidatively modified carbon as efficient material for removing radionuclides from water. Carbon, Volume 115, May 2017, Pages 394–401http://dx.doi.org/10.1016/j.carbon.2017.01.025

There is a constant need to develop advantageous materials for removing radioactive waste from aqueous systems. Here we propose a new carbon-based material prepared by oxidative treatment of various natural carbon sources. The as-prepared oxidatively modified carbon (OMC) has an oxygen-rich surface, and retains its particulate granular texture. It has relatively low cost and can be used in traditional filtration columns. The sorption ability of OMC toward several metal cations is demonstrated. It is especially efficient toward Cs+ cations, the species that are among the most difficult to remove from the waters at the Fukushima nuclear plant. 

Polyvoxometalate Supported Ionic Liquid Phases (POM-SLIPS) Removes Contaminants from Water

Dr. Sven Herrmann, Dr. Laura De Matteis, Dr. Jesús M. de la Fuente, Dr. Scott G. Mitchell, Prof. Dr. Carsten Streb. Removal of Multiple Contaminants from Water by Polyoxometalate Supported Ionic Liquid Phases (POM-SILPs) Angewandte Chemie Volume 56, Issue 6 February 1, 2017 Pages 1667–1670

The simultaneous removal of organic, inorganic, and microbial contaminants from water by one material offers significant advantages when fast, facile, and robust water purification is required. Herein, we present a supported ionic liquid phase (SILP) composite where each component targets a specific type of water contaminant: a polyoxometalate-ionic liquid (POM-IL) is immobilized on porous silica, giving the heterogeneous SILP. The water-insoluble POM-IL is composed of antimicrobial alkylammonium cations and lacunary polyoxometalate anions with heavy-metal binding sites. The lipophilicity of the POM-IL enables adsorption of organic contaminants. The silica support can bind radionuclides. Using the POM-SILP in filtration columns enables one-step multi-contaminant water purification. The results show how multi-functional POM-SILPs can be designed for advanced purification applications.

Ozone regeneration of GAC to control THMs

He X, Elkouz M, Inyang M, Dickenson E, Wert EC. Ozone regeneration of granular activated carbon for trihalomethane control. Journal of hazardous materials 2016 Dec 9;326:101-109. doi: 10.1016/j.jhazmat.2016.12.016.

Spatial and temporal variations of trihalomethanes (THMs) in distribution systems have challenged water treatment facilities to comply with disinfection byproduct rules. In this study, granular activated carbon (GAC) and modified GAC (i.e., Ag-GAC and TiO2-GAC) were used to treat chlorinated tap water containing CHCl3 (15-21μg/L), CHBrCl2 (13-16μg/L), CHBr2Cl (13-14μg/L), and CHBr3 (3μg/L). Following breakthrough of dissolved organic carbon (DOC), GAC were regenerated using conventional and novel methods. GAC regeneration efficiency was assessed by measuring adsorptive (DOC, UV absorbance at 254nm, and THMs) and physical (surface area and pore volume) properties. Thermal regeneration resulted in a brief period of additional DOC adsorption (bed volume, BV, ∼6000), while ozone regeneration was ineffective regardless of the GAC type. THM adsorption was restored by either method (e.g., BV for ≥80% breakthrough, CHBr3 ∼44,000>CHBr2Cl ∼35,000>CHBrCl2 ∼31,000>CHCl3 ∼7000). Cellular and attached adenosine triphosphate measurements illustrated the antimicrobial effects of Ag-GAC, which may have allowed for the extended THM adsorption compared to the other GAC types. The results illustrate that ozone regeneration may be a viable in-situ alternative for the adsorption of THMs during localized treatment in drinking water distribution systems.

Mineralization of 2,6-Dichlorobenzamide in Sand Filters

Vandermaesen J, Horemans B, Degryse J, Boonen J, Walravens E, Springael D. Mineralization of the common groundwater pollutant 2,6-dichlorobenzamide (BAM) and its metabolite 2,6-dichlorobenzoic acid (2,6-DCBA) in sand filter units of drinking water treatment plants. Environmental Science and Technology. 2016 Aug 17.

The intrinsic capacity to mineralize the groundwater pollutant 2,6-dichlorobenzamide (BAM) and its metabolite 2,6-dichlorobenzoic acid (2,6-DCBA) was evaluated in samples from sand filters (SFs) of drinking water treatment plants (DWTPs). Whereas BAM mineralization occurred rarely and only in SFs exposed to BAM, 2,6-DCBA mineralization was common in SFs, including those treating uncontaminated water. Nevertheless, SFs treating BAM contaminated water showed the highest 2,6-DCBA mineralization rates. For comparison, 2,6-DCBA and BAM mineralization were determined in various topsoil samples. As in SF samples, BAM mineralization was rare, whereas 2,6-DCBA mineralization capacity appeared widespread, with high mineralization rates found especially in forest soils. Multivariate analysis showed that in both SF and soil samples, high 2,6-DCBA mineralization correlated with high organic carbon content. Adding a 2,6-DCBA degradation deficient mutant of the BAM mineralizing Aminobacter sp. MSH1 confirmed that 2,6-DCBA produced from BAM is rapidly mineralized by the endogenous microbial community in SFs showing intrinsic 2,6-DCBA mineralization. This study demonstrates that (i) 2,6-DCBA mineralization is widely established in SFs of DWTPs, allowing the mineralization of any 2,6-DCBA produced during BAM degradation and (ii) the first metabolic step in BAM mineralization is rare in microbial communities, rather than its further degradation beyond 2,6-DCBA.

Removal of Sulfonamides from Drinking Water

Cui C, Jin L, Jiang L, Han Q, Lin K, Lu S, Zhang D, Cao G.
Removal of trace level amounts of twelve sulfonamides from drinking water by UV-activated peroxymonosulfate. The Science of the total environment. 2016 Aug 5;572:244-251. doi: 10.1016/j.scitotenv.2016.07.183.

Trace levels of residual antibiotics in drinking water may threaten public health and become a serious problem in modern society. In this work, we investigated the degradation of twelve sulfonamides (SAs) at environmentally relevant trace level concentrations by three different methods: ultraviolet (UV) photolysis, peroxymonosulfate (PMS) oxidation, and UV-activated PMS (UV/PMS). Sulfaguanidine, sulfadiazine, sulfamerazine, sulfamethazine, sulfathiazole, sulfamethoxydiazine, and sulfadimethoxine were be effectively removed by direct UV photolysis and PMS oxidation. However, sulfanilamide, sulfamethizole, sulfamethoxazole, sulfisoxazole, and sulfachloropyridazine were not completely degraded, despite prolonging the UV irradiation time to 30min or increasing the PMS concentration to 5.0mg·L-1. UV/PMS provided more thorough elimination of SAs, as demonstrated by the complete removal of 200 ng·L-1 of all SAs within 5min at an initial PMS concentration of 1.0mg·L-1. UV/PMS promoted SA decomposition more efficiently than UV photolysis or PMS oxidation alone. Bicarbonate concentration and pH had a negligible effect on SA degradation by UV/PMS. However, humic acid retarded the process. Removal of 200 ng·L-1 of each SA from a sample of sand-filtered effluent from a drinking water treatment plant (DWTPs) was quickly and completely achieved by UV/PMS. Meanwhile, about 41% of the total organic carbon (TOC) was eliminated. Scavenging experiments showed that sulfate radical (SO4) was the predominant species involved in the degradation. It is concluded that UV/PMS is a rapid and efficient method for removing trace-level SAs from drinking water.

Lime Softening Effective for Strontium Removal

O’Donnell AJ, Lytle DA, Harmon S, Vu K, Chait H, Dionysiou DD. Removal of strontium from drinking water by conventional treatment and lime softening in bench-scale studies. Water Research. 2016 Jun 21;103:319-333. doi: 10.1016/j.watres.2016.06.036.

The United States Environmental Protection Agency Contaminant Candidate List 3 lists strontium as a contaminant for potential regulatory consideration in drinking water. Very limited data is available on strontium removal from drinking water and as a result, there is an immediate need for treatment information. The objective of this work is to evaluate the effectiveness of coagulation/filtration and lime-soda ash softening treatment methods to remove strontium from surface and ground waters. Coagulation/filtration jar test results on natural waters showed that conventional treatment with aluminum and iron coagulants were able to achieve only 12% and 5.9% strontium removal, while lime softening removed as high as 78% from natural strontium-containing ground water. Controlled batch experiments on synthetic water showed that strontium removal during the lime-soda ash softening was affected by pH, calcium concentration and dissolved inorganic carbon concentration. In all softening jar tests, the final strontium concentration was directly related to the initial strontium concentration and the removal of strontium was directly associated with calcium removal. Precipitated solids showed well-formed crystals or agglomerates of mixed solids, two polymorphs of calcium carbonate (vaterite and calcite), and strontianite, depending on initial water quality conditions. X-ray diffraction analysis suggested that strontium was likely incorporated in the calcium carbonate crystal lattice and was likely responsible for removal during lime softening.

Life Cycle Assessment-Based Optimization of Drinking Water Treatment

Capitanescu F, Rege S, Marvuglia A, Benetto E, Ahmadi A, Gutiérrez TN, Tiruta-Barna L. Cost versus life cycle assessment-based environmental impact optimization of drinking water production plants. Journal of environmental management 2016 Apr 21;177:278-287. doi: 10.1016/j.jenvman.2016.04.027.

Empowering decision makers with cost-effective solutions for reducing industrial processes environmental burden, at both design and operation stages, is nowadays a major worldwide concern. The paper addresses this issue for the sector of drinking water production plants (DWPPs), seeking for optimal solutions trading-off operation cost and life cycle assessment (LCA)-based environmental impact while satisfying outlet water quality criteria. This leads to a challenging bi-objective constrained optimization problem, which relies on a computationally expensive intricate process-modelling simulator of the DWPP and has to be solved with limited computational budget. Since mathematical programming methods are unusable in this case, the paper examines the performances in tackling these challenges of six off-the-shelf state-of-the-art global meta-heuristic optimization algorithms, suitable for such simulation-based optimization, namely Strength Pareto Evolutionary Algorithm (SPEA2), Non-dominated Sorting Genetic Algorithm (NSGA-II), Indicator-based Evolutionary Algorithm (IBEA), Multi-Objective Evolutionary Algorithm based on Decomposition (MOEA/D), Differential Evolution (DE), and Particle Swarm Optimization (PSO). The results of optimization reveal that good reduction in both operating cost and environmental impact of the DWPP can be obtained. Furthermore, NSGA-II outperforms the other competing algorithms while MOEA/D and DE perform unexpectedly poorly.