Pilot-scale Tests Research Articles

Aplicación industrial de levaduras nativas para la producción de cervezas artesanales

Two native wine Saccharomyces cerevisiae strains (Sc 00/30 and Sc 00/35), previously selected at brewing laboratory scale, for their fermentative capacity, ß-glycosidase activity, and good sensory characteristics in brewing musts, were applied and characterized for industrial brewing. Belgian Specialty Ale style beers were brewed at a craft brewery. Inoculations were carried out on malted barley musts in 225-litre oak barrels. The physicochemical and sensory data obtained are within the expected ranges for beers of this style, with the Sc 00/30 strain standing out for its lower volatile acidity value and improved sensory complexity, with a greater diversity of fruity notes, mainly apple and pear. The sensory descriptors found make them interesting strains for the production of Belgian style beers (Belgian Golden Strong Ale), wheat beers (German Wheat Beer, Weissbier), smoked beers (Rachbier) and fruit beers. The pilot scale tests reproduced the results obtained in the laboratory, so that the use of wine native Saccharomyces cerevisiae strains provide a brewing differentiation factor which decreases the standardization of flavours and aromas produced by commercial yeasts, making possible the obtention of beers with a Uruguayan identity in the future.

바이오매스 부산물에 상용화제를 첨가하여 제조한 멀칭필름의 분해 실태 연구

Mulching film was produced by LDPE and LLDPE adding biomass byproducts and MA(maleic anhydride), talc/clay/CaO/CaCO3. And also surveyed to tensile strength, elongation, TGA and DSC according to the UV irradiation time. The tensile strength and elongation showed 20 N/cm2 and 5% after UV irradiation 100 hours, and those was nearly 0 N/cm2 and 0% after 200 hours, respectively. TGA of film was showed to peak of polymer itself, and DSC was slightly higher than that of initial value. At the pilot scale test, we were able to see the differentiate of degradation between control and developed film after 12 weeks, and also torn off at several part of mulching film. The degradation of mulching film after growing corn showed similar to a pilot scale test. Above the results, the developed mulching film adding biomass will be to used for agricultural farming.

Biochar-seeded struvite precipitation for simultaneous nutrient recovery and chemical oxygen demand removal in leachate: From laboratory to pilot scale.

Refuse transfer station (RTS) leachate treatment call for efficient methods to increase nutrient recovery (NH4 +−N and PO4 3−−P) and chemical oxygen demand (COD) removal. In this study, the effects of various operational factors (seeding dose, pH, initial NH4 +-N concentration, and reaction time) on biochar-seeded struvite precipitation were investigated at laboratory and pilot scales. Mealworm frass biochar (MFB) and corn stover biochar (CSB) were used as seeding materials to compare with traditional seed struvite. The maximum NH4 +−N and PO4 3−−P recover efficiency of the MFB-seeded process reached 85.4 and 97.5%, higher than non-seeded (78.5 and 88.0%) and CSB-seeded (80.5 and 92.0%) processes and close to the struvite-seeded (84.5 and 95.1%) process. The MFB-seeded process also exhibited higher COD removal capacity (46.4%) compared to CSB-seeded (35.9%) and struvite-seeded (31.2%) processes and increased the average particle size of the struvite product from 33.7 to 70.2 μm for better sustained release. XRD, FT-IR, and SEM confirmed the orthorhombic crystal structure with organic matter attached to the struvite product. A pilot-scale test was further carried out in a custom-designed stirred tank reactor (20 L). In the pilot-scale test, the MFB-seeded process still spectacularly recovered 77.9% of NH4 +−N and 96.1% of PO4 3−−P with 42.1% COD removal, which was slightly lower than the laboratory test due to insufficient and uniform agitation. On the whole, MFB-seeded struvite precipitation is considered to be a promising pretreatment method for rural RTS leachate.

Efficient Utilization of Siderite- and Hematite-Mixed Ore by Suspension Magnetization Roasting: A Pilot-Scale Study

Steel is an important industrial raw material and plays an important role in industrial construction. Studying the efficient utilization of complex refractory iron ore with large reserves is of great significance to ensure the strategic safety of China’s iron and steel industry. Focusing on the typical mixed iron ore of siderite (FeCO3) and hematite (Fe2O3), this paper analyzes the possible ways of magnetization roasting from the perspective of thermodynamics and highlights that oxidation–reduction roasting is an easy way to realize industrial application. On this basis, a pilot-scale test of suspension magnetization roasting followed by low-intensity magnetic separation is carried out by using a newly developed suspension magnetization roasting furnace. The effects of roasting temperature, CO consumption, and N2 consumption on the magnetization roasting process are investigated, and 24 h continuous tests are carried out. Here, we find continuous suspension magnetization roasting followed by low-intensity magnetic separation can obtain a total iron grade of over 56% with an average value of 57.18% and a total iron recovery rate of over 91% with an average value of 92.22%. Product analysis shows that after SMR, iron minerals such as siderite and hematite transform into magnetite, with a substantial increase in magnetism, which is conducive to the separation of iron ore. The results provide a reference for the development and utilization of siderite- and hematite-mixed iron ore.

A Review on Enhancing Cupriavidus necator Fermentation for Poly(3-hydroxybutyrate) (PHB) Production From Low-Cost Carbon Sources

In the context of a circular economy, bioplastic production using biodegradable materials such as poly(3-hydroxybutyrate) (PHB) has been proposed as a promising solution to fundamentally solve the disposal issue of plastic waste. PHB production techniques through fermentation of PHB-accumulating microbes such as Cupriavidus necator have been revolutionized over the past several years with the development of new strategies such as metabolic engineering. This review comprehensively summarizes the latest PHB production technologies via Cupriavidus necator fermentation. The mechanism of the biosynthesis pathway for PHB production was first assessed. PHB production efficiencies of common carbon sources, including food waste, lignocellulosic materials, glycerol, and carbon dioxide, were then summarized and critically analyzed. The key findings in enhancing strategies for PHB production in recent years, including pre-treatment methods, nutrient limitations, feeding optimization strategies, and metabolism engineering strategies, were summarized. Furthermore, technical challenges and future prospects of strategies for enhanced production efficiencies of PHB were also highlighted. Based on the overview of the current enhancing technologies, more pilot-scale and larger-scale tests are essential for future implementation of enhancing strategies in full-scale biogas plants. Critical analyses of various enhancing strategies would facilitate the establishment of more sustainable microbial fermentation systems for better waste management and greater efficiency of PHB production.

Integration of sludge ozonation with anaerobic digestion: From batch testing to scenario analysis with energy, economic and environmental assessment

A methodological procedure, based on results from batch experiments, is proposed and applied to a selected wastewater treatment plant generating a poorly degradable sludge, to identify the best configuration and ozone dosage for full-scale application of sludge ozonation. Samples of pre-thickened and digested sludge were collected, tested at different ozone dosages and characterized to gather useful data for energy, economic and carbon footprint balances. The most viable scenario was found to be sludge pre-treatment at the lowest tested dosage (20 mg O3/g VS), yielding energy, cost and GHG emission net savings of 177 MWh/y, 57.8 k€/y and 6.38 Mg CO2-eq./y, respectively. Sensitivity analyses, conducted by varying the specific energy required for ozone generation and the unit costs for sludge disposal and resource supply, confirmed the stability of this scenario, whereas a field pilot-scale testing is advisable to verify modified process conditions for a safe and efficient application of sludge ozonation. The proposed methodology, including laboratory batch anaerobic digestion tests, scenario definition and energy/economic/environmental balances, could be preliminary applicable to all situations to broadly analyze all involved aspects and give a useful overview about the effective applicability of sludge ozonation.

Determination of alpha factors for monitoring of aeration systems with the ex situ off-gas method: experience from practical application and estimation of measurement uncertainty

Performance of aeration systems in wastewater treatment plants (WWTP) under process conditions can be monitored with off-gas tests. The ex situ off-gas method transfers activated sludge from an adjacent aeration tank into aerated columns to determine oxygen transfer parameters (e.g., the α-factor). This method is an alternative to in situ off-gas testing with hoods at the tank surface; however, its application and measurement uncertainty have not been examined yet. We outline our experience from long-term off-gas testing with two pilot-scale test reactors (8.3 m3 volume). Global variance-based sensitivity analysis using Sobol’ indices revealed oxygen concentration in off-gas and dissolved oxygen as the most important input quantities to determine α-factors accurately. Measurement uncertainty of other instruments was negligible. These findings are transferable to in situ off-gas hoods because the methods are similar. Random measurement error of α-factors was estimated with uncertainty analysis and comparison measurements to a relative standard deviation of about ± 2.8% for our ex situ pilot setup. Diffuser fouling, biofilm growth, or sensor drift caused systematic errors avoidable by maintenance. Additional mixing of bubble column due to sludge inflow into ex situ tanks led to a systematic overestimation of α-factors at lower airflow rates. Hence, the ex situ off-gas method is not suitable to determine α-factors for the design of aeration systems but offers unique possibilities for research of oxygen transfer dynamics and development of aeration equipment because ex situ columns can be operated independently from a full-scale activated sludge tank.

Application of Pulsed Electric Fields to Pilot and Industrial Scale Virgin Olive Oil Extraction: Impact on Organoleptic and Functional Quality.

The quality of virgin olive oil (VOO) is largely determined by the technology used in the industrial process of extracting the oil. Technological innovations within this field aim to strike a proper balance between oil yield and the optimal chemical composition of VOO. The application of pulsed electric fields (PEF) that cause the electroporation of the plant cell membranes favors a more efficient breakage of the olive fruit tissue, which in turn could facilitate the extraction of the oil and some of its key minor components. Pilot-scale and industrial extraction tests have been conducted to assess the effect of PEF technology on the oil extraction yield and on the organoleptic and functional quality of VOO. The best results were obtained by combining the PEF treatment (2 kV/cm) with short malaxation times and a low processing temperature. Under these conditions, PEF technology could decisively improve the oil yield by up to 25% under optimal conditions and enhance the incorporation of phenolic and volatile compounds into the oils. The PEF treatment neither affected the physicochemical parameters used to determine the commercial categories of olive oils, nor the tocopherol content. Similarly, the sensory evaluation of the PEF-extracted oils by means of a panel test did not detect the appearance of any defect or off-flavor. In addition, the intensity of positive attributes (fruity, bitter and pungent) was generally higher in PEF oils than in control oils.

Novel rapid cooling system design and modeling for continuous flow food processing systems

The commercial sterility in thermal processing is achieved by implementation of high temperatures that often has a negative impact on the heat sensitive health promoting nutrients like vitamins, antioxidants, flavors, and phytochemicals. Although tremendous progress has been made in rapid heating with the advancements in volumetric heating technologies like ohmic and microwave heating, the advancement in rapid cooling remains unexplored to further minimize the product quality degradation. A novel rapid cooling heat exchanger design modification was made to the traditional cooling system to improve the rate of cooling by direct injection of cooling gas media. Pilot-scale tests were conducted on a model food with an Ultra High Temperature (UHT) processing unit and an add-on novel cooling design. The cooling rate achieved by the rapid cooling design was found to be 7.5 ± 0.01 °C/s, which was 15 times the cooling rate provided by the traditional UHT cooling system. Mathematical models were developed to predict the time-temperature profile and the nutrient retention based on the new design. The model simulations for the new cooling design showed additional retention of 14.81% antioxidant content, 4.13% anthocyanins, 14.43% total flavonoid content as compared to the traditional cooling system.

Copper and zinc extraction from underspoil waters using sulfur solution in sodium hydroxide

During the passage of atmospheric precipitates through the porous dump body, the products of oxidation of sulfide minerals are dissolved. As a result, underspoil waters with low pH values and a significant amount of dissolved metals are formed. For the most part, all types of the sewage produced by mining and processing enterprises (underspoil, colliery, pit, drainage) are combined before treatment, which leads to the formation of a common water yield with complex chemical composition. According to the existing practice, the combined flow is neutralized with lime milk, which leads to irretrievable losses of non-ferrous metals with mud after neutralization. The use of the sulfiding method as part of the tactics of locally autonomous processing makes it possible to obtain the copper and zinc commercial products suitable for further metallurgical processing. Previously, sulphides of biogenic or chemical nature, as well as hydrogen sulphide, have been used in extraction of metals in the form of sulphides. In this study, we have used sulfur solution in sodium hydroxide with a mass ratio of NaOH:S = 1:1 as an alternative to the old reagents. During the study, the sulfur consumption for copper and zinc extraction were determined. The impact of water pH on zinc extraction is shown. The pilot-scale tests have confirmed the results of laboratory studies. Proposed is a flow chart with the following main operations: copper extraction, zinc extraction and the zinc product conditioning. Copper concentrate with a copper content of 32.9% and zinc concentrate with a zinc content of 48% were obtained. In the resulting deposits, copper is in the form of covellite (CuS), and zinc is in the form of sphalerite (ZnS). Through metal extraction was 99.9% for copper and 99.5% for zinc.

In Situ Remediation of Arsenic-Contaminated Groundwater by Injecting an Iron Oxide Nanoparticle-Based Adsorption Barrier

Arsenic contamination of groundwater occurs due to both geogenic and anthropogenic processes. Conventional arsenic remediation techniques require extraction of groundwater into pump-and-treat systems, which are expensive and require long operational times. Hence, there is a need for cost-effective remediation. In this study, we assessed and validated the in situ remediation of arsenic contamination in groundwater resources using permeable reactive barriers (PRBs) made of injectable, colloidal iron oxide nanoparticles in the laboratory and in field-scale pilot tests. Sand-packed, flow-through column studies were used in order to assess the sorption behavior of the iron oxide nanoparticles using field materials (sand, groundwater) in the laboratory. The breakthrough curves were analyzed using a reactive transport model considering linear and nonlinear adsorption isotherms and were fitted best with a chemical nonequilibrium consideration. The results were used to design a pilot-scale field test. The injected 28 m3 of nanoparticles (ca. 280 kg dry weight of iron oxide) were successfully delivered to the aquifer via an injection well. No mobile iron was detected downstream, confirming that a stable in situ barrier was formed that did not move with the groundwater flow. Arsenic concentrations in groundwater were reduced to the aimed 50% of the background value, despite the relatively short contact time between arsenic and the iron oxide in the barrier, due to the high flow velocity of 1.21 m/day. We compared the results of the laboratory and field tests and concluded that the single-parameter models based on retardation factor and/or adsorption capacity fail to predict the longevity of the barrier and the evolution of arsenic breakthrough with time, most likely because they do not consider the chemical nonequilibrium effects. Therefore, we propose that upscaling the laboratory findings to field design must be carried out with care and be coupled with detailed reactive transport models.

Introduction and preliminary testing of a 5 m3/h hydrogen production facility by Iodine–Sulfur thermochemical process

The Iodine–Sulfur (IS) or Sulfur–Iodine (SI) thermochemical water-splitting cycle is considered as one of the most promising hydrogen production methods through thermal chemical cycle process with heat. This paper introduces the new built hydrogen production testing facility of IS process made by industrial structural material (IS-5m3 facility). The TC4, Hastelloy C276 and SiC materials were chosen in this pilot-scale testing facility for different modules. The new designed structure of Bunsen reactor, HI decomposer and H2SO4 decomposer are described particularly, and the corresponding individual tests are successfully executed to verify the function of each section. Based on testing, a preliminary continuous experimental run was carried out in September of 2021 for about 4 h with the hydrogen production capacity of 80 L/h. The problems such as slight corrosion, lower hydrogen gas yield and shorter operation time faced in this experiment will be modified in the near future. A longer time operation and higher H2 production rate test will be carried out soon.

Pilot-Scale Cultivation of the Snow Alga Chloromonas typhlos in a Photobioreactor.

The most studied and cultivated microalgae have a temperature optimum between 20 and 35°C. This temperature range hampers sustainable microalgae growth in countries with colder periods. To overcome this problem, psychrotolerant microalgae, such as the snow alga Chloromonas typhlos, can be cultivated during these colder periods. However, most of the research work has been carried out in the laboratory. The step between laboratory-scale and large-scale cultivation is difficult, making pilot-scale tests crucial to gather more information. Here, we presented a successful pilot-scale growth test of C. typhlos. Seven batch mode growth periods were compared during two longer growth tests in a photobioreactor of 350 L. We demonstrated the potential of this alga to be cultivated at colder ambient temperatures. The tests were performed during winter and springtime to compare ambient temperature and sunlight influences. The growth and CO2 usage were continuously monitored to calculate the productivity and CO2 fixation efficiency. A maximum dry weight of 1.082 g L−1 was achieved while a maximum growth rate and maximum daily volumetric and areal productivities of 0.105 d−1, 0.110 g L−1 d−1, and 2.746 g m−2 d−1, respectively, were measured. Future tests to optimize the cultivation of C. typhlos and production of astaxanthin, for example, will be crucial to explore the potential of biomass production of C. typhlos on a commercial scale.

Struvite crystallization by using active serpentine: An innovative application for the economical and efficient recovery of phosphorus from black water

Recovery of phosphorus from wastewater through struvite crystallization is one of the most attractive methods. However, the cost of chemical consumption makes this technology is unattractive to some extent. In this work, highly active serpentine was prepared by one-step mechanical activation and then used to recover phosphate as struvite from the black water containing 132.8 mg/L phosphorus and 3144 mg/L ammonia nitrogen. The results indicated that the prepared active serpentine can release magnesium ions and hydroxide ions simultaneously into an aqueous solution and is an ideal raw material for struvite crystallization. The factors for phosphorus recovery in this process mainly include mechanical activation intensity, serpentine dosage, and contact time. For the actual black water, a high recovery rate of phosphorus (>98%) is achieved by using active serpentine as the magnesium and alkali source for struvite precipitation. The recovery product was identified as struvite with a median particle size of 32.96 μm. It was confirmed that the mechanical activation damaged the crystal structure of the raw serpentine, improving the activity of Mg2+ and OH−. The undissolved Si-containing particles act as crystal seeds, accelerating the struvite crystallization process. Furthermore, a pilot-scale test was conducted with a rural public toilet in Xiong'an New District, Hebei Province. The results showed that an acceptable phosphorus recovery (98%) could be achieved using active serpentine. Additionally, it was demonstrated that the serpentine process to recover phosphate as struvite reduced the cost by 54.4% in compared with an ordinary chemical process. The active serpentine is a promising dual source of magnesium and alkali for the phosphorus recovery by the struvite method. It has a potential prospect for the large-scale application in phosphorus recovery and struvite fertilizer production.

Laboratory and pilot-scale studies of membrane distillation for desalination of produced water from Permian Basin

Substantial quantities of produced water generated during the extraction of oil and gas from unconventional reservoirs present significant environmental concern and increase the operating cost for this industry. Membrane Distillation (MD) can serve as a potential solution for beneficial reuse of produced water by generating high-quality permeate and reducing the volume of produced water requiring disposal. This study investigated treatment of produced water from Permian Basin in both laboratory and pilot-scale studies. Laboratory tests revealed the potential to successfully recover 50% of produced water although some increase in permeate conductivity was observed due to the passage of ammonia from the feed side. Initial pilot-scale test with filtration of raw produced water as the only pre-treatment step led to precipitation of SrSO4, NaCl, and Fe in the system once the solubility limits for these salts were exceeded. However, chemical pretreatment that included pH adjustment, aeration, and barite precipitation, allowed successful steady-state operation of the AGMD pilot system for 5 days where the produced water was concentrated from 127 g/L to 255 g/L (~50% water recovery) while recovering high quality permeate. Overall, greater than 99.7 % salt rejection was achieved with the average permeate flux of 1.86 LMH. Mass balance analysis suggested potential Ba and Ca precipitation in the system but there was no impact on AGMD performance and permeate quality during 5 days of continuous operation in the field.

Sustainable Alternatives for Tertiary Treatment of Pulp and Paper Wastewater

In this work, different alternatives to conventional tertiary treatment of pulp and paper (P&P) wastewater (WW), i.e., physicochemical coagulation-flocculation, were investigated to enhance the environmental and economic sustainability of industrial wastewater treatment. In particular, following a preliminary characterization of secondary effluents, cloth filtration and adsorption were studied, the former by pilot-scale tests, while the latter at laboratory scale. An economic analysis was finally accomplished to verify the full-scale applicability of the most promising technologies. Cloth filtration showed excellent total suspended solids (TSS) removal efficiency (mean 81% removal) but a very limited influence on chemical oxygen demand (COD) (mean 10% removal) due to the prevalence of soluble COD on particulate COD. Adsorption, instead, led to a good COD removal efficiency (50% abatement at powdered activated carbon—PAC—dosage of 400 mg/L). The economic analysis proved that adsorption would be convenient only if a local low-cost (100 €/ton) adsorbent supply chain was established. Ultrafiltration was considered as well as a potential alternative: its huge capital cost (19 M€) could be recovered in a relatively short timeframe (pay-back time of 4.7 years) if the ultrafiltrated effluent could be sold to local industries.

Oil Load Reduction of Oilfield-Produced Water by Applying Swirl–Cyclonic Flotation: A Pilot-Scale Investigation

A swirl–cyclonic flotation (SCF) apparatus was fabricated by combining hydrocyclone and air flotation separation to reduce the oil droplet load of oilfield-produced water. The apparatus was designed as three concentric cylinders with functions of swirling, air flotation separation, and oil collection. Influencing factors such as influent flow, oil concentration, and aeration rate were investigated in the pilot-scale test. The oil concentration of the effluent was below 100 mg/L during the continuous operation under an influent flow rate of 1.5 m3/h and an aeration rate of 0.4 L/min without addition of any chemicals. Results could be explained by the improvement in the floating velocity of oil droplets, resulting in oil load reduction. The oil and water separation mechanism of the SCF apparatus was determined by analysis of oil droplet size distribution. Compared with other flotation apparatus, the SCF apparatus had the advantages of high oil removal efficiency, low retention time, and stable water treatment quality. The apparatus also had no chemical agents added and had less floor area, leading to reduced chemical cost. The designed SCF apparatus has potential industrial application as pretreatment for oil–water load reduction.

A novel design of in-line static mixer for permanganate/bisulfite process: Numerical simulations and pilot-scale testing.

An increasing number of chemical technologies to wipe out contaminants within an incredibly short period of time have been developed recently, while their application was always hindered by the inefficient or improper mixing of reactants. To address this issue, the present work proposed a new static mixer named Tai-Chi which consists of blade, fin, and spoiler elements. Tai-Chi mixer can slice and divert the solutions inside and generate high shear flow to promote mixing process. Numerical simulations helped to determine the optimal operating conditions for Tai-Chi mixer, including laying its components anterior to the injection nozzles and keeping the velocity rate ratio of main pipe to branch pipe within the range of 0.5 to 1. Numerical simulations further proved that Tai-Chi mixer could strike a great balance between mixing performance (coefficient of variation [CoV] reaches 0.1 within 5 to 7 pipe diameters downstream) and head loss (nearly a half of other high shear static mixer in the market). Data of pilot-scale testing by Tai-Chi mixer confirm that 80% sulfamethoxazole could be eliminated in permanganate/bisulfite process within 8 pipe diameters, as well as showed the superiority of Tai-Chi's mixing performance in early stage compared with other static mixers in the market. PRACTITIONER POINTS: A Tai-Chi static mixer with blade, fin, and spoiler elements is devised. The optimal condition of flow rate and installment of Tai-Chi mixer is determined. Ultra-fast mixing is achieved by Tai-Chi (CoV < 0.1 within 5-7 pipe diameters). Pilot-scale test verifies the mixing efficiency of Tai-Chi mixer.

Ozone and Fenton oxidation affected the bacterial community and opportunistic pathogens in biofilms and effluents from GAC

Granular activated carbon (GAC) filtration impacts pathogen colonization and bacterial communities in drinking water. However, the effects of ozone and heterogeneous Fenton oxidation on microbial community composition, in particular opportunistic pathogens (OPs), and their metabolic potential in biofilms and effluents from GAC filtration are not fully understood. The results of our pilot-scale test indicated that Fenton-GAC filtration removed more dissolved organic carbon (DOC, 1.25 mg/L) than ozone-GAC filtration (0.98 mg/L). Excitation-emission matrix (EEM) results showed that Fenton-GAC removed more tyrosine-like proteins and fulvic acid-like materials, while ozone-GAC removed more humic acid-like compounds and tryptophan-like proteins. Illumina HiSeq analysis indicated that Curvibacter and Hydrogenophaga dominated in the Fenton-GAC biofilm, while Bradyrhizobium, Aquabacterium and Limnobacter were predominant in the ozone-GAC biofilm. Functional prediction suggested that the microbial functional gene related to glyoxylate and dicarboxylate metabolism (the pathway for carbohydrate metabolism) was higher in the Fenton-GAC biofilm, resulting in higher contents of protein in extracellular polymeric substances (EPS) in the Fenton-GAC biofilm. Therefore, there were fewer bacteria that detached from the biofilm into the water during the Fenton-GAC filtration process. The lower EPS content in the effluents from Fenton-GAC resulted in bacteria, including OPs, being easier to remove by chlorine. However, ozone oxidation removed more bacteria, including different OPs, than Fenton oxidation, which contributed to fewer bacteria and OPs in the effluents from ozone-GAC. Overall, our results provide a Fenton-GAC treatment process to remove DOC and control OPs in drinking water systems, the cost of which was comparable to that of ozone-GAC.

Enhanced Fenton removal of phenol catalyzed by a modified red mud derived from the reduction of oxalic acid and L-ascorbic acid.

Red mud, a bauxite residue generated during alumina production through the Bayer process, contains oxides of Fe, Ti, Al, Mn, and rare earths, and has a latent performance for catalytic removal of phenol. We proposed a novel and facile approach for red mud modification by the reduction of oxalic acid and L-ascorbic acid in the acidic solution. By surveying characteristics of modified red mud and influencing factors of phenol removal, the optimum experiment conditions and the possible mechanism were explored, respectively. The results demonstrated that RO2V2 (treated red mud using 2 g of oxalic acid dehydrate and 2 g of L-ascorbic acid) and RO3V3 (treated red mud using 3 g of oxalic acid dehydrate and 3 g of L-ascorbic acid) showed the most efficient catalytic capacity for the phenol removal and removal efficiency of over 99.1% for the 200 mg/L of phenol solution within 5 min among investigated catalysts with the pH decreasing from 6.7 to 3. The excellent catalytic performance of modified red mud profited from the production of Fe3O4, Fe2O3, Mn2O3, Fe2SiO4, and FeTiO3 in the catalysts. It was motivating for removal of phenol to increase the dosage of catalyst and H2O2. The rate constants of the pseudo-first-order kinetics model of RO2V2 and RO3V3 were 1.0 and 1.073, respectively. The results of continuous experiments provided a positive reference for a future pilot scale test.