Full-scale Process Research Articles

Occurrence and Ecological Risk Assessment of Highly Toxic Halogenated Byproducts during Chlorination Decolorization of Textile Printing and Dyeing Wastewater.

Textile printing and dyeing wastewater is a substantial source of highly toxic halogenated pollutants because of the chlorination decolorization. However, information on the occurrence and fate of the highly toxic halogenated byproducts, which are produced by chlorination decolorization of the textile printing and dyeing wastewater, is very limited. In this study, the occurrence of six categories of halogenated byproducts (haloacetic acids (HAAs), haloacetonitriles (HANs), N-nitrosamines (NAs), trihalomethanes, halogenated ketones, and halonitromethanes) was investigated along the full-scale treatment processes of textile printing and dyeing wastewater treatment plants. Furthermore, the ecological risk of the halogenated byproducts was evaluated. The results showed that the total concentration of halogenated byproducts increased significantly after chlorination. Large amounts of HAAs (average 122.1 μg/L), HANs (average 80.9 μg/L), THMs (average 48.3 μg/L), and NAs (average 2314.3 ng/L) were found in the chlorinated textile wastewater, and the results showed that the generations of HANs and NAs were positively correlated with the BIX and β/α index, indicating that the HANs and NAs might form from the microbial metabolites. In addition, HAAs and HANs exhibited high ecological risk quotients (>1), suggesting their high potential ecological risk. The results also demonstrated that most halogenated byproducts could be effectively removed by reverse osmosis treatment processes except NAs, with a lower removal rate of 18%. This study is believed to provide an important theoretical basis for controlling and reducing the ecological risks of halogenated byproducts in textile printing and dyeing wastewater effluents.

H2S mitigation for biogas upgrading in a full-scale anaerobic digestion process by using artificial neural network modeling

Biogas production by anaerobic digestion (AD) has emerged as a prominent bio-renewable energy source in recent years. However, the process also produces undesirable by-products, including H2S, thereby negatively impacting the biogas quality. This study focused on mitigating H2S in a full-scale AD located at a wastewater treatment plant (WWTP) by controlling the internal operational parameters by using an artificial neural network (ANN) model. Data from 54 days of AD operation were used to train and validate a structured ANN with a 5-3-1 topology. To minimize the H2S content, optimum values for dry solid (DS), volatile solid (VS), pH, temperature, and primary sludge fraction (PS) were determined to be 6.2 %, 63 %, 7.7, 35.6 °C, and 67.6 %, respectively, using the particle swarm optimization (PSO) algorithm. This optimization indicated a 49 % reduction in the average H2S concentration, from 6117 ppm to 3107 ppm. The analysis of relative importance (RI) showed that the pH (RI = −29.5) and PS (RI = −28.7) were the most critical factors affecting biogas quality. Additionally, several solutions derived from the optimization results were practically implemented in the Qom WWTP to achieve optimal conditions, and the outcomes were discussed.

Performances of full-scale biological nitrogen pre-treatment process for drinking water source: Seasonal variations and microbial community

This study investigated the performance of the full-scale unit over a two-year period to enhance nitrification efficiency and provide operational strategies. Results indicated that raw water quality from Donggan River was notably influenced by seasonal variations, particularly during dry and wet seasons, impacting the nitrification efficiency of the biological pretreatment process. Factors such as influent concentrations of ammonia and total Kjeldahl nitrogen were found to have significant effects on nitrification, with temperature and conductivity also showing correlations. The specific rate of ammonia removal was calculated to be approximately 0.1 kg-N/m3/d under the existing operational setup. Moreover, elevating dissolved oxygen levels above 4 mg/L was proposed to potentially boost ammonia oxidation based on findings from experiments conducted in lab-scale bioreactors. In times of increased influent ammonia levels, the elimination of about 1–3 mg-N/L of total nitrogen signified the activation of denitrification processes. This observation was corroborated by results from next-generation sequencing techniques, verifying the existence of denitrifying microorganisms. The real-time PCR analysis results indicated that the abundance of comammox amoA gene was comparable with the abundance of the AOB amoA gene, indicating the presence of comammox Nitrospira and their potential role on nitrification in the system.

Data mining process to detect suicidal behaviour in out-of-hospital emergency departments

Out-of-hospital emergency departments receive multiple types of requests daily. Their management requires a balance to be found between available resources and the actual needs of the requesting party. Those regarding suicidal behaviour, which are resource heavy, are few in number in terms of the bulk of requests, and detecting them correctly is therefore important. Previous research, using machine learning algorithms to analyse suicide, has typically focused on discovering insights to be used by medical personnel. This proposal extends its use in two directions: knowledge that can be used by non-exclusively medical staff, such as telephone operators, and the models that have been incorporated into a software prototype to help in the decision-making of an emergency department. In addition, previous research has often included a range of information from different sources that are not available when processing an emergency call request, for example, data that is only obtained at the end of the intervention. A full-scale data mining process has been performed using data from the out-of-hospital emergency service in Malaga (Spain). Sensitivity has been the primary goal to avoid missing cases requiring special attention, but this objective has been pursued without overlooking a good trade-off with specificity. The best models can offer such a compromise between sensitivity and specificity, and show more than 80% in both metrics simultaneously. The experts validate that the modelling phase showed that the algorithms have automatically identified already known situations. This lays the groundwork for further iterations with a promising outlook.

Molecular-level insights into dissolved organic matter and its variations of the full-scale processes in a typical petrochemical wastewater treatment plant

Petrochemical wastewater (PCWW) treatment poses challenges due to its unique and complex dissolved organic matter (DOM) composition, originating from various industrial processes. Despite the addition of advanced treatment units in PCWW treatment plants to meet discharge standards, the mechanisms of molecular-level sights into DOM reactivity of the upgraded full-scale processes including multiple biological treatments and advanced treatment remain unclear. Herein, we employ water quality indexes, spectra, molecular weight (MW) distribution, and Fourier transform ion cyclotron resonance mass spectrometry to systematically characterize DOM in a typical PCWW treatment plant including influent, micro-oxygen hydrolysis acidification (MOHA), anaerobic/oxic (AO), and micro-flocculation sand filtration–catalytic ozonation (MFSF–CO). Influent DOM is dominated by tryptophan-like and soluble microbial products with MW fractions 〈 1 kDa and 〉 100 kDa, and CHO with lignin and aliphatic/protein structures. MOHA effectively degrades macromolecular CHO (10.86 %) and CHON (5.24 %) compounds via deamination and nitrogen reduction, while AO removes CHOS compounds with MW < 10 kDa by desulfurization, revealing distinct DOM conversion mechanisms. MFSF–CO transforms unsaturated components to less aromatic and more saturated DOM through oxygen addition reactions and shows high CHOS and CHONS reactivity via desulfurization and deamination reactions, respectively. Moreover, the correlation among multiple parameters suggests UV254 combined with AImod as a simple monitoring indicator of DOM to access the chemical composition. The study provides molecular-level insights into DOM for the contribution to the improvement and optimization of the upgraded processes in PCWW.

Process Energy and Material Consumption Determined by Reaction Sequence: From AAO to OHO

The anaerobic-anoxic-oxic (AAO) process is one of the most widely used processes for treating industrial organic wastewater, and it has shown significant effectiveness in the removal of organic compounds, as well as denitrification and phosphorus removal. However, for the treatment of industrial organic wastewater, this anaerobic preposition and aerobic postposition process has exposed various limitations. Therefore, for this type of wastewater, the oxic-hydrolytic and denitrification-oxic (OHO) treatment process has been proposed and developed based on the principles of three-sludge separation and fluidization. This study integrated operational data from 203 coking wastewater treatment plants worldwide, and the two-step nitrification-denitrification activated sludge model No.3 (TCW-ASM3) was used for comparative analysis of the pollutant removal efficiency and total operating cost of the AAO process and the OHO process in the face of characteristic pollutants in coking wastewater. The results indicate that the full-scale OHO process achieved removal efficiencies of up to 3784 mg/L for chemical oxygen demand (COD) and 297 mg/L for total nitrogen (TN). The theoretical total cost for OHO and AAO were 9.75 and 14.38 CNY/m3, respectively. The pre-treatment aerobic process effectively reduces the biological toxicity of high-toxicity and refractory industrial wastewater, and the three-sludge system provides a stable living space for functional microorganisms, the combination of multi-mode denitrification processes offers new possibilities for treating similar types of industrial wastewater.

Power feasibility of single-staged full-scale PRO systems with hypersaline draw solutions

Pressure retarded osmosis (PRO) is a process that allow to generate energy from osmotic gradient. This process uses selective membranes in order to produce electrical energy through a hydraulic turbine. PRO can be used as a renewable energy technology where water resources are inexhaustible. PRO has the advantage of knowing when and how much energy will be produced. Unfortunately at the moment there are certain limiting factors concerning membrane and module characteristics that have prevented PRO to be fully exploited at full-scale. This study aims to assess the impact of hypersaline draw solutions (60–180 g L−1), membrane characteristics such as structural parameter, module membrane surface and permeability coefficients on the net energy generated by single-staged full-scale PRO system with up to 8 spiral wound membrane modules (SWMMs) in series in a pressure vessel. To carry out this study, characteristics of existing PRO membranes at lab-scale were scaled up to 8 inches SWMM. The results showed the change in the optimal operating parameters with the change of membrane characteristics and draw solution concentration. This study concluded that single-staged full-scale PRO process would be viable from an energy point of view if membranes were manufactured on an industrial scale and with the characteristics of existing membranes on a laboratory scale.

Elements of a doctrine of transnational constitutional norms

Abstract This article uses the traditions of constitutionalism to develop the building blocks of a doctrine of transitional constitutional norms. After arguing that existing doctrines of implicit constitutional unamendability, such as the basic structure and constitutional replacement doctrines, are derivative, the article provides an account of the underlying primary doctrine: transnational constitutional norms. From the perspective of the form of government, constitutional norms are divided into peremptory and voluntary norms. Unearthing an old, but now largely forgotten, tradition of political thought, it defines peremptory norms as norms that derive from or constitute the form of government. These constitutional norms have a complex nature: domestic and transnational. The transnational dimension immunizes the people’s choice in favor of the democratic form of government by protecting peremptory norms from deselection, defined as the impermissible alteration or replacement of that form of government through piecemeal derogation from peremptory norms. Only the people as pouvoirconstituant, but not their representatives, may chose the form of government and only through a full-scale process of constitution-making. The article uses judicial independence to illustrate the idea of peremptory constitutional norms. The doctrine of transnational constitutional norms helps to resist attempts at undermining judicial independence and to protect the integrity of the democratic form of government against impermissible deselection.

Seasonal tourism's impact on wastewater composition: Evaluating the potential of alternating activated adsorption in primary treatment

Primary treatment processes have gained attention in recent research and development due to their potential for redirecting carbon towards anaerobic digestion, which can subsequently be used for the production of biomethane. The alternating activated adsorption (AAA) process is implemented on full-scale at several wastewater treatment plants across Europe. However, there is a lack of full-scale studies of advanced carbon capture technology implementations in literature. This study demonstrates the ability of a full-scale AAA process to remove and redirect carbon in a region heavily influenced by tourism. Periods in high and off-season were compared to study the impact of tourism on the composition of the wastewater and the AAA-process. The wastewater characteristics of the high season differed significantly from the low season. During the high season, the PE increased by 37 %, total suspended solids went up by 75 % and chemical oxygen demand increased by 58 %, compared to the low season. Additionally, 80 % of the low volatile lipophilic substances (LVLS) measured were attributed to the impact of tourism. A mass-balance of primary treatment for chemical oxygen demand (COD) and LVLS was conducted for both trial periods. The primary treatment was able to eliminate 56 % of the COD and 62 % of the LVLS in the non-tourist season and 53 % of the COD and 54 % of the LVLS in the tourist season. The increased wastewater load was effectively managed in the AAA-process. Key process parameters like sludge settling characteristics, hydraulic retention time and total suspended solids removal rates remained stable during the high season in winter.

Evaluation of aircraft deicing fluid as an external carbon source for denitrification

Water resource recovery facilities (WRRFs) performing biological nitrogen removal (BNR) often require external carbon sources for meeting nitrogen discharge permit limits. This brings an additional financial burden to the facilities considering the continuous need of these external carbon sources. This paper evaluates the utilization of airport stormwater, which in the winter season is rich in aircraft deicing fluid (ADF) as an alternative external carbon source. Denitrification and nitrification bench scale experiments were performed to assess the efficacy of external carbon sources to remove nitrogen in WRRFs. Experimental results showed that ADFs achieve denitrification rates of 0.064–0.066 d−1, higher than what achieved by a commercial carbon source, MicroC 2000A, with corresponding value of 0.058 d−1 at low temperatures, as low as 13 °C, which is considered a worst-case scenario for nitrogen removal efficiency. Furthermore, no inhibition to nitrification associated with the ADFs was observed. Subsequently a dynamic modeling study was conducted to assess the performance of ADFs as external carbon sources for denitrification and compared them to the conventional source that was being used in a full-scale BNR process. Results from the dynamic modeling study revealed that if 40 % of the spent-ADF at LaGuardia airport, New York City, could be collected with the stormwater and conveyed to a WRRF via the sewer collection system, an approximate reduction of 30 % of the commercial external carbon source could be accomplished by repurposing a waste product. This study contributes to the potential of ADF as a denitrification aid and an alternative for commercially available carbon sources with comparable nitrogen removal efficiencies.

Effect-based monitoring of chemical hazards in drinking water from source to tap: seasonal trends over 2 years of sampling

Drinking water producers have a far-reaching responsibility to provide safe, clean and wholesome drinking water, using water resources possibly effected by the thousands of chemicals used in societies’ daily life. This study has monitored chemical hazards in drinking water from source to tap, using effect-based methods. The study was conducted at a Swedish drinking water treatment plant sourcing lake water and aimed to investigate potential seasonal variations in both the raw water and water after different treatment steps. Furthermore, a granular activated carbon (GAC) pilot facility was evaluated. Samples were analyzed for estrogenicity, androgenicity, aryl hydrocarbon receptor (AhR) activity, oxidative stress (Nrf2) response and genotoxicity (micronucleus formation). We observed seasonal differences in oxidative stress and genotoxic effects in both raw and drinking water with higher activities during the late fall of each year. The removal efficiency for both oxidative stress and genotoxicity was limited in the full-scale treatment process and occasionally the genotoxicity was also detected in outgoing drinking water from the treatment plant and in samples collected at consumers tap on the distribution network. AhR activity was present in all raw water samples and the removal was limited. Estrogenic activities were observed in most of the raw water samples but in contrast to the other parameters estrogenicity was effectively reduced by the full-scale conventional treatment. The GAC pilot treatment was generally more efficient than the full-scale conventional treatment in removing all observed bioactivities and could be a viable complement to the current treatment to assure drinking water free from genotoxic compounds. Genotoxic activities in drinking water was observed while all currently regulated chemical parameters were fulfilled. This highlights the need for effect-based monitoring in efforts to ensure the chemical safety of drinking water, as target chemical analysis of single compounds will overlook both unknown hazardous compounds as well as potential mixture effects.Graphical

Application of design of experiments (DoE) in evaluating crushing-screening performance for aggregates production

The configuration and the interaction between the crushers and screens enable aggregate producers to produce products that are in accordance with the applicable product certification. However, the performance of the system is seldom optimized for the given conditions and market demand. This paper aims to describe the experimental work and the results of quantifying the crusher and screen performance by applying the design of experiments (DoE) in a full-scale tertiary crushing process of an aggregate production plant with both standard belt-cut sampling as well with continuous processes monitoring. The results show the application of a simplified modelling approach using the design of experiments for the evaluation of crusher performance and circuit performance using experimental data. The research output is able to demonstrate that there exists an interaction effect between the crusher closed side setting and eccentric speed that previously has not been identified with traditional methods. The quantification of interaction between crusher and screen individual performance to the process performance has been demonstrated with both belt-cut samples and continuous process monitoring. Using a DoE, digital experiments can be planned for mapping and quantifying the performance of aggregate production.

Using TOXCHEM model for simulation the hydrogen sulfide behavior in a full-scale MBBR process

Odors emanating from treatment plants are a source of concern for those working in these plants. Hydrogen sulfide gas is the most dangerous aromatic compound for WWTP workers and plant equipment and facilities. In this study, hydrogen sulfide gas was modeled using the TOXCHEM model of the Aoun sewage treatment plant, which operates with the MBBR system. The TOXCHEM model was calibrated and validated and the results were within the R and RMSE parameters. Sensitivity analysis was studied on the most important factors affecting the emission of hydrogen sulfide gas in the Aoun sewage treatment plant. The results showed that the most important processes that obtain hydrogen sulfide gas are biodegradation, absorption, emission or volatilization. The results in winter, (12 °C), and summer (35 °C) about 6% and 8%, 18% and 17%, 72% and 65%, 0% and 0%, and 4% and 10% were fated as emitted to air, sorbed to sludge, discharged with effluent, biodegraded, and treated with odor removal system, respectively. The highest emission of hydrogen sulfide gas was observed in the preliminary stage (lift station, course and fine screen, API, and equalization tank), especially in the API basin, where it reached 1.8 ppm. Increasing temperatures, the air flow rate, decreasing the value of pH, increasing the flow and increasing the filling time in the pumping station all cause an increase in the emission of hydrogen sulfide gas. Modeling hydrogen sulfide gas by TOXCHEM model gave an excellent prediction to control the emission of hydrogen sulfide gas for decision makers in the plant.

Assessing the performance of polyphosphate accumulating organisms in a full-scale side-stream enhanced biological phosphorous removal.

Phosphorous (P) removal in wastewater treatment is essential to prevent eutrophication in water bodies. Side-stream enhanced biological phosphorous removal (S2EBPR) is utilized to improve biological P removal by recirculating internal streams within a side-stream reactor to generate biodegradable carbon (C) for polyphosphate accumulating organisms (PAOs). In this study, a full-scale S2EBPR system in a water resource recovery facility (WRRF) was evaluated for 5 months. Batch experiments revealed a strong positive correlation (r = 0.91) between temperature and C consumption rate (3.56-8.18 mg-COD/g-VSS/h) in the system, with temperature ranging from 14°C to 18°C. The anaerobic P-release to COD-uptake ratio decreased from 0.93 to 0.25 mg-P/mg-COD as the temperature increased, suggesting competition between PAOs and other C-consumers, such as heterotrophic microorganisms, to uptake bioavailable C. Microbial community analysis did not show a strong relationship between abundance and activity of PAO in the tested WRRF. An assessment of the economic feasibility was performed to compare the costs and benefits of a full scale WRRF with and without implementation of the S2EBPR technology. The results showed the higher capital costs required for S2EBPR were estimated to be compensated after 5 and 11 years of operation, respectively, compared to chemical precipitation and conventional EBPR. The results from this study can assist in the decision-making process for upgrading a conventional EBPR or chemical P removal process to S2EBPR. PRACTITIONER POINTS: Implementation of S2EBPR presents adaptable configurations, exhibiting advantages over conventional setups in addressing prevalent challenges associated with phosphorous removal. A full-scale S2EBPR WRRF was monitored over 5 months, and activity tests were used to measure the kinetic parameters. The seasonal changes impact the kinetic parameters of PAOs in the S2EBPR process, with elevated temperatures raising the carbon demand. PAOs abundance showed no strong correlation with their activity in the full-scale S2EBPR process in the tested WRRF. Feasibility assessment shows that the benefits from S2EBPR operation can offset upgrading costs from conventional BPR or chemical precipitation.

Deactivation of internal recirculation in a full-scale Biological Nutrient Removal (BNR) Wastewater Treatment Plant (WWTP) reveals outstanding microeukaryotic bioindicators

The bioindicator potential of the microeukaryotic community in a full-scale A2O wastewater treatment process was assessed after deactivating the internal recirculation in one of the two parallel treatment lines of the plant. The deactivation of the internal recirculation in one of the lines (NIR-line), led to a strong decrease in nitrogen removal efficiency (53 % ammonia-uptake in the NIR-line versus 97 % in the unaltered line or IR-line), as well as to a lower organic matter removal (95 % BOD5 removal versus 97 % in the IR-line). The microeukaryote community structure changed greatly confirming trends observed in experimental studies and showed a decrease in abundance and richness in the NIR-line. However, this line showed a significant higher abundance of certain ciliate species, such as Epistylis camprubii and Vorticellides infusionum, which are common species in conventional activated sludge. Conversely, the IR-line showed useful indicators of internal recirculation, associated with much higher ammonium and BOD5 removal. These results show that identification to ciliate species level provides a more reliable bioindication in nutrient removal systems, supporting the importance of research on biological parameters, mainly protists, as simple and useful tools for plant operators to manage nutrient removal processes. These observations extend the current boundaries of bioindication.

Emerging and legacy per- and polyfluoroalkyl substances (PFAS) in fluorochemical wastewater along full-scale treatment processes: Source, fate, and ecological risk

The increasing applications of emerging per- and polyfluoroalkyl substances (PFAS) have raised global concern. However, the release of emerging PFAS from the fluorochemical industry remains unclear. Herein, the occurrence of 48 emerging and legacy PFAS in wastewater from 10 fluorochemical manufacturers and mass flows of PFAS in a centralized wastewater treatment plant were investigated. Their distribution and ecological risk in neighboring riverine water were also evaluated. In wastewater from fluorochemical manufacturers, PFAS concentrations were in the range of 14,700–5200,000 ng/L and 2 H,2 H-perfluorooctanoic acid (6:2 FTCA), perfluorooctanoic acid (PFOA), N-ethyl perfluorooctane sulfonamide (N-EtFOSA), and 1 H,1 H,2 H,2 H-perfluorodecanesulfonate (8:2 FTS) were the major PFAS detected. Several PFAS displayed increased mass flows after wastewater treatment, especially PFOA and 6:2 FTCA. The mass flows of PFAS increased from − 20% to 233% after the activated sludge system but decreased by only 0–13% after the activated carbon filtration. In riverine water, PFAS concentrations were in the range of 5900–39,100 ng/L and 6:2 FTCA, 1 H,1 H,2 H,2 H-perfluorodecyl phosphate monoester (8:2 monoPAP), 1 H,1 H,2 H,2 H-perfluorooctyl phosphate monoester (6:2 monoPAP), PFOA, and perfluorohexanoic acid (PFHxA) were the major PFAS detected. PFOA and 6:2 FTCA exhibited comparable hazard quotients for ecological risk. Current wastewater treatment processes cannot fully remove various PFAS discharged by fluorochemical manufacturers, and further investigations on their risk are needed for better chemical management.

Metagenomic Insight Reveals the Microbial Structure and Function of the Full-Scale Coking Wastewater Treatment System: Gene-Based Nitrogen Removal

Microbial communities play crucial roles in pollutant removal and system stability in biological systems for coking wastewater (CWW) treatment, but a comprehensive understanding of their structure and functions is still lacking. A five month survey of four sequential bioreactors, anoxic 1/oxic 1/anoxic 2/oxic 2 (A1/O1/A2/O2), was carried out in a full-scale CWW treatment system in China to elucidate operational performance and microbial ecology. The results showed that A1/O1/A2/O2 had excellent and stable performance for nitrogen removal. Both total nitrogen (TN; (17.38 ± 6.89) mg·L−1) and ammonium–nitrogen (NH4+-N; (2.10 ± 1.34) mg·L−1) in the final biological effluent satisfied the Chinese national standards for CWW. Integrated analysis of 16S ribosome RNA (rRNA) sequencing and metagenomic sequencing showed that the bacterial communities and metagenomic function profiles of A1 and O1 shared similar functional structures, while those of A2 significantly varied from those of other bioreactors (p < 0.05). The results indicated that microbial activity was strongly connected with activated sludge function. Nitrosospira, Nitrosomonas, and SM1A02 were responsible for nitrification during the primary anoxic–oxic (AO) stage and Azoarcus and Thauera acted as important denitrifiers in A2. Nitrogen cycling-related enzymes and genes work in the A1/O1/A2/O2 system. Moreover, the hao genes catalyzing hydroxylamine dehydrogenase (EC 1.7.2.6) and the napA and napB genes catalyzing nitrate reductase (EC 1.9.6.1) played important roles in the nitrification and denitrification processes in the primary and secondary AO stages, respectively. The mixed liquor suspended solids (MLSS)/total solids (TS), TN removal rate (RR), total organic carbon (TOC) (RR), and NH4+-N (RR) were the most important environmental factors for regulating the structure of core bacterial genera and nitrogen-cycling genes. Proteobacteria were the potential main participants in nitrogen metabolism in the A1/O1/A2/O2 system for CWW treatment. This study provides an original and comprehensive understanding of the microbial community and functions at the gene level, which is crucial for the efficient and stable operation of the full-scale biological process for CWW treatment.

MiniMelt: An instrument for real-time tracking of electron beam additive manufacturing using synchrotron x-ray techniques.

The development of a sample environment for in situ x-ray characterization during metal Electron Beam Powder Bed Fusion (PBF-EB), called MiniMelt, is presented. The design considerations, the features of the equipment, and its implementation at the synchrotron facility PETRA III at Deutsches Elektronen-Synchrotron, Hamburg, Germany, are described. The equipment is based on the commercially available Freemelt ONE PBF-EB system but has been customized with a unique process chamber to enable real-time synchrotron measurements during the additive manufacturing process. Furthermore, a new unconfined powder bed design to replicate the conditions of the full-scale PBF-EB process is introduced. The first radiography (15kHz) and diffraction (1kHz) measurements of PBF-EB with a hot-work tool steel and a Ni-base superalloy, as well as bulk metal melting with the CMSX-4 alloy, using the sample environment are presented. MiniMelt enables time-resolved investigations of the dynamic phenomena taking place during multi-layer PBF-EB, facilitating process understanding and development of advanced process strategies and materials for PBF-EB.

Evaluation of Water Treatment Efficiency of Full-Scale Slow Sand Filtration Process: Comparison of Summer and Winter Season

Objectives : The objective of this study is to evaluate the feasibility of sustainable operation in a conventional full-scale slow sand filter process.Methods : A slow sand filtration process was operated in small scale water treatment plants for valley water. The water quality such as particle matter, dissolved organic matter, the number of bacteria, and disinfection by-product (DBP) were monitored at four designated points once a week and was compared during summer (July-August) and winter season (December-January).Results and Discussion : Although the number of particle matter in summer was higher than in winter by 39% (2.91×10&lt;sup&gt;4&lt;/sup&gt; /mL), particle matter in slow sand filter process was removed by 99% regardless of season (temperature). The removal efficiency of dissolved organic carbon (DOC) and UV&lt;sub&gt;254&lt;/sub&gt; was higher in summer than in winter by 15% and 21%, respectively. In addition, concerning the organic fraction, higher molecular weight led to higher removal efficiency in the following sequence: BP (biopolymer, MW: 20,000 g/mol) &gt; HS(humic substances, MW : 1,000~20,000 g/mol) &gt; BB(building blocks, MW : 300~500 g/mol) &gt; LMWs(low molecular weights, MW : 350 g/mol. The concentration of trihalomethanes (THMs) and haloacetic acids (HAAs), indicator of DBP, were detected at 12.2 and 9.4 μg/L in summer and 8.1 and 6.3 μg/L in winter, respectively, which would be considered very low concentration related to the drinking water regulation of 100 μg/L. Finally, the active bacteria was removed up to 93 and 92% in summer and winter, respectively.Conclusion : The feasibility of a slow filtration process was evaluated to compare particle and dissolved matter in summer and winter operation. Despite a 39% increase in particle matter in summer, the removal efficiency was maintained at 98% in summer and winter. Due to the increased activation of biofilm in summer, the removal of DOC and UV&lt;sub&gt;254&lt;/sub&gt; was higher in summer than winter by 15 and 21%, respectively. The significant low concentration of THMs and HAAs, regardless of season, would be negligible. In addition, achieving over 92% removal of activated bacteria secured the biological safety. These stable operations ensure that slow filtration process is effective in controlling of water quality.

Microplastic removal in batch and dynamic coagulation-flocculation-sedimentation systems is controlled by floc size

Most studies examining the removal of microplastics (MPs) during controlled bench-scale trials have applied high coagulant dosages, which are characteristic of sweep flocculation. As such the impact of other typical operating conditions remains largely unknown. The use of bench-scale jar testing is ubiquitous in the literature, however the hydrodynamics of a batch-type approach bear little resemblance to full-scale treatment processes. In this study, a range of microplastics sizes and types were employed to assess their removal via conventional jar tests as well as to compare results to a continuous-flow bench-scale system. Jar tests were performed to identify pH values and alum dosages that are optimal for MP reduction when considering a range of coagulation conditions. The production of large and readily settling aluminum hydroxide (Al(OH)3) floc represented the dominant condition driving MPs removal. However, total MP removal was observed to be lower during continuous-flow trials when compared to jar tests, suggesting that direct extrapolation of results from jar tests may overpredict performance observed at full-scale. Irrespective of microplastic type and size, strong correlations were observed between MP concentration and turbidity reduction, indicating that turbidity may potentially serve as a very useful surrogate. Significant correlations were observed when comparing both floc size, especially 90th percentile floc diameter, and concentration of floc >100 μm to the reduction of MPs.