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Oxidation-reduction potential (ORP) sensors would constitute a robust surveillance and control solution for aeration and external carbon dosing in wastewater biological treatment processes if a clear correlation exists between the ORP values and process variables (e.g., dissolved oxygen (DO), nitrate, and chemical oxygen demand (COD). In this study, ORP values and other water quality variables were analyzed, and principal component analysis (PCA) and analysis of variance were used to study the relationships between ORP and main reactive substances under anoxic conditions. Mathematical models were then established using multiple regression analysis. The results showed that under anoxic conditions, ORP was positively correlated with nitrate, DO, and COD and negatively correlated with ammonia nitrogen, phosphate, and pH. COD had a low correlation with the ORP value change. PCA showed that the mathematical model of ORP can be established by using DO, nitrate, and phosphate, for which the adjusted R² value was 0.7195. The numeric relationships among ORP, COD, and nitrate were clearly established and applied to control external carbon dosing. A precise and clear relationship between ORP and COD offers the possibility to substitute COD monitoring for process control.

The quantitative analysis of biomass is essential for the research and application of moving bed biofilm reactors (MBBRs). However, the difficulty in measuring the attached growing biomass hinders the quantitative analysis of biofilm processes. In this study, a pilot-scale MBBR system was established to investigate biofilm evolution. The quantity of active heterotrophic and autotrophic biomass was measured throughout the entire culturing process. The total active biomass reached 250 mg COD/m

To explore the microbial nitrogen metabolism of a two-stage anoxic/oxic (A/O)-moving bed biofilm reactor (MBBR), biofilms of the system's chambers were analyzed using metagenomic sequencing. Significant differences in microbial populations were found among the pre-anoxic, oxic and post-anoxic MBBRs (P 0.01). Nitrospira and Nitrosomonas had positive correlations with ammonia nitrogen (NH

In the present paper, the information on the influence of various factors on the carbon block cartridges production technology and their potential impact on the properties of the finished product is presented. The possibilities of increasing the sorption-filtering efficiency of carbon block cartridges are presented. The technical and exploitation characteristics are influenced by the size of the mixture components granules, the physicochemical properties of active carbon and binder polymers, their ratio in the mixture, and the addition of bactericidal additives into the composition. The study of this topic is relevant, as evidenced by the analysis of the increasing number of publications on this matter over the past ten years. However, the production technology of carbon block cartridges is the know-how of manufacturing companies. This information is confirmed by the analysis of the technical characteristics of sixty carbon block cartridges from nine world manufacturers, whose products are WQA certified according to the NSF/ANSI 42 standard. The recommendations given by a number of authors on the size of activated carbon granules in the range from 40 to 120 mesh and polyethylene particles from 80 to 160 mesh with a flow rate of 1.4-3 g/10 min, can be taken as "reference points" in the development of extrusion mixtures with different components ratio. The following factors play an important role in obtaining effective cartridges: the quality of pre-extrusion mixing of the composition, its resistance to delamination during the “transition” from the mixer to the extruder loading zone, extrusion temperature regimes by zones, product cooling temperature, backpressure on the billet leaving the extruder. The information given in this article will be useful when producing new carbon block cartridges, improving the parameters of existing technologies, as well as in the research development of cartridges with new properties. У даній роботі наведено інформацію про вплив різних факторів на технологію виробництва картриджів з вугільних блоків та їх потенційний вплив на властивості готового виробу. Показано можливості підвищення сорбційно-фільтрувальної ефективності вугільних блочних картриджів. Встановлено, що на технікоексплуатаційні характеристики готового виробу впливають такі фактори: розмір гранул компонентів суміші, фізико-хімічні властивості активного вугілля і полімерів, їх співвідношення в суміші, додавання до складу бактерицидних добавок. Вивчення цієї теми є дуже актуальним, про що свідчить аналіз кількості публікацій за останні десять років. Проте, технологія виробництва картриджів карбон-блоків є ноу-хау компаній виробників. Цю інформацію підтверджує аналіз технічних характеристик шістдесяти картриджів карбон-блок від дев'яти світових виробників, продукція яких сертифікована WQA за стандартом NSF/ANSI 42. Наведені рядом авторів рекомендації щодо розміру гранул активованого вугілля в діапазоні від 40 до 120 меш і поліетиленових частинок від 80 до 160 меш з витратою 1,4-3 г/10 хв можна прийняти як «еталонні» при розробці екструзійних сумішей з різним співвідношенням компонентів. Виявлено, що для отримання ефективних картриджів важливу роль відіграють такі фактори: якість передекструзійного змішування композиції, її стійкість до розшарування при «переході» із змішувача в зону завантаження екструдера, температурні режими екструзії по зонах, температура охолодження продукту, тиск на заготовку, що виходить з екструдера. Інформація, наведена у даній статті, буде корисна при створенні нових виробництв картриджів карбон-блок, при покращенні параметрів існуючих технологій, а також при науково-дослідній розробці картриджів з новими властивостями.

Real-time monitoring of antibiotics in hospital and pharmaceutical wastewater using ultraviolet–visible (UV–Vis) spectroscopy is considered a promising method. Although gas chromatography–mass spectrometry (GC–MS) and other methods can detect antibiotics with quite low limits of detection (LOD), they possess various limitations. UV–Vis spectroscopy combined with chemometric methods is a promising choice for monitoring antibiotics. In this study, two immersed in situ UV–Vis sensors were used to explore the relationship between absorption spectra and antibiotics and study the influence of the optical path length on the LOD. The LODs of sensor 2 using a 10 cm optical path is up to 300 times lower than that of sensor 1 using a 0.5 mm optical path. Moreover, multiple antibiotics in the wastewater were investigated in real-time manner. The absorption spectra of 70 groups of wastewater samples containing different concentrations of tetracycline, ofloxacin, and chloramphenicol were measured. The results indicate that the nine wavelengths selected by interval partial least squares (iPLS) after the second derivative pretreatment have better predictability for ofloxacin and the six wavelengths selected by competitive adaptive reweighted sampling (CARS) after the first derivative. The multi-fold cross-validation results indicate that the model has a good predictive ability.

One of the main challenges in pet roleum-containing wastewater treatment in municipal wastewater treatment plants is their interference with the microbiological processes of nitrogen and phosphorus removal. The purpose of the study is to assess the effect of commercial petroleum products on the conversion of nitrogen and phosphorus compounds during the biological treatment of municipal wastewater in activated sludge systems. The presence of commercial petroleum products in wastewater was found to inhibit the process of conversion of NH4-N and the absorption of PO4-P in cells. The main inhibiting effect results from additives introduced into commercial petroleum products. Variations in the removal efficiencies of NH4-N and PO4-P are due to the variable distribution of commercial petroleum products in the mixed liquor of activated sludge. An increase in the degree of dispersion of commercial petroleum products, which results in an increase in the contact surface, increases the inhibitory effect on the activated sludge process. The toxic effect of gasoline is more pronounced in comparison with diesel fuel and hydraulic oil. During the first 30 minutes of incubation of samples with oil products, an increase in the concentration of PO4-P in the solution was observed due to the death of microorganisms from toxic effects, mainly from gasoline.

Biochar and chitosan are considered as green and cost-effective adsorbents for water purification, the combination of these two materials may lead to an improved adsorption capacity of the generated adsorbents. Most sorption studies have been focused on the ability to adsorb one contaminant or the same type of contaminants. Thus, this study aimed to produce chitosan-biochar beads (CH-BB) and test their efficiency in the simultaneous removal of a metal-complexing antibiotic, ciprofloxacin (CIP), and three metal(loid)s (As, Cd and Pb). Modification of raw pig manure biochar resulted in an increase in its adsorption capacity, except for Pb. The highest increment was observed for As (almost 6-fold) and the lowest was observed for CIP (1.1-fold). The adsorbent was able to simultaneously remove all targeted contaminants, individually and in the mixture. The adsorption capacity of CH-BB followed the order: Pb &gt, Cd &gt, &gt, As &gt, CIP. When Pb and As were present in the same mixture, their removal efficiency increased from 0.13 ± 0.01 to 0.26 ± 0.05 mg/g for As and from 0.75 ± 0.08 to 0.85 ± 0.02 mg/g for Pb due to their co-precipitation. The CIP–metal complexation probably resulted in a reduced adsorption ability for inorganics due to the decreased concentration of free ions. The presence of metals and metalloids led to alterations in CIP’s mobility.

Positive effects of retrofitting MBBR and IFAS systems into MBRs can be exploited by introducing chemical enhancement applying coagulants in the membrane separation step. The current study reports basic principles of chemical enhancement with aluminium sulphate coagulant in biofilm-MBR (Bf-MBR) based on results of total recycle tests performed at different dosages of the chemical enhancer and properties characterization of filtrates, supernatants and sediments. It demonstrates a possibility to achieve lower membrane fouling rates with dosing of aluminium sulphate coagulant into MBBR and IFAS mixed liquors by extending operational cycles by 20 and 80 time respectively as well as increasing operating permeability of membrane separation by 1.3 times for IFAS. It has been found that charge neutralization is the dominating mechanism of aluminium sulphate action as a chemical enhancer in Bf-MBR, however, properties of the membrane surface influencing charge repulsion of foulants should be considered together with the secondary ability of the coagulant to improve consolidation of sediments.

Considering new legislative and economic restrictions caused by the water crisis, this work focuses on a more efficient wastewater treatment process, which combines biological treatment in a moving bed biofilm system with a membrane bioreactor (BF-MBR) and coagulation, particularly addressing fouling alleviation in the separation stage. The study justifies the positive impact of coagulant dosing in BF-MBR regarding membrane flux and fouling rate. Statistical techniques connect the results of coagulation and membrane separation experiments with properties of mixed liquor, obtained after biotreatment in the representative pilot plant and characteristics of prepolymerized and non-prepolymerized inorganic coagulants. Research results substantiate the need for a pH-controlled coagulation of mixed liquor in BF-MBR depending on coagulant type, which influences charge, hydrophobicity and size of flocs and organic content of the system. It is suggested, that the adsorption/charge neutralization mechanism dominates in flux enhancement in BF-MBR, giving the best results in the case of prepolymerized aluminium coagulants. Together with high quality of permeate, the application of prepolymerized aluminium chloride of medium basicity entails a tenfold increase in filtration time of the membrane separation cycle and increases net membrane flux by 30–56%. The results of the study are practically significant for the development of an automated control system for BF-MBR, optimizing treatment rates together with membrane separation efficiency.

In the present work an optimization analysis of the main operating costs of the Black Sea water demineralization processes has been carried out. Several conventional and unconventional technologies utilizing membrane and ion exchange methods were considered. It is demonstrated that a double-stage reverse osmosis employing medium and low density membranes can be successfully used instead of conventional high pressure reverse osmosis for the demineralization of the Black Sea water. This allows decreasing main operating costs by 15–28%. Potable water can be obtained in membrane process without final remineralization by applying double-stage process based on nanofiltration and low density membrane elements. Main operating costs are by 15–35% lower compared with conventional seawater treatment processes.

Membrane fouling highly limits the development of Membrane bioreactor technology (MBR), which is among the key solutions to water scarcity. The current study deals with the determination of the fouling propensity of filtered biomass in a pilot-scale biofilm membrane bioreactor to enable the prediction of fouling intensity. The system was designed to treat domestic wastewater with the application of ceramic microfiltration membranes. Partial least squares regression analysis of the data obtained during the long-term operation of the biofilm-MBR (BF-MBR) system demonstrated that Mixed liquor suspended solids (MLSS), diluted sludge volume index (DSVI), chemical oxygen demand (COD), and their slopes are the most significant for the estimation and prediction of fouling intensity, while normalized permeability and its slope were found to be the most reliable fouling indicators. Three models were derived depending on the applied operating conditions, which enabled an accurate prediction of the fouling intensities in the system. The results will help to prevent severe membrane fouling via the change of operating conditions to prolong the effective lifetime of the membrane modules and to save energy and resources for the maintenance of the system.

Membrane bioreactor (MBR) is a progressive alternative to conventional waste-water treatment. However, membrane fouling is one of the most significant barriers to further development of the MBR technology since it has a detrimental effect on system performance and stability. Therefore, a number of studies have been developed to comprehend the fouling nature and distinguish the effective flux enhancers, so as to develop a highly effective fouling control strategy. Key findings of these studies are summarized in the current review. Polysaccharides, proteins and humic substances tend to play the prime role in inducing fouling. The main factors affecting fouling behaviour in MBRs are membrane characteristics, membrane operation conditions and activated sludge properties, and recent evidence points out that the modification of the biomass characteristics with the use of chemical agents and adsorbents is among the most efficient fouling-hindering techniques. The current review not only aims to provide a comprehensive overview of the up-to-date methods of fouling alleviation using membrane flux enhancers in MBR but also intends to shed light on the mechanisms of their action, which, together with the experience of previous findings, can be the basis for developing a new advanced fouling mitigation strategy.