Natural organic matter (NOM), a key component in aquatic environments, is a complex matrix of organic substances characterized by its fluctuating amounts in water and variable molecular and chemical ...properties, leading to various interaction schemes with the biogeosphere and hydrologic cycle. These factors, along with the increasing amounts of NOM in surface and ground waters, make the effort of removing naturally-occurring organics from drinking water supplies, and also from municipal wastewater effluents, a challenging task requiring the development of highly efficient and versatile water treatment technologies.
Advanced oxidation processes (AOPs) received an increasing amount of attention from researchers around the world, especially during the last decade. The related processes were frequently reported to be among the most suitable water treatment technologies to remove NOM from drinking water supplies and mitigate the formation of disinfection by products (DBPs). Thus, the present work overviews recent research and development studies conducted on the application of AOPs to degrade NOM including UV and/or ozone-based applications, different Fenton processes and various heterogeneous catalytic and photocatalytic oxidative processes. Other non-conventional AOPs such as ultrasonication, ionizing radiation and plasma technologies were also reported. Furthermore, since AOPs are unlikely to achieve complete oxidation of NOM, integration schemes with other water treatment technologies were presented including membrane filtration, adsorption and others processes.
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•O3, UV, Fenton-based processes and (photo)catalytic AOPs were overviewed.•AOPs are efficient to remove NOM from drinking water supplies.•Optimized AOPs helped reducing the formation potential of disinfection by-products.•Coupling AOPs with other water treatment processes improved NOM removal efficiency.
Wastewater treatment plants (WWTPs) are acting as routes of microplastics (MPs) to the environment, hence the urgent need to examine MPs in wastewaters and different types of sludge through sampling ...campaigns covering extended periods of time. In this study, the efficiency of a municipal WWTP to remove MPs from wastewater was studied by collecting wastewater and sludge samples once in every two weeks during a 3-month sampling campaign. The WWTP was operated based on the conventional activated sludge (CAS) process and a pilot-scale membrane bioreactor (MBR). The microplastic particles and fibers from both water and sludge samples were identified by using an optical microscope, Fourier Transform Infrared (FTIR) microscope and Raman microscope. Overall, the retention capacity of microplastics in the studied WWTP was found to be 98.3%. Most of the MP fraction was removed before the activated sludge process. The efficiency of an advanced membrane bioreactor (MBR) technology was also examined. The main related finding is that MBR permeate contained 0.4 MP/L in comparison with the final effluent of the CAS process (1.0 MP/L). According to this study, both microplastic fibers and particles are discharged from the WWTP to the aquatic environment.
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•Microplastic concentrations were studied in different stages of a municipal WWTP.•Microplastics were identified by visual identification, FTIR- and Raman-microscopy.•98.3% of microplastic load was removed during conventional WWTP processes.•MBR process had higher retention rate for microplastics than secondary CAS process.•Polyester fibers and polyethylene fragments were detected most frequently.
Natural organic matter (NOM) is a complex matrix of organic substances produced in (or channeled to) aquatic ecosystems via various biological, geological and hydrological cycles. Such variability is ...posing a serious challenge to most water treatment technologies, especially the ones designed to treat drinking water supplies. Lately, in addition to the fluctuating composition of NOM, a substantial increase of its concentration in fresh waters, and also municipal wastewater effluents, has been reported worldwide, which justifies the urgent need to develop highly efficient and versatile water treatment processes.
Coagulation is among the most applied processes for water and wastewater treatment. The application of coagulation to remove NOM from drinking water supplies has received a great deal of attention from researchers around the world because it was efficient and helped avoiding the formation of disinfection by products (DBPs). Nonetheless, with the increased fluctuation of NOM in water (concentration and composition), the efficiency of conventional coagulation was substantially reduced, hence the need to develop enhanced coagulation processes by optimizing the operating conditions (mainly the amount coagulants and pH), developing more efficient inorganic or organic coagulants, as well as coupling coagulation with other water treatment technologies. In the present review, recent research studies dealing with the application of coagulation for NOM removal from drinking water supplies are presented and compared. In addition, integration schemes combining coagulation and other water treatment processes are presented, including membrane filtration, oxidation, adsorption and others processes.
•Recent R&D studies in the field of NOM removal by coagulation are overviewed.•Various metallic and polymeric coagulants are included.•Biocoagulants are promising alternatives to conventional metal-based coagulants.•Novel composites are enabling efficient NOM removal from drinking water supplies.•Coagulation-based integrated processes for improved efficiency and resilience.
The harmonized procedures in terms of the sampling, sample treatment and identification of microplastics in different environmental samples are missing, which poses challenges to researchers to ...compare the results or to adopt ‘the most effective’ monitoring approach. Furthermore, in the related literature, the used procedures are rarely tested with spiked microplastics to predetermine their recovery rates. Without this knowledge, results should only be discussed as rough estimations of the real environmental concentrations of microplastics. In this study, six different methods previously used in microplastic studies of different media were tested with municipal wastewater and digested sludge samples, spiked with seven different types of plastic particles and fibres. Recovery rates, time consumption, advantages and disadvantages were assessed and most suitable treatment procedures (i.e. high recovery rates in short amount of time) were chosen for both wastewater and sludge. Suitability of staining with Rose Bengal was examined together with most efficient methods, but it did not improve the recovery of microplastics. In addition, the possible impacts of the treatments for identification with micro-Raman and FTIR microscope were assessed. Filtration with size fractioning was found to be the best method for both wastewater and sludge samples, with recovery rates of spiked microplastics around 91.4% and 92.9%, respectively.
This study investigates the removal and fate of 23 emerging organic micropollutants (EOMs) including a wide range of pharmaceuticals (antibiotics, β-blockers, analgesics, diuretics, psychostimulants, ...antiepileptics, immunosuppressives, anticoagulants), and steroid hormones detected in municipal wastewater by a pilot-scale membrane bioreactor (MBR) plant at two different solid retention times (SRTs) of 60 and 21 days. Different removal efficiencies of the selected EOMs were observed and explained based on their physicochemical properties (such as distribution coefficient, log D; dissociation constant, pKa; solid-water distribution coefficients, and Kd) along with process operating parameters. The dominant removal mechanisms of EOMs were biotransformation and sorption onto the sludge, which were confirmed by the mass balance study. Moreover, changes in the sludge properties, as a consequence of different SRTs, were evaluated based on variations in soluble microbial products (SMP), extracellular polymeric substances (EPS), and capillary suction time (CST). Finally, the quality of the MBR effluent was compared with some established guidelines, which confirmed the fulfilment of water quality requirements for reuse purposes.
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•Fate of 23 EOMs in pilot MBR treatment at varying SRT was studied.•At long SRT, EOMs removal majorly enhanced while SMP and EPS concentration lessened.•Hormones and antibiotics were highly removed than diuretics and anti-epileptics.•Iopamidol and hydrocortisone (>90% removal) were studied for the first time in MBR.•MBR Effluent fulfilled the water quality requirements for reuse.
In any single component isotherm study, determining the best-fitting model is a key analysis to mathematically describe the involved sorption system and, therefore, to explore the related theoretical ...assumptions. Hence, several error calculation functions have been widely used to estimate the error deviations between experimental and theoretically predicted equilibrium adsorption values (
Q
e
,
exp
vs
.
Q
e
,
theo
as
X- and
Y-axis, respectively), including the average relative error deviation, the Marquardt's percent standard error deviation, the hybrid fractional error function, the sum of the squares of the errors, the correlation coefficient and the residuals. In this study, five other statistical functions are analysed to investigate their applicability as suitable tools to evaluate isotherm model fitness, namely the Pearson correlation coefficient, the coefficient of determination, the Chi-square test, the
F-test and the Student's
T-test, using the commonly-used functions as references. The adsorption of textile dye onto
Posidonia oceanica seagrass fibres was carried out, as study case, in batch mode at 20
°C. Besides, and in order to get an overall approach of the possible utilization of these statistical functions within the studied item, the examination was realized for both linear and non-linear regression analysis. The related results showed that, among the five studied statistical tools, the
χ
2 and Student's
T-tests were suitable to determine the best-fitting isotherm model for the case of linear modelling approach. On the other hand, dealing with the non-linear analysis, despite the Student's
T-test, all the other functions gave satisfactorily results, by agreeing the commonly-used error functions calculation.
Batch biosorption experiments were carried out for the removal of methylene blue, a basic dye, from aqueous solution using raw
Posidonia oceanica (L.) fibres, a marine lignocellulosic biomass. A ...series of assays were undertaken to assess the effect of the system variables, i.e. contact time, solution pH, biosorbent dosage and initial dye concentration. The results had showed that biosorption capacity was optimal using 6–9 solution pH range and by increasing the biosorbent concentration up to 1
g/L. The biosorption kinetics were analyzed using irreversible-first-order, reversible-first-order and pseudo-second-order and the sorption data were very well described by the pseudo-second-order model for the entire adsorption time with squared correlation coefficients equal to unity for all experimented initial dye concentrations. Besides, equilibrium data were very well represented by both Langmuir and Redlich–Peterson isotherm models followed by Freundlich, which confirm the monolayer coverage of methylene blue molecules onto
P. oceanica fibres.
In this study, the performance of a pilot-scale membrane bioreactor (MBR) to treat real municipal wastewater was assessed at low temperatures (7 to 20°C) in Nordic regions. First, the effect of low ...temperatures on membrane fouling was evaluated by monitoring trans-membrane pressure. A significant membrane fouling was observed when the sludge temperature inside the MBR unit was below 10°C with a 75% permeability drop, thus indicating high deterioration of the membrane performance at low temperatures. Moreover, increasing values of sludge volume index (SVI) during low temperatures showed high deterioration of sludge settleability. As for the pollution removal, MBR achieved high performances primarily for pathogens and emerging micropollutants. The average log reductions of 1.82, 3.02, and 1.94 log units were achieved for norovirus GI, norovirus GII, and adenoviruses, respectively. Among the four trace organic compounds (TrOCs), the average removal efficiencies of bisoprolol, diclofenac and bisphenol A were 65%, 38%, and >97%, respectively. However, carbamazepine was not efficiently removed (‐89% to 28%). Regarding trace metals, an average removal of >80% was achieved for Cd, Pb, and V. For the rest of the metals, the removal capacities were between 30 and 60%.
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•Performance of a pilot-scale MBR was studied at low temperatures in Nordic region.•Substantial membrane fouling was observed at low temperatures (below 10°C).•About 75% of the permeability drop was observed due to fouling.•High removal rates were achieved for pathogens.•High removal rates for the emerging micropollutants were observed.
This book explores examples of the circular economy in action. Unlike other books that provide narrow perceptions of wide-ranging and highly interconnected paradigms, such as supply chains, ...recycling, businesses models and waste management, this book provides a comprehensive overview of the circular economy from various perspectives. Its unique insights into the approaches, methods and tools that enable people to make the transformation to a circular economy show how recent research, trends and attitudes have moved beyond the "call to arms" approach to a level of maturity that requires sound scientific thinking.
The removal of toxic metal, cadmium, by using adsorption into Algerian cork biomass was investigated. The biosorption process was studied with respect to contact time, particle size, pH and ...temperature. The results showed that equilibrium was reached within 1h. The used biosorbent gave the highest adsorption capacity at pH 6. The experimental isotherm data were analyzed and modeled. The maximum adsorption capacity, Langmuir’s qmax, improved from 9.65 to 14.77mg/g as the temperature increased from 20 to 40°C. The enthalpy ΔH° and entropy ΔS° values were respectively estimated at 110.47kJmol−1 and 0.3795kJK−1mol−1 for the process, which reflects the endothermic nature and the spontaneous feasibility of the present sorption system. Besides, the adsorption kinetics was found to follow the second-order model, suggesting therefore a possible chemisorption process.
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