Biological Water Treatment Research Articles

Optimum collection and concentration strategies of hydrobionts excess biomass in biological surface water purifying technologies

The analysis of perspective collection and concentration technologies of excess biomass in the technologies of wastewater and surface water biological treatment with the use of aquatic organisms has been carried out. The scheme of a life cycle of the aquatic organisms in wastewater and surface water treatment technologies has been proposed. The analysis of technological approaches for biomass collection of three types: aquatic plants and macroalgae; aquatic plants with a developed root system and microalgae of aquatic organisms has been carried out. A strategy for concentrating microalgae has been proposed. The high efficiency of the coagulation-flocculation gravitational thickening method of freshwater microalgae suspensions of the Microcystis aeruginosa species has been confirmed in laboratory conditions.

Steady-state operation of a biofilter coupled with photocatalytic control of bacterial bioaerosol emissions.

Bioaerosols are emitted during the biological treatment of water, soil, and air pollutants. The elimination of these pollutants has become a priority due to their detrimental effects on human health. Advanced oxidation technologies have been used to control bioaerosol emissions specially to improve indoor air quality. This investigation was focused on evaluating the biofiltration of ethyl acetate vapors in terms of removal efficiency and bioaerosol emission. Also, a continuous photocatalytic process to inactivate bioaerosols emitted from the biofilter was assessed as a post-treatment. The photocatalysis was developed with ZnO and TiO2 immobilized onto Poraver glass beads. Flow cytometry (FC) coupled with fluorochromes was used to characterize and quantify bioaerosol emissions in terms of live, dead, and injured cells. Ethyl acetate removal efficiencies were maintained in a steady state with values of 100% under 60-gm-3h-1 inlet load (IL). Biomass concentration in the biofilter reached values up to 228mgbiomassgperlite-1 at day 56 of operation, but the spontaneous occurrence of predatory mites diminished biomass concentration by 33%. Bioaerosols emitted during the steady-state operation of the biofilter were composed mainly by bacteria (~ 94%) and in a less extent of fungal spores (0.29-6%). The most efficient photocatalytic system comprised TiO2/Poraver with 78% inactivation of bioaerosols during the first 2h of the process, whereas the ZnO/Poraver system showed null activity (~ 0%) of inactivation. FC results show that the main mechanism of inactivation of TiO2/Poraver was cell death.

Effects of stabilizers on sustainability, activity and decolorization performance of Manganese Peroxidase enzyme produced by Phanerochaete chrysosporium

Manganese Peroxidase (MnP), is one of the most promising lignin depolymerization enzymes, which has been widely used for degradation purposes. Nevertheless, MnP tends to lose activity rapidly during its maintenance phase and degradation process, especially in the inevitable presence of hydrogen peroxide. This study aimed to improve MnP efficiency produced by Phanerochaete chrysosporium, via enhancing its sustainability. In this context, the effects of MnO2, Fe3O4, PEG, Veratryl Alcohol (VA), and DMSO as stabilizing agents on MnP activity were explored both in vivo and in vitro. During in vivo experiments, heterogeneous Fe3O4 was found to be the desirable choice to enhance MnP production, obtaining a maximum MnP activity of 2149 U/L, which was a 67 % boost over the stock configuration. Also, in vitro studies demonstrated a noticeable increase in the stability of the extracted MnP from 8 days up to 14, 23, 23, 25, and 26 days by the addition of MnO2, VA, Fe3O4, PEG, and DMSO stabilizers, respectively. The efficiency of stabilizers on degradation ability of MnP was also examined; optimum conversion of model dyes viz., AO7 and CV, were improved 36.17 and 126.51 % in response to stabilizers, respectively. The inclusion of stabilizers managed to improve sustainability, performance, and cost-effectiveness of the biological water treatment process.

Improvement of performances of the chemostat used for continuous biological water treatment with periodic controls

We investigate the benefit of operating the chemostat model with periodic controls for biological water decontamination. The first problem that we consider is to minimize the average output concentration of pollution under a constraint on the total quantity of water treated over the period. The second one consists in maximizing this quantity under a constraint on the average output concentration. We first give conditions on the growth characteristics of micro-organisms for which an improvement of the objective function (for the two problems) is possible, compared to the value at steady-state. We then provide the (global) optimal periodic control strategies for the first problem, and we then show a duality property both problems, which allows us to deduce the solutions of the second problem from the solutions of the first one. Results are illustrated on Monod’s, Haldane’s, Hill’s, and Contois’s kinetics.

Removal of emerging pharmaceutical pollutants: A systematic mapping study review

Abstract The presence of certain pharmaceutical compounds in ground and surface waters may constitute a serious environmental problem, even at low concentrations. The removal of these compounds is a trending research topic that implies a wide variety of disciplines. To provide clear insight into this field of research, a Systematic Mapping Study review (SMS) has been conducted. We investigated studies reported from 1993 to 2019 in ScienceDirect library. 4164 articles have been analyzed resulting in 172 primary relevant studies and revealing the treatment of 174 molecules. This paper aims to review the existing and recent trends in techniques for the removal of pharmaceuticals present in varied aqueous matrices and also presents a brief overview of the different classes of pharmaceutical compounds investigated. Findings of this study can help the scientists to identify potential techniques aiming to reduce the impact of pharmaceuticals present in wastewater discharge and into surface water bodies. It was revealed that, antibiotics and analgesics/anti-inflammatories are the most commonly investigated, since the highest risk is posed by these classes. The biological processes were found to be the most commonly used techniques in these field of research, and the diclofenac is the most extensively compounds examined. Recent advances in the field of the combination of AOPs with biological water treatment processes for the degradation of pharmaceuticals are discussed. Finally, advantage and limitations of methods used for the elimination of target compounds are addressed.

Constructed Wetland Parks: A Pathway to Sustainability For Cairo

Cairo is facing a vast number of urban, environmental and social challenges. It is constantly affecting the quality of life in the Egyptian Capital. Water resources are limited and one of the main challenges in Egypt, in addition to the Increasing population, Lack of green spaces, Air and Water pollution rate especially in Cairo. Using untraditional solutions in Egyptian cities now is a critical need, which will help in maximizing the benefits, decreasing projects and operations cost in this developing country. The Nile is the major water source in Egypt, according to recent studies this source is decreasing. UN and the Egyptian government published that Egypt has reached water poverty. Conservation and developing this resource is the cornerstone of academic researches and on the Egyptian government top priorities. Now in Egypt, the importance of recycling water in different methods increased. It is a basic need to cover water demands. Biological water treatment is one of the eco-friendly techniques for water treatment. Constructed wetland now is commonly used as an environmental tool in many countries. It achieves many benefits such as increasing biodiversity, habitats, water treatment and reduces air pollution. In the last decade, this technology was used in Egypt as a tool for water treatment in small-scale projects in The Northern lakes. The multifunction landscape is combining traditional landscape uses with human activities and production. This complexed harmony could achieve a balance between ecosystems with human impacts. Creating a wetland park as multifunction Landscape tool is a new approach in the world. Many countries have success stories in this field. This research will discuss international experiences in constructed wetland parks and local experiences in wetland areas, monitoring challenges and problems facing this technology and main potential elements that will lead to the success of this experiment in Egypt. Recognizing stakeholder complex needs, Ideas, and official plans for developing wetlands in Egypt. Finally, this research provides a framework and action plan to help in adapting the landscape market with this new approach, gives decision makers tools to achieve sustainability in future projects.

Biological Water Treatment by a Hybrid Fluidized‐Bed Bioreactor: Theoretical Study

AbstractA hybrid fluidized‐bed bioreactor for water purification was proposed and analyzed. It is a novel type of bioreactor characterized by hitherto unknown stationary and dynamic features. Steady‐state characteristics of this hybrid bioreactor with external liquid circulation are presented. A quantitative analysis of steady‐state properties of the bioreactor was performed with the aid of an original mathematical model developed for a double‐substrate aerobic microbiological process. A steady‐state analysis of aerobic processes characterized by different oxygen demand was performed. The effect of essential parameters was evaluated, including carbonaceous substrate concentration in the feed stream to the apparatus, aeration intensity, total residence time of a liquid in the bioreactor, and height of the bed of fine carrier particles.

A comparison of topologies in recirculating aquaculture systems using simulation and optimization

Recirculating aquaculture systems (RAS) are often designed using simplified steady-state mass balances, which fail to account for the complex dynamics that biological water treatment systems exhibit. Because of the very slow dynamics, experimental development is also difficult. We present a new, fast and robust Modelica implementation of a material balance-based dynamic simulator for fish growth, waste production and water treatment in recirculating aquaculture systems. This simulator is used together with an optimization routine based on a genetic algorithm to evaluate the performance of three different water treatment topologies, each for two fish species (Rainbow trout and Atlantic salmon) and each in both a semi-closed (no denitrification) and a fully recirculating version (with denitrification). Each case is furthermore evaluated at both saturated and supersaturated oxygen levels in the fish tank influent. The 24 cases are compared in terms of volume required to maintain an acceptable TAN concentration in the fish tank. The results indicate that the smallest volume is obtainable by introducing several bypass flows in the treatment system of a semi-closed RAS and that the gains can be significant. We also show that recycling already treated water back upstream in the treatment process degrades performance and that if one wishes to have a fully recirculating system with minimal water exchange, then the flows of oxygen, carbon and nitrogen must be carefully considered. For several of the cases, no optimum with denitrification could be found. We thus demonstrate that the best configuration and operation strategy for water treatment varies with the conditions imposed by the fish culture, illustrating the complexity of RAS plants and the importance of simulations, but also that computer-driven optimal design has the potential to increase the treatment efficiency of biofilters which could lead to cheaper plants with better water quality.

Peat swamp groundwater treatment: efficiency of mixed citrus peel and kernel activated carbon layer

One of the natural water resources is groundwater. Groundwater is another alternative to meet the increasing water demand in Malaysia. Then, the decrease in supplying raw groundwater which may due to depletion of groundwater and hence it is important to maintain the availability of water supply locally and even establish new water source such as from peat swamp to overcome future water crisis. Activated carbon is famous for its characteristic in eliminating various organic contaminants. In this investigation, low cost mixed activated carbon of food waste (citrus peel) and agricultural waste (palm kernel shell) are used as adsorbents in biological sand filter to treat peat swamp groundwater whereby the overall aim of study to evaluate the performance of mixed activated carbon layer of citrus peel and kernel in biological sand filter for peat swamp groundwater treatment. The mixed activated carbon with 1:1 ratio is filled into the biological sand filter. The efficiency of the mixed activated carbon layered biological sand water treatment system is evaluated using parameters pH, Turbidity, Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), Total Suspended Solids (TSS) and E. coli and removal of heavy metal ions of peat swamp groundwater. All these parameters follow the Standard Methods for Examination of Water and Wastewater 2005. The implementation of investigation improved the water quality of the peat swamp groundwater, the water treatment technology using combination of activated carbon and biosand filter, human living standards by providing safe and clean water supply.

Research of waste water biological treatment in filter grain loads

The biochemical processes occurring in sand filters loads of tertiary treatment of urban wastewater are investigated. The significance of those processes in reducing the overall biochemical and chemical oxygen demand in water purified by filters was established. The studies were conducted in natural conditions of the wastewater treatment plant in Krasnoyarsk using the installation for filters’ technological modeling. Equations for calculating and adjusting filtering parameters, taking into account biochemical processes, were obtained.

Endogenous respiration process analysis between aMBR and UV/O3-aMBR for polluted surface water treatment

Abstract The microbial endogenous respiration process is very important in biological water treatment processes. This study analyzed and compared the endogenous respiration process in an attached growth membrane bioreactor (aMBR) system and a UV/O3 integrated aMBR system (UV/O3-aMBR) in treating polluted surface water with CODMn around 10 mg/L. The endogenous respiration activity of heterotrophic microbes and autotrophic nitrifiers activity in both systems was analyzed and compared. Results show that heterotrophic bacteria and autotrophic nitrifiers enter endogenous respiration at 6 h aeration in an aMBR and 0 h in a UV/O3-aMBR system. Biomass amount on PVA-gel in aMBR was higher than in UV/O3-aMBR in terms of specific respiration rates SOURt, SOURH, and SOURA. Substrate remained on PVA-gel in the aMBR system, but no substrate remained on PVA-gel in the UV/O3-aMBR system. Higher species of microbes, including recoverable and irrecoverable components, existed in the aMBR system as compared to the UV/O3-aMBR system. The UV/O3-aMBR system could make full use of the advanced oxidation process (AOP) and biological process, leading to a higher treatment performance, and has the potential to mitigate total energy demand. Thus, the UV/O3-aMBR system can be used as a new technology for treating polluted surface water with the co-contribution of biological process and AOP treatment.

Modeling and research of the biological water treatment process considering the temperature regime

Household waste water contains mineral and organic pollution, while industrial varies both in composition and concentration, depending of the origin. Whatever type, all waste water required to be cleaned as it contains pollutants which far exceed the permissible concentration limits. Despite the large number of investigations of the corresponding processes, the actual task is to study the interaction of active sludge with pollution under the influence of external factors such as variable temperature, etc. Another important task is the prediction of process parameters waste water treatment based on the information with incomplete data at the design stage of the purification system. The automation of processes occurring in the reactor, in particular the use of bacteria with the optimal age, the creation of conditions for the maximum absorption capacity of active sludge, minimization of economic costs are integral components of modern systems.The mathematical model of aerobic waste water treatment is developed, which describes the processes occurring in the treatment plant taking into account the mutual influences of the characteristics of the process on the characteristics of the environment. The influence of external factors for the temperature calculation on the basis of the equation of thermal balance and the laws of thermodynamics is taken into account. The solution of the corresponding model problem using the m-function pdepe of the Matlab software is found. The influence of temperature of aqueous environment, concentration of oxygen on the absorbing capacity of active sludge is investigated. The dependence of bacterial activity from water temperature is shown.

ИССЛЕДОВАНИЕ ЭФФЕКТИВНОСТИ РЕАГЕНТНОЙ ОБРАБОТКИ ОСАДКОВ СТОЧНЫХ ВОД

Приведены результаты экспериментальных исследований кинетики осаждения избыточного активного ила, который составляет основную часть осадков сточных вод, в большом объеме образующихся после очистки воды на городских станциях биологической очистки. Образцы активного ила подвергали осаждению в присутствии химических реагентов с целью коагуляции и флокуляции твердых частиц, которые необходимо отделить от водной фазы. Для повышения эффективности разделения использовали в качестве коагулянтов сульфаты железа и алюминия, хлорид магния, а в качестве флокулянтов - крахмал и праестол. Продемонстрировано, что среди коагулянтов, способствующих разрушению гидратной оболочки избыточного активного ила, наилучший результат показал сульфат железа, в то время как применение хлорида магния было неэффективно. Установлена доза сернокислого железа, необходимая для коагуляции осадков. Полученные результаты можно использовать при рассмотрении путей дальнейшей переработки, размещения и утилизации осадков сточных вод. The paper presents results of experimental studies on kinetics of deposition of surplus activated sludge, which constitutes the main part of sewage sludge produced in bulk at municipal biological water treatment stations. Samples of activated sludge have been deposited in the presence of chemical reagents aiming at coagulating and flocculating solid particles followed by their separation from the aqueous phase. With a focus on increasing separation efficiency, iron(II) and aluminum sulfates along with magnesium chloride have been applied as coagulants, and starch and praestol - as flocculants. It has been demonstrated that among the coagulants that contribute to the destruction of the hydrated shell of the surplus activated sludge, ferrous sulfate shows the best result, while the use of magnesium chloride is ineffective. The effective dose of ferrous sulfate required for coagulating the sediments has been determined. The data obtained can be used when considering ways for further processing, disposal and utilization of the sewage sludge.

Production mechanism and characteristics of dissolved organic nitrogen derived from soluble microbial products (SMPs-DON) in a drinking water biological aerated filter

Abstract Dissolved organic nitrogen derived from soluble microbial products (SMPs-DON) generated during the drinking water biological treatment process poses a great threat to water supply safety due to the potential carcinogenic risk. To further study the production mechanism and characteristics of SMPs-DON in drinking water biological aerated filtration (BAF), Illumina MiSeq sequencing is applied to characterize the microbial community. In addition, an excitation–emission matrix combined with the parallel factor model (EEM-PARAFAC) and gel filtration chromatography (GFC) are used to analyze the component and molecular weight (MW) distribution of the SMPs-DON. Results showed that the production of SMPs-DON in drinking water BAF can be explained using Illumina MiSeq sequencing from the perspective of the microbial community. Also, according to the EEM-PARAFAC analysis, the fluorescence intensity scores of fulvic-like and humic-like substances were almost unchanged, whereas the scores of protein-like substances first increased and then decreased, which was consistent with the variation in the DON concentration. SMPs produced initially primarily consisted of macromolecules with MW >20 kDa, and then they were degraded and small molecular SMPs with MW <5 kDa accumulated. This study provides theoretical guidance and technical support for ensuring drinking water safety and reducing secondary pollution risks from drinking water biological treatment.

Transformation of minerals of a gellike sludge solid after the municipal waste water biological treatment under the bioextraction of heavy metals

Transformation of minerals of a gellike sludge solid after the municipal waste water biological treatment under the bioextraction of heavy metals

Using discrete and online ATP measurements to evaluate regrowth potential following ozonation and (non)biological drinking water treatment

Water utilities must control microbial regrowth in the distribution system to protect public health. In this study, an adenosine triphosphate (ATP)-based biomass production potential test using indigenous bacterial communities were used to evaluate regrowth potential following ozonation with either biofiltration (BF) or sustained chlorination (SCl2). Two full-scale water treatment plants with different upstream processes (i.e., WTP-BF: ozonation, coagulation/flocculation, biofiltration, UV irradiation, chlorination; and WTP-SCl2: ozonation, chlorination, coagulation/flocculation, filtration, chlorination) were compared. Characterization of indigenous bacteria using 16S rRNA gene sequencing, qPCR, and cellular ATP (cATP) showed microbial diversity changes across treatment, biomass sloughing from biofilters (effluent cATP = 30 ± 1 ng/L), and disinfection by chlorine (cATP < 1 ng/L). For both WTPs, 14-day cumulative biomass production (CBPt = ∑t=0tATP(t)×Δt) was highest for ozonated water samples (CBP14 = 1.2 × 103–3.0 × 103 d ngATP/L). CBP further increased with increasing ozone dose due to production of more biodegradable carbon. Growth promotion by carbon was confirmed from the consumption of ozonation byproducts (carboxylic acids, aldehydes) and the increase in CBP (9.5 × 102–2.9 × 103 d ngATP/L) after addition of 50–300 μgC/L acetate. Ozone followed by sustained chlorination (WTP-SCl2) effectively controlled biomass growth across the treatment process (CBP14 <10 d ngATP/L). In contrast, ozone followed by biofiltration (WTP-BF) reduced regrowth potential by 30% (biofilter influent CBP14 = 1.3 × 103 d ngATP/L; biofilter effluent CBP14 = 9.3 × 102 d ngATP/L). After adding chlorine to the biofilter effluent, CBP14 was reduced to <10 d ngATP/L. Lastly, online ATP measurements confirmed the discrete measurements and improved identification of the cATP peak and growth phases of indigenous bacteria.

Environmental Bacteria Involved in Manganese(II) Oxidation and Removal From Groundwater.

The presence of iron (Fe) and manganese (Mn) in groundwater is an important concern in populations that use it as source of drinking water. The ingestion of high concentrations of these metals may affect human health. In addition, these metals cause aesthetic and organoleptic problems that affect water quality and also induce corrosion in distribution networks, generating operational and system maintenance problems. Biological sand filter systems are widely used to remove Fe and Mn from groundwater since they are a cost-effective technology and minimize the use of chemical oxidants. In this work, the bacterial communities of two biological water treatment plants from Argentina, exposed to long term presence of Mn(II) and with a high Mn(II) removal efficiency, were characterized using 16S rRNA gene Illumina sequencing. Several selective media were used to culture Mn-oxidizing bacteria (MOB) and a large number of known MOB and several isolates that have never been reported before as MOB were cultivated. These bacteria were characterized to select those with the highest Mn(II) oxidation and biofilm formation capacities and also those that can oxidize Mn(II) at different environmental growth conditions. In addition, studies were performed to determine if the selected MOB were able to oxidize Mn(II) present in groundwater while immobilized on sand. This work allowed the isolation of several bacterial strains adequate to develop an inoculum applicable to improve Mn(II) removal efficiency of sand filter water treatment plants.

Degradation of ciprofloxacin by 185/254 nm vacuum ultraviolet: kinetics, mechanism and toxicology

Fluoroquinolone antibiotics (FQs) are highly resistant to conventional biological water treatment processes, thus, it is desirable to develop novel water treatment methods for eliminating FQs efficiently.

Application of unstructured kinetic models to predict microcystin biodegradation: Towards a practical approach for drinking water treatment

Biological drinking water treatment technologies offer a cost-effective and sustainable approach to mitigate microcystin (MC) toxins from harmful algal blooms. To effectively engineer these systems, an improved predictive understanding of the bacteria degrading these toxins is required. This study reports an initial comparison of several unstructured kinetic models to describe MC microbial metabolism by isolated degrading populations. Experimental data was acquired from the literature describing both MC removal and cell growth kinetics when MC was utilized as the primary carbon and energy source. A novel model-data calibration approach melding global single-objective, multi-objective, and Bayesian optimization in addition to a fully Bayesian approach to model selection and hypothesis testing were applied to identify and compare parameter and predictive uncertainties associated with each model structure. The results indicated that models incorporating mechanisms of enzyme-MC saturation, affinity, and cooperative binding interactions of a theoretical single, rate limiting reaction accurately and reliably predicted MC degradation and bacterial growth kinetics. Diverse growth characteristics were observed among MC degraders, including moderate to high maximum specific growth rates, very low to substantial affinities for MC, high yield of new biomass, and varying degrees of cooperative enzyme-MC binding. Model predictions suggest that low specific growth rates and MC removal rates of degraders are expected in practice, as MC concentrations in the environment are well below saturating levels for optimal growth. Overall, this study represents an initial step towards the development of a practical and comprehensive kinetic model to describe MC biodegradation in the environment.

Effect of the Electrodes Type on the Energy Efficiency of Microbial Fuel Cells

Traditional methods for wastewater treatment are associated with high energy consumption. This is why biological treatment of water is more appropriate at the moment. In our previous study, oxidation and reduction of pollutants have been proposed to be carried out in a microbial fuel cell (MFC) designed by our laboratory that simultaneously purifies wastewater from sulfide and nitrate ions and generates electricity. The experiments were carried out with two types of electrodes, graphite rods and paddling of activated carbon using a Fumapem® FFA-3-PK-75 (OH- form) membrane. The results show that the cell has higher energy output when using paddling of activated carbon as an electrode.