Classical Wastewater Treatment Research Articles

Tetracycline degradation for wastewater treatment based on ozone nanobubbles advanced oxidation processes (AOPs) – Focus on nanobubbles formation, degradation kinetics, mechanism and effects of water composition

Presence of pharmaceuticals, especially antibiotics, in industrial and domestic effluents causes serious damage to the environment. Classic wastewater treatment processes, in particular conventional biological treatment methods, are not sufficient to rapidly eliminate antibiotics. Typically, Advanced Oxidation Processes (AOPs) based on activation of hydrogen peroxide, ozone or persulfate for production of particular type of radical species or singlet oxygen are used. A one of cutting-edge technologies to increase effectiveness of AOPs based on ozone are nanobubbles based processes. Thus, this paper focuses on utilization of ozone in the form of nanobubbles for degradation of tetracycline (TC). The effects of several reaction parameters, such as antibiotic concentration, ozone intake, pH, presence of salts, were investigated. This study revealed that the presence of ozone nanobubbles had a substantial positive impact on the degradation of TC. This improvement may be attributed to the enhanced mass transfer and the production of reactive radicals that occur during the collapse of the nanobubbles. Identification of radical species revealed a significant contribution of hydroxyl radicals in the degradation of the antibiotic. AOP process based on O3 nanobubbles was most (•OH) and superoxide (O2–) effective with 100 % degradation efficiency of 100 mg/L TC within 20 min at 8 mg/L concentration of ozone. Based on identified by LC-MS intermediates a degradation mechanism has been described. Degradation of TC and intermediates transformations included methylation, hydroxylation, ring-opening steps as well as cleavage of C-N bonds. This research introduces a novel technique combining nanobubbles with advanced oxidation processes (AOPs), which is anticipated to provide enhanced efficiency and environmental sustainability.

The role of membrane filtration in wastewater treatment

AbstractWater is vital for the sustainable growth of human communities. Due to the greatest population and significant economic development, demands on water and purification have significantly risen. Classical wastewater treatment procedures have made some progress over the years in purifying effluents for disposal, but they fall lacking in the way they deeply control emerging harmful substances. The potential to reuse treated wastewater for home, agricultural, and industrial needs depends on breakthroughs in purifying technologies. One of the most recent breakthroughs to be implemented effectively in reducing contaminants to desirable levels is membrane technology. Nanofiltration, microfiltration, reverse osmosis, ultrafiltration, and membrane bioreactors are examples of widely utilized membrane processes depending on features such as size or charge. Over traditional treatment, membrane technology offers various benefits. This review article discusses a number of membrane‐related topics, including membrane categorizing, application in various fields, benefits, and drawbacks. Furthermore, offers an outlook of the filtering membranes that will be used in the future. Smart membranes have gained interest because of their tunable permeability and selectivity characteristics. Technological advancements in the media that are utilized in activated growth membrane bioreactors. Modified interfacial polymerization approaches have been investigated in addition to adsorptive ultrafiltration mixed matrix membranes to enhance the performance of the polyamide thin‐film composite and thin‐film nanocomposite membranes.

Nitrogen use efficiency of microalgae application in wheat compared to mineral fertilizer

AbstractBackgroundWastewater from sewage treatment plants contains high levels of nutrients, which can be used for plant nutrition. Classical wastewater treatment plants use complex microbial consortia of autotrophic and heterotrophic microorganisms for biological wastewater treatment. Certain autotrophic microalgae (e.g., species of the genera Chlorella, Scenedesmus, and Pediastrum) accumulate nutrients from wastewater very effectively.AimsWe investigated the potential of microalgae biomass obtained from a prototype wastewater treatment plant as a source of nutrients for crops, focusing on nitrogen.MethodsWe provided wheat plants with different levels of algae biomass equivalent to 60, 120, and 180 kg N per hectare or with mineral fertilizer (N, P, and K) equivalent to the amounts contained in the algal biomass. Physiological and phenotypic traits were measured during growth, including vegetation indices, photosynthetic performance, growth, and nitrogen use efficiency (NUE). In addition, the adundances of Bacteria, Archaea and fungi and genes of ammonium oxidizing Bacteria and Archaea were determined in the rhizosphere of differently fertilized plants.ResultsMicroalgal application at fertilizer levels of 120 and 180 kg N ha–1 showed significantly improved physiological performance, growth, yield and nutrient uptake compared to the unfertilized control. Nevertheless, their yields and NUE were lower than with the application of equal amounts of mineral fertilization, while the adundance of rhizosphere microbes and ammonia‐oxidizing microorganisms were not significantly affected.ConclusionsMicroalgae from wastewater treatments form a suitable source of organic fertilizer for wheat plants with only moderate reductions in N use efficiency compared to mineral fertilizer.

Dimethyl phthalate removal from aqueous system using a photocatalytic membrane reactor with suspended photocatalyst

Dimethyl phthalate is low molecular weight phthalate used on a wide scale within industry for manufacture of plastics, solvents, adhesives, lubricants, coatings and due to its poor biodegradability is not removed by classic wastewater treatment processes. It was proved that it affects the endocrine system, presenting carcinogenic, teratogenic and mutagenic effects on upon living organisms. Therefore, there is a need for more advanced treatment methods such as advanced oxidation processes for dimethyl phthalate removal from aqueous systems. A hybrid process consisting from photo catalysis and membrane based processes was investigated and the optimum parameters for dimethyl phthalate removal were established. In respect to photocatalytic process the influence of photo catalyst dose, pH, irradiation time were studied and process kinetics were set up using a synthetic dimethyl phthalate solution. In order to recover and reuse the photocatalyst a membrane process was used and optimum working pressure was determined. In the case of real wastewater matrix the addition of hydrogen peroxide was needed, in the photocatalytic stage, in order to improve process efficiency. Four treatment cycles, using real wastewater spiked with dimethyl phthalate, were performed with the reuse of photo catalyst proving that the use of photocatalytic membrane reactor with suspended photo catalyst represents a promising method for phthalates removal from aqueous systems.

“Patenting of Classic Wastewater Treatment System with Naturally Occurring Organic Materials in the Niger Delta Region of Nigeria”

The Classic wastewater treatment system (engineered sewage treatment system) was developed and deployed to treat domestic waste (human fasces and urine) water for re-use. Naturally occurring organic materials were used in the treatment process, where 40% of these treatment materials are considered as waste in itself. Effluent from the treatment system was analyzed with physico-chemical and microbial parameters within stipulated limits of WHO/FMENV for safe water use. The removal efficiency of E.Coli, fecal coliform, total coliform, streptococcus and phosphorus from the effluent ranged between 90 to 99% which shows the effectiveness of the treatment system in sewage treatment.

Removal of emerging contaminants from wastewater using advanced treatments. A review

The rise of emerging contaminants in waters challenges the scientific community and water treatment stakeholders to design remediation techniques that are simple, practical, inexpensive, effective, and environmentally friendly. Emerging contaminants include antibiotics, hormones, illicit drugs, endocrine disruptors, cosmetics, personal care products, pesticides, surfactants, industrial products, microplastics, nanoparticles, and nanomaterials. Removing those contaminants is not easy because classical wastewater treatment systems are not designed to handle emerging contaminants, and contaminants often occur as traces in complex organo-mineral mixtures. Here, we review advanced treatments for the removal of emerging contaminants in wastewater, with focus on adsorption-oriented processes using non-conventional adsorbents such as cyclodextrin polymers, metal–organic frameworks, molecularly imprinted polymers, chitosan, and nanocellulose. We describe biological-based technologies for the degradation and removal of emerging contaminants. Then, we present advanced oxidation processes as the most promising strategies because of their simplicity and efficiency.

Regulation of Hydrogen Peroxide Dosage in a Heterogeneous Photo-Fenton Process

In this work, a classical linear control approach for the peroxide (H2O2) dosage in a photo-Fenton process is presented as a suitable solution for improving the efficiency in the treatment of recalcitrant organic compounds that cannot be degraded by classical wastewater treatment processes like anaerobic digestion. Experiments were carried out to degrade Lignin, Melanoidin, and Gallic acid, which are typical recalcitrant organic compounds present in some kinds of effluents such as vinasses from the Tequila and Cachaça industries. Experiments were carried in Open-Loop mode for obtaining the degradation model for the three compounds in the form of a Transfer Function, and in Closed-Loop mode for controlling the concentration of each compound. First-order Transfer Functions were obtained using the reaction curve method, and then, based on these models, the parameters of Proportional Integral controllers were calculated using the direct synthesis method. In the Closed-Loop experiments, the Total Organic Carbon removal was 39% for lignin, 7% for melanoidin, and 29% for Gallic acid, which were greater than those obtained in the Open-Loop experiments.

Photocatalytic Decomposition of Dye polluted Wastewater Using Titanium Dioxide and Graphitic Carbon Nitride

Advanced oxidation process (AOPs) is an alternative to the classical wastewater treatment methods which are environmentally friendly, producing harmless end-products such as CO2 and H2O2. APOs are in-situ treatment processes characterized by the generation of highly reactive intermediates (OH radicals) which can oxidize the target organic pollutants. This paper studied the operational parameters influencing the photocatalytic degradation rate of methylene blue in dye polluted wastewater treatment. These parameters are initial dye concentration, catalyst concentration, H2O2 volume. The catalysts used were titanium dioxide (TiO2) and supported Graphene (g-C3N4). Hydrogen peroxide (H2O2) was used in all experimental work to increase the efficiency of the UV / TiO2 process and supported Graphene (g-C3N4). The experiments of UV lamp revealed that the best degradation is at 5 ppm initial dye concentration, 0.5 g from g-C3N4 and 5 ml/dm3 H2O2 with efficiency 54.8 % at 180 minutes by using solar UV. The experiments of solar UV illustrated that the best degradation is at 15 ppm initial dye concentration, 0.5 g from g-C3N4 and 5 ml H2O2 with efficiency 80.64 % at 120 minutes. It’s confirmed that using the solar unit is the best choice for the photocatalytic oxidation process.

МЕТОДИ РЕГЕНЕРАЦІЇ МЕМБРАН У СФЕРІ ОЧИЩЕННЯ СТІЧНОЇ ВОДИ

Membrane technologies have become widespread in recent years and have a big chance of eventually replacing the classic wastewater treatment system that no longer meets the needs of the modern world. The method of membrane separation, combined with previous biological treatment, is characterized by a high degree of purification, stability of the system irrespective of load fluctuations, and low environmental impact. However, there are several disadvantages among all the positives, the main ones being the high cost and the membrane fouling. These problems are interrelated, so if you solve the problem of membrane fouling, then the high cost will pay off over time. Hundreds of scientific studies in this field have succeeded in minimizing the negative effects of membrane fouling and clogging/sludging, which have long been the main limiting factors for widespread introduction of membrane technologies. To reduce the limiting effect of fouling on the membrane, a number of indicators can be adjusted, including hydrodynamic mode, peculiarities of membrane operation and purification, quality of feeding water and concentration of impurities, and characteristics and material of the membranes. Although the techniques for minimizing fowling have been developed in different directions, when developing the right approach, they can be combined with a much better effect, for example, combined membrane purification, including backwashing, relaxation, and chemical periodic treatment. In the last decade, membrane technologies have become widespread, and their introduction into existing wastewater treatment plants continues to grow in various countries all over the world, including Sweden, China, Singapore, the United States, Korea, and others. Provided effective inhibition of membrane fouling, such systems have the potential to become the main wastewater treatment plants. In the review article the basic methods of membranes purification – from classical to the recent developments – are systematized.

Dinitrodiazophenol industrial wastewater treatment by a sequential ozone Fenton process.

The ozonation process is efficient in degrading aromatic substances and substances with unsaturated bonds, but cannot effectively destroy small-molecule organic compounds, which accumulate. Likewise, the Fenton process is a classic wastewater treatment method, but requires strict pH control and produces secondary pollution when the concentration of organic substances is high. In this study, we applied a 1stO3-2ndFenton sequential process to treat diazodinitrophenol (DDNP) industrial wastewater and provide suitable reaction conditions for Fenton process. For the 1stOzone process, organics removal increased as O3 dosage increased. At optimized operation, the 1stO3 process provided an acidic effluent (pH = 3) and reduced the organics concentration to a level suitable for the 2ndFenton process. Benzene ring substances as well as nitro group and diazo group compounds were greatly degraded in the 1stO3 process and were further mineralized in the 2ndFenton process. Additionally, the biodegradability of DDNP industrial wastewater was greatly improved. This is the first reported time that ozonation and the Fenton process have been integrated sequentially to treat an explosive production wastewater. The study provides a feasible chemical oxidation method for treating DDNP industrial wastewater by simply combining two classic treatment processes.

Research of sewage intake of small settlements in dry weather

Introduction. Attempts to apply classical wastewater treatment technologies to small volumes are often impossible due to the high irregularity of wastewater inflows, and fundamental fluctuations in the composition of wastewaters, which are very diverse in comparison with medium and large cities. At three sites located in the Leningrad Region, full-scale measurements of wastewater discharges from settlements with a population of 1000 people and an industrial enterprise were carried out in order to determine the irregularity coefficients of wastewater during the dry season. The irregularity coefficients used in the design practice for such objects differ greatly in their values, as determined in the process of analyzing the literature data, which, when designing head sewage treatment plants, can lead to significant errors in calculations. Materials and methods. Measurement of a daily consumption of sewage flowmeters counters, elimination of improbable values, definition of consumption in dry weather, comparison of these various objects. Results. Mathematical dependences are proposed for describing fluctuations in the daily coefficient of irregularity of waste during the year. It was proposed to describe the weekly fluctuation of expenses with the help of the weekly coefficient of non-uniformity and its values were determined for the studied objects. A method has been developed for determining estimated costs for small objects with a population of 1000 people. Conclusions. The developed technique allows to predict the size of coefficient of daily unevenness within a year in dry weather for small settlements with number of inhabitants of 1000 people and a small share of production drains. It is possible to recommend values of coefficients of week unevenness.

The Environmental Biorefinery: Using Microalgae to Remediate Wastewater, a Win-Win Paradigm

Microalgae have been shown to be a source of multiple bio-based products ranging from high value molecules to commodities. Along with their potential to produce a large variety of products, microalgae can also be used for the depollution of wastewaters of different origins (urban, industrial, and agricultural). This paper is focused on the importance of harnessing the bioremediation capacity of microalgae to treat wastewaters in order to develop the microalgae industry (especially the microalgae biofuel industry) and to find other alternatives to the classic wastewater treatment processes. The current research on the potential of microalgae to treat a specific wastewater or a targeted pollutant is reviewed and discussed. Then, both strategies of selecting the best microalgae strain to treat a specific wastewater or pollutant and using a natural or an artificial consortium to perform the treatment will be detailed. The process options for treating wastewaters using microalgae will be discussed up to the final valorization of the biomass. The last part is dedicated to the challenges which research need to address in order to develop the potential of microalgae to treat wastewaters.

Integrating a microbial electrochemical system into a classical wastewater treatment configuration for removing nitrogen from low COD effluents

We investigated the adaptation of a classical oxic–anoxic chamber configuration to a microbial electrochemical system in order to remove both nitrogen and organic matter from low COD effluents.

Occurrence, fate and removal of endocrine disrupting compounds (EDCs) in Turkish wastewater treatment plants

Endocrine disrupting compounds, EDCs, are somewhat recently recognized pollutants which are often classed within ‘emerging micropollutants’ in the environment jargon. These compounds are known to interfere with the delicate balance of the endocrine system of animals and man, causing variety of undesirable outcomes. Their sources in natural waters are the domestic and industrial effluents. The main cause of concern with EDCs is their tendency to accumulate in fish causing gender shifts and reduced fecundity. Moreover, their possible interference with the water cycle and concurrent effects on the human endocrine system has been implicated. Increased usage of medication and surfactants in the household; pesticides in agriculture have all add up to the inventory of EDCs in the aqueous systems.Current view in combating EDCs in water cycle is the multi barrier approach. In this concept EDCs are tried to be controlled in effluents as well as in potable drinking waters. Therefore, knowledge on their elimination in classical wastewater treatment plants is vital for establishing sustainable strategies for the future.Five different EDCs were selected as model compounds in this study; two natural hormones, estrone and progesterone, which are constantly discharged by humans; carbamazepine, diltiazem and acetaminophen are pharmaceuticals which are widely used by the community. The 24h composite samples were analyzed in influents and effluents of 7 full scale biological treatment plants of various modifications of activated sludge process, including one MBR plant. One striking finding was the removals obtained in conventional plants, which were far exceeding those obtained in the mid-scale or lab-scale MBR plants. Carbamazepine and diltiazem, two hydrophobic compounds, were found to sorb onto CAS sludge whereas not onto the MBR sludge.

Study of the sludge reduction in an oxic-settling-anaerobic activated sludge process based on UNITANK.

An oxic-settling-anaerobic process (OSA) can effectively reduce sludge production, but most of the research studies on the OSA process have been either under laboratory test conditions or based on synthetic wastewater, which cannot fully reflect the performance and sludge reduction efficiency in existing OSA process. Thus, aiming at examining the sludge reduction efficiency and the stability of the OSA process, UNITANK and UNITANK-OSA processes were performed in a 120 m(3)/d pilot-scale system using actual sewage. The results indicate that UNITANK-OSA achieved a 48% reduction of the sludge compared to the reduction due to UNITANK, not considering the accumulation of the effluent-suspended solids. The effluent quality was not found to change significantly, except that the total phosphorus concentration increased slightly. The extracellular polymeric substances metal floc theory may, to some extent, explain this reduction in this study. The OSA process could be used to reform the classic wastewater treatment process to get lower sludge mass.

Comparative pilot study of the performances of two constructed wetland wastewater treatment hybrid systems

For small settlements sanitation, constructed wetland systems offer a suitable social economic alternative to the classic wastewater treatment plants. In order to study the treatment mechanisms occurring in the soil–plant system, we set up a small-scale pilot wastewater treatment plant composed by a settler/digester followed by two trains combining two different types of subsurface flow constructed wetlands called ‘hybrid systems’. The first train represents a combination of a vertical flow reed (Phragmites australis) bed followed by a horizontal bed, planted with Typha, whereas in the second one, the combination is reversed.The hybrid systems are fed intermittently with a hydraulic load of 0.2 m per day given in two sequences of one hour separated by a six-hour rest period. We followed the quality of the effluent at the outlet of the beds. The two hybrid systems present satisfactory performances: yields higher than 90% in organic matter removal are registered.For the first system we could obtain a substantial nitrification but uncompleted denitrification whereas for the second system we observed that the total nitrogen (NTK) reduction was achieved by denitrification and nitrification remains almost complete. The pathogenic bacteria abatement is satisfactory for the two systems but more remarkable for the second (2 u log).

Identification of ionic liquid breakdown products in an advanced oxidation system

Commonly used alkylimidazolium ionic liquids are poorly to negligibly biodegradable, and some are toxic, with the potential to poison typical biological test systems. Therefore, when ionic liquids are present in technological wastewaters they could break through classical wastewater treatment systems into natural waters and become potentially persistent pollutants. A recent study investigating different advanced oxidation processes found that the H 2O 2/UV system degraded dissolved imidazolium ionic liquids with the greatest efficiency. In the present study, high performance liquid chromatography was coupled with electrospray mass spectrometry to separate, analyse and identify degradation products following the treatment of ionic liquid solutions with H 2O 2 in the presence of UV irradiation. It was found that hydroxylation in short-chain entities occurred mainly within the ring moiety, whereas in the case of longer alkylated cations, oxidation of the alkyl chain yielded several products. The potential transformation products were identified structurally by MS/MS analysis and are discussed in the light of their putative toxicity and biodegradability.

Energy- and CO2-reduction potentials by anaerobic treatment of wastewater and organic kitchen wastes in consideration of different climatic conditions

The classical municipal wastewater treatment in Germany consists of an aerobic carbon and nitrogen elimination and mostly an anaerobic sludge treatment. Organic kitchen wastes from separate waste collection as well as yard wastes are converted mostly in composting plants to soil conditioner. With these conventional types of treatment, the energy potential in waste and wastewater is lost due to aerobic material conversion. In this article three scenarios for the treatment of municipal wastewater and waste are compared on the subject of energy efficiency and useable potential: Sc1. the classical wastewater treatment and the composting of the organic waste fraction, Sc2. the anaerobic treatment of wastewater combined with deammonification and the digestion of the organic waste fraction, and Sc3. a mutual anaerobic treatment of wastewater and waste as co-digestion with deammonification. The calculation of energy and CO2-balance considers different climatic conditions. In case of using anaerobic treatment, not only the energy balance will be positive, also the CO2-balance is improved by the substitution of fossil fuels with generated biogas.

Sulphonated aromatic pollutants. Limits of microbial degradability and potential of phytoremediation.

Many synthetic sulphonated aromatic compounds are used as starting material to produce dyes and pigments, or are released as by-products in the effluents of the textile and dye industry. A large number of these chemicals are poorly biodegradable and cannot be eliminated by classical wastewater treatment plants. To limit the impact of these pollutants on the environment, new processes, based on the use of higher plants (constructed wetlands or hydroponic systems), are under development. Detergents and surfactants are essential for both industrial and domestic applications, the most important family being the alkylbenzene sulphonates. Originally, the alkyl side chains were branched and thus recalcitrant to biodegradation. Therefore, they have been replaced by linear alkylbenzene sulphonates. Although more acceptable, present formulations still have adverse environmental and toxic effects. In this context, phytoremediation appears to be a promising approach to remove these compounds from contaminated soils and waters.

Reversibility of fouling formed in activated sludge filtration

This paper investigates the reversibility of membrane fouling by activated sludge in a membrane bioreactor equipped with a 0.1 μm pore ceramic membrane. The membrane was submitted to a series of tests in which the permeate flux, the transmembrane pressure (TMP) or the circulation velocity were successively varied in cycles by step increments or decreases. When the permeate flux is set below the critical flux, the TMP remains stable and fouling is reversible. On the contrary, when the critical flux is exceeded, the TMP increases and does not stabilize, as in dead-end filtration. The fouling formed is partly irreversible when the flux is lowered again. When the TMP is first increased up to 400 kPa and then decreased back at constant velocity, no hysteresis is found on the flux–TMP graph, showing that fouling is reversible in this case. Velocity cycles were performed by first lowering the velocity from 5 to 1 m/s and raising it again to 5 m/s. In this case again, the fouling induced by reducing the velocity was found to be reversible. However, when the same pressure and velocity cycle tests were performed with activated sludge collected in the aeration tank of a classical wastewater treatment plant, fouling was found to be partly irreversible, showing that the cake formed in the absence of shearing is much more cohesive. In the final part of the paper, we tested a hydrodynamic method of fouling control consisting in alternating short periods of filtration (1–4 s) and short periods of washing (1 or 2 s) at low TMP and high velocity. This method yielded to a 20% permeate flux increase with a 10% reduction in hydraulic energy consumption for classical plant activated sludge.