Tertiary Water Treatment Research Articles

Advanced oxidation processes: a supplementary treatment option for recalcitrant organic pollutants in Abattoir wastewater

Animal production and meat processing generate large amounts of waste. Large amount of water containing substantial quantities of biodegradable organic matter are produced as a result of the slaughtering of animals and the routine washing of leftover particles in the abattoir. Blood, fats, oil, and grease, undigested food, suspended materials, etc. are a few examples of the materials that typically contributed organic load to these effluents. Thus, regulatory agencies prohibit the direct discharge of the effluents and solid abattoir wastes into the environment. This is because these wastes are potential pollutants and can increase harmful ecological hazards, therefore, treatment is required before discharge into environment. The advanced oxidation processes (AOPs), a tertiary water treatment method is based on the production of hydroxyl radicals, which brings about its non-selective reaction with water contaminants, allowing mineralization of contaminants and converting them into CO2 and water. AOPs could be applied to oxidize pollutants in abattoir wastewater (AWW), and may be used as a supplementary treatment system. A combined process involving the physical and biological treatments, and AOPs may be used as an alternate form of treatment with the potential for greater effectiveness and dependability. However, the properties of the wastewater, treatment time, influent concentration, type of treatment, and the best treatment technique currently available to comply with the standards will all have a significant impact on treatment efficiencies of AWW.

Water and dialysis fluid purity for contemporary hemodialysis.

The purity of water and dialysis fluids is of utmost importance in ensuring the safe and effective administration of hemodialysis treatment to patients with chronic kidney disease. It is crucial to enforce compliance with international standards for dialysis water and fluids, as this is mandatory in reducing chemical hazards, mitigating the adverse effects of bioincompatibility resulting from contaminated water and ultimately enhancing long-term patient outcomes. Within this comprehensive review, we highlight the presence of water contaminants and thoroughly assess the existing international standards for dialysis water and fluids, spanning from pure to ultrapure. Additionally, we delve into the fundamental components of water purification and present a comprehensive range of water treatment options, encompassing pre-treatment, primary treatment (reverse osmosis), and tertiary water treatment. Furthermore, we outline recommended monitoring and maintenance procedures, ensuring the consistent delivery of high-quality water and dialysis fluids at the point of care. WATER PURIFICATION AND MONITORING SUSTAINABILITY AND FUTURE CHALLENGES: Importantly, we raise concerns regarding the sustainability and conservation of water resources in hemodialysis treatment. It is imperative that these concerns be addressed in the future to avert the potential shortage of this essential resource. In conclusion, the contemporary landscape of hemodialysis conditions has engendered an urgent necessity for advanced water treatment systems and optimized delivery of dialysis fluids. This review serves as a comprehensive update on the latest technological advancements aimed at meeting these critical demands. Dialysis water and fluids must adhere to increasingly stringent purity constraints, encompassing both biochemical and microbiological perspectives.

Biochar integrated reactive filtration of wastewater for P removal and recovery, micropollutant catalytic oxidation, and negative CO2 e: Process operation and mechanism.

Biochar (BC) use in water treatment is a promising approach that can simultaneously help address societal needs of clean water, food security, and climate change mitigation. However, novel BC water treatment technology approaches require operational testing in field pilot-scale scenarios to advance their technology readiness assessment. Therefore, the objective of this study is to evaluate the system performance of BC integrated into hydrous ferric oxide reactive filtration (Fe-BC-RF) with and without catalytic ozonation (CatOx) process in laboratory and field pilot-scale scenarios. For this investigation, Fe-BC-RF and Fe-CatOx-BC-RF pilot-scale trials were conducted on synthetic lake water variants and at three municipal water resource recovery facilities (WRRFs) at process flows of 0.05 and 0.6L/s, respectively. Three native and two iron-modified BCs were used in these studies. The commercially available reactive filtration process (Fe-RF without BC) had 96%-98% total phosphorus (TP) removal from 0.075- and 0.22-mg/L TP, as orthophosphate process influent in these trials. With BC integration, phosphorus removal yielded 94%-98% with the same process-influent conditions. In WRRF field pilot-scale studies, the Fe-CatOx-BC-RF process removed 84%-99% of influent total phosphorus concentrations that varied from 0.12 to 8.1 mg/L. Nutrient analysis on BC showed that the recovered BC used in the pilot-scale studies had an increase in TP from its native concentration, with the Fe-amended BC showing better P recovery at 110% than its unmodified state, which was 16%. Lastly, the field WRRF Fe-CatOx-BC-RF process studies showed successful destructive removals at >90% for more than 20 detected micropollutants, thus addressing a critical human health and environmental water quality concern. The research demonstrated that integration of BC into Fe-CatOx-RF for micropollutant removal, disinfection, and nutrient recovery is an encouraging tertiary water treatment technology that can address sustainable phosphorus recycling needs and the potential for carbon-negative operation. PRACTITIONER POINTS: A pilot-scale hydrous ferric oxide reactive sand filtration process integrating biochar injection typically yields >90% total phosphorus removal to ultralow levels. Biochar, modified with iron, recovers phosphorus from wastewater, creating a P/N nutrient upcycled soil amendment. Addition of ozone to the process stream enables biochar-iron-ozone catalytic oxidation demonstrating typically excellent (>90%) micropollutant destructive removals for the compounds tested. A companion paper to this work explores life cycle assessment (LCA) and techno-economic analysis (TEA) to explore biochar water treatment integrated reactive filtration impacts, costs, and readiness. Biochar use can aid in long-term carbon sequestration by reducing the carbon footprint of advanced water treatment in a dose-dependent manner, including enabling an overall carbon-negative process.

Comparison of antibiotic-resistant Escherichia coli and extra-intestinal pathogenic E. coli from main river basins under different levels of the sewer system development

Antimicrobial-resistant Escherichia coli in the aquatic environments is considered a strong indicator of sewage or animal waste contamination and antibiotic pollution. Sewer construction and wastewater treatment plant (WWTP) infrastructure may serve as concentrated point sources of contamination of antibiotic-resistant bacteria and antibiotic resistance genes. In this study, we focused on the distribution of antimicrobial-resistant E. coli in two rivers with large drainage areas and different urbanisation levels. E. coli from Kaoping River with drainage mainly from livestock farming had higher resistance to antibiotics (e.g. penicillins, tetracyclines, phenicols, aminoglycosides, and sulpha drugs) and presented more positive detection of antibiotic-resistance genes (e.g. ampC, blaTEM, tetA, and cmlA1) than that from Tamsui River. In Kaoping River with a lower percentage of sewer construction nearby (0–30%) in contrast to a higher percentage of sewer construction (55–92%) in Tamsui River, antimicrobial-resistant E. coli distribution was related to livestock farming waste. In Tamsui River, antimicrobial resistant E. coli isolates were found more frequently in the downstream drainage area of WWTPs with secondary water treatment than that of WWTPs with tertiary water treatment. The Enterobacterial Repetitive Intergenic Consensus (ERIC) PCR showed that the fingerprinting group was significantly related to the sampling site (p < 0.01) and sampling date (p < 0.05). By utilising ERIC-PCR in conjunction with antibiotic susceptibility and antibiotic-resistance gene detection, the relationship among different strains of E. coli could be elucidated. Furthermore, we identified the presence of six extra-intestinal pathogenic E. coli isolates and antibiotic-resistant E. coli isolates near drinking water sources, posing a potential risk to public health through community transmission. In conclusion, this study identified environmental factors related to antibiotic-resistant bacteria and antibiotic-resistance gene contamination in rivers during urban development. The results facilitate the understanding of specific management of different waste streams across different urban areas. Periodic surveillance of the effects of WWTPs and livestock waste containing antibiotic-resistant bacteria and antibiotic-resistance genes on river contamination is necessary.

Enhanced degradation of emerging contaminants by percarbonate/Fe(II)-ZVI process: case study with nizatidine.

Pharmaceuticals have recently emerged as a significant environmental concern due to the growth of population, expansion of industry, and the shift in modern lifestyles. Herein, we present a Fe(II)/percarbonate (SPC) process with dramatically enhanced efficiency by the introduction of zerovalent iron (ZVI). After the addition of ZVI, the removal rate of nizatidine (NZTD) went up from 71.7 to 84.2%. The removal rate of NZTD decreases with rising pH and speeds up with increasing temperature. It was found that under the condition of pH = 7 and T = 25°C, the molar ratio of the optimal concentration of NZTD degradation in the system was [NZTD]0:[SPC]0:[Fe(II)]0:[ZVI]0 = 1:8:24:16, with a degradation rate of 99.8%. At the same time, target pollutants can also be successfully eliminated from actual water bodies. Moreover, we test for toxicity using luminescent bacteria, and the results demonstrate that the system is capable of effectively decreasing the toxicity of NZTD. The research findings can contribute to the clarification of the migration and transformation law of NZTD in the oxidation process, thereby providing a scientific basis and technical support for the removal of NZTD in the tertiary water treatment for a water source.

A non-doped microporous titanosilicate for bimodal adsorption-photocatalysis based removal of organic water pollutants

Access to clean drinking water is limited for millions around the world and lead to dire health and economic ramifications, particularly in developing nations. This study explores a recyclable, low-cost, non-doped, microporous titanosilicate for effective removal of organic water pollutants. Rhodamine B was utilized as a modal pollutant to explore and optimize the activity of the titanosilicate, which evidently occurred via an adsorption and subsequent photocatalytic degradation based bimodal mechanism. The novel titanosilicate has high surface area (SBET of 468 m2/g), is microporous (∼1.3 nm pore diameter), achieved via a surfactant templating technique. Its’ physicochemical properties were characterised using FTIR, Raman, BET, SEM, PXRD and XPS. The photocatalytic activity of the material was studied under a solar simulator via time dependent UV–vis absorption measurements. The material showed 97% removal of Rhodamine B (5 mg/L) within 3 h, and outperformed nanosized titanium dioxide (anatase:rutile 4:1), the most conventionally used photocatalyst in tertiary water treatment. Interestingly, the titanosilicate displayed a dual mechanism of pollutant removal: an initial rapid removal of 59% due to adsorption during a 30 min equilibrating step in the dark, followed by near complete removal within 3 h. Additionally, a >90% efficiency of Rhodamine B removal by the titanosilicate catalyst was achieved consistently throughout 4 cycles, demonstrating its ability for regeneration and reusability. Such activity has not been previously reported in non-doped or non-composite titanosilicates, and opens up pathways to efficient, low-cost water treatment materials, consisting only of environmentally benign raw materials and synthetic procedures.

A multidimensional study of wastewater treatment

Water usage generates wastewater, which must be collected and treated properly before being returned into the hydrological cycle for reasons of sustainable development and water supply.The content and volume of waste water generated are determined by a range of elements, as most of them are the waste of households, industries and so on. It also dictates the necessary treatment methods. Waste water treatment facilities function at a crucial stage in the water cycle, assisting nature in protecting water from contamination. Treatment methods can be categorized into four segments: preliminary, primary, secondary and tertiary wastewater treatment. Screening and grit removal are ordinary parts of preliminary wastewater treatment. Basically, it prepares wastewater for further treatment. Although the primary purpose of wastewater treatment is to separate easily-removable suspended particles and BOD, wastewater components that occur as dissolved solids or settleable wastewater solids may also be eliminated here using a septic tank, the Imhoff tank. The conversion of organic materials to more oxidised or reduced forms occurs in treatment plants of secondary wastewater treatments and sometimes in tertiary treatment also. Disinfection and suspended particles removal are the most common techniques used to modify conventional wastewater treatment plant effluents for crop application. Advanced wastewater treatment, also known as tertiary treatment, is used in treatment technologies when a higher quality of water is desired but secondary treatment procedures cannot provide. Advanced or tertiary water treatment includes the removal of nitrogen, phosphorus, several organics and metals. Finally, the treated waters can be used for multiple purposes. Rainfall waters being less polluted, can be easily treated and fewer treatment methods will require here. However, to make them more efficient, several improvements are needed for commonly used systems like trickling filters, oxidising ponds, rotating bio contractors (RBCs), septic tanks, etc.

Review of Method and a New Tool for Decline and Inactive SARS-CoV-2 in Wastewater Treatment

Following the recent outbreak of the COVID-19 pandemic caused by the SARS-CoV-2 virus, monitoring sewage has become crucial, according to reports that the virus was detected in sewage. Currently, various methods are discussed for understanding the SARS-CoV-2 using wastewater surveillance. This paper first introduces the fundamental knowledge of primary, secondary, and tertiary water treatment on SARS-CoV-2. Next, a thorough overview is presented to summarize the recent developments and breakthroughs in removing SARS-CoV-2 using solar water disinfection (SODIS) and UV (UVA (315–400 nm), UVB (280-315 nm), and UVC (100–280 nm)) process. In addition, Due to the fact that the distilled water can be exposed to sunlight if there is no heating source, it can be disinfected using solar water disinfection (SODIS). SODIS, on the other hand, is a well-known method of reducing pathogens in contaminated water; moreover, UVC can inactivate SARS-CoV-2 when the wavelength is between 100 to 280 nanometers. High temperatures (more than 56°C) and UVC are essential for eliminating SARS-CoV-2; however, the SODIS systems use UVA and work at lower temperatures (less than45°C). Therefore, using SODIS methods for wastewater treatment (or providing drinking water) is not appropriate during a situation like the ongoing pandemic. Finally, a wastewater-based epidemiology (WBE) tracking tool for SARS-CoV-2 can be used to detect its presence in wastewater.

Mechanical Stability Is Key for Large-Scale Implementation of Photocatalytic Surface-Attached Film Technologies in Water Treatment

Replacement of classical tertiary water treatment by chemical-free sunlight-driven photocatalytic units has been often proposed. Photocatalysts are required to be cost-effective, inert, chemically stable, reusable, and easy to separate and also that they are mechanically stable. The effect of mechanical stress on a photoactive TiO2 layer, and on its effectivity for degradation of phenol as a model pollutant, has been studied during photocatalytic water treatment using NUV–vis light. Sol–gel (SG) and liquid phase deposition (LPD) methods have been used to coat spherical glass beads with the photocatalyst (TiO2). Physicochemical characterization of coated glass beads has been performed by N2 adsorption–desorption isotherms, SEM, EDXS, and AFM. Phenol photocatalyzed degradation was carried out both in stirred batch and flow reactors irradiated with a medium-pressure Hg-vapor lamp (λ &amp;gt; 350 nm). Phenol concentration was determined by HPLC, and its photoproducts were identified using HPLC/MS. In the stirred batch reactor, all LPD-coated glass beads displayed higher catalytic activity than SG-coated ones, which increased with calcination temperature, 700°C being the most efficient temperature. Preliminary etching of the glass beads surface yielded dissimilar results; whereas, phenol photodegradation with SG-coated etched glass beads is twice faster than with unetched SG ones, the rate reduces to one-third using LPD etched instead of unetched LPD glass beads. Phenol photodegradation using LPD is similar both in stirred batch and flow reactors, despite the latter uses a lower catalyst load. LPD-etched catalyst was recovered and reused in the stirred batch reactor; its activity reduced sharply after the first use, and it also lost activity in successive runs, ca. 10% of activity after each “use and recover” cycle. In the flow reactor, activity loss after the first experiment and recycling (ca. 30%) was much larger than in the following runs, where the activity remained rather constant through several cycles. LPD is more adequate than SG for TiO2 immobilization onto glass beads, and their calcination at 700°C leads to relatively strong and reactive photocatalytic films. Still, TiO2-coated glass beads exhibited very low photoactivity compared to TiO2-P25 nanoparticles, though their separation is much easier and almost costless. The durability of the catalytic layer increases when using a flow reactor, with the pollutant solution flowing in a laminar regime through the photocatalyst bed. In this way, the abrasion of the photocatalytic surface is largely reduced and its photoactivity is better maintained.

Monitoring of methylene blue monomers and dimers to control the bacterialogical water quality including application to photocatalysis.

In this study, we propose the development of a rapid and reliable method to control and to monitor microbial water quality. The methylene blue (MB) decolorization assay was based on the analysis of spectral profiles of dye in interaction with a different bacterial concentration. The determination of dye decolorization rate (DDR) shows a correlation between the MB reduction rate and the bacterial density. Moreover, the kinetic of the monomer and dimer equilibrium of MB in water mainly, the monitoring of bounded MB species in relationship with a knowed concentration of target bacteria, was allowed to establish a relationship between MB decolorization rate and bacterial density. Furthermore, this method was applied to evaluate the water quality after photocatalysis. Based on this method, the photocatalytic effects on bacterial density was highlighted by the decrease in DDR after photocatalytic treatment with fractioned times (0 to 5 h); this increase was followed by a decrease of bounded MB species and, an increase in free MB forms miming the reduction of bacterial density due to the biocide effects of photocatalysis process. However, the analysis of spectra profiles shows a weak but a continuous decrease in bounded MB dimer and monomer forms in the treated water samples exempt of culturable bacteria. Moreover, the MB spectra profiles were tended toward a negative control spectrum without superposition. Thus, the possibility of the presence of viable but non-culturable bacteria was expected; therefore, to optimize this tertiary water treatment process, an extending on proceeding time was recommended to avoid the bacterial resuscitation after photocatalysis.

Sonophotocatalytic disinfection of Shigella species under visible light irradiation: Insights into its molecular mechanism, antibacterial resistance and biofilm formation

Microbial contamination of water is one of the major sources of many diseases worldwide. Evolution of antibacterial resistance (ABR) alongside the caveats in most of the water treatment methods causes the severity of the current problem extremely vexing. This calls for an urgent need to develop new treatment methods aiming to reduce the microbial as well as ABR load in the environment. Herein, we successfully developed a visible light assisted sonophotocatalysis (SPC) using Fe/ZnO nanoparticles (NPs) for the disinfection of Shigella dysenteriae. A consortia containing S. dysenteriae and S. flexineri was also completely disinfected using SPC. Growth conditions of S. dysenteriae like growth phases and growth temperaturehad different outcomes on the overall efficacy of SPC. Compared with catalysts such as ZnO and TiO2, Fe/ZnO resulted in better disinfection. Multi-ROS production, mostly containing h+ and O2· radicals, due to the electron displacement in the catalyst and acoustic cavitation was identified as the factors behind bacterial lethality. The ROS produced was found to interfere with the metabolic activities of S. dysenteriae by causing membrane perturbation. We identified DNA damage inside the cells and the subsequent release of intracellular components. The compositional changes in the fatty acid makeup of the cells were altered as a result of SPC and few fatty acid markers indicating the stress posed by SPC were also identified. Loss of ABR in S. dysenteriae was also recorded post SPC treatment. Abatement in the biofilm forming ability of the injured bacterial cells was also recorded, proving the extremity of stress induced by SPC. Hence, the excellent efficacy of SPC in disinfecting bacteria is proposed for tertiary water treatment applications.

Oxidation of Trace Organic Contaminants (TrOCs) in Wastewater Effluent with Different Ozone-Based AOPs: Comparison of Ozone Exposure and •OH Formation

Ozone-based advanced oxidation processes (AOPs), recognized as effective methods for tertiary water treatment in view of trace organic contaminant (TrOC) removal, were investigated in this study. B...

Highly efficient removal of pharmaceuticals from water by well-defined carbide-derived carbons

In this work, we evaluate the feasibility of carbide-derived carbons (CDCs) as reliable and highly efficient adsorbents for the removal of pharmaceuticals from water. CDCs were produced from titanium carbide at temperatures within the range of 800–1400 °C employing chlorine as extraction agent. The materials were physicochemically characterized and tested in the adsorption of two relevant pharmaceuticals (diclofenac (DCF) and metronidazole (MNZ)) in aqueous solutions. We found that the specific surface area in combination with a low functionalized surface plays a key role on the adsorption capacity of the material while the average pore size determines the kinetics of the process. Notably, the CDCs showed an outstanding adsorptive behaviour compared to different conventional carbon materials under the same operating conditions, which was attributed not only to their high surface areas but mainly to their strong hydrophobic properties. The optimum material (specific surface area of 1676 m2 g−1) showed extremely high adsorption capacity values (551 and 410 mg g−1 for DCF and MNZ, respectively). Remarkably, the process was very fast (10 min of equilibrium time) even using low doses of adsorbent (0.3 mg mL−1). The performance of the optimum CDC was also demonstrated in bi-component systems while its versatility was demonstrated in a real wastewater treatment plant (WWTP) effluent, obtaining a good performance in terms of adsorption capacity (up to ∼400 mgDCF g−1) and kinetics (equilibrium time of 10 min). These results demonstrate the promise of CDCs for reliable, effective and fast flow-through tertiary water treatment.

Onsite Food Waste Processing as an Opportunity to Conserve Water in a Medical Facility Case Study, Abu Dhabi

This paper presents the case for soil and water conservation combined with waste recycling strategies in a desert type climate healthcare environment, which is based on the need for Abu Dhabi to decrease desalinated potable water consumption and increase its waste recycling rate to reduce environmental impact. The work documented in this paper forms part of the first author's Professional Doctorate change project in the United Arab Emirates (UAE), at a medical facility in use since 2015. The project is investigating two aspects: the feasibility of reusing both the site produced organic biological waste as an organic fertilizer and the effluent produced for landscape irrigation. For this paper the sole aspect of the effluent will be discussed. The context is a newly built medical facility in Abu Dhabi with a 21,600m2 building footprint area surrounded by a 29,000m2 vegetated open spaces. The city, located on the south west coast of the UAE, is dominated by sandy and salty soil, high temperature and humidity [1]. Five types of effluent generated by three types of dehydrators have been tested for general characteristics, inorganic and organic compounds, and metal parameters and analysed against local authorities’ parameters limits to verify compliance and establish suitability for landscape irrigation and water feature reuse. The effluent test results show absence of microbiological contaminants. The quality of the effluent shows that secondary and tertiary water treatment would be needed to regulate the BOD, turbidity and pH levels to align with the local regulation water recycling requirements. The next steps are for the facility dehydrator effluent to be tested onsite to provide an account of its quality for reuse and for selecting a tertiary treatment type if necessary suitable for landscape irrigation. This to understand how food waste processed onsite can impact the environment, operation and maintenance cost and practices, greenhouse gas emissions, and building systems energy consumption. This study may be relevant to local competent authorities responsible for making and adjusting standards on non-clinical wastewater reuse and recycling should dehydrators be reused at a larger city scale.

Assessment of pressure decay test for RO protozoa removal validation in remote operations

Essential requirements for remote potable water reuse in small communities include highly automated processes, remote monitoring and control, and high pathogen removal values that can be easily validated. A plant for advanced tertiary water treatment for remote operations using six pathogen barriers has been tested. It can achieve a credible Log Removal Value (LRV) for virus and bacteria well above target values recommended by current guidelines, but not for protozoa since this pathogen type is commonly resistant to most chemical disinfectants. As a result, the required LRV credit requirement for protozoa for the reverse osmosis (RO) barrier of the plant was at least 2 to reach the desired outcome. Furthermore, the maximum certified LRV for protozoa in Australia for RO in recycled water is no greater than 2 due to the lack of recognized integrity testing techniques to validate the process during operation. In this study, a pressure decay test (PDT) for RO systems is presented and verified by particle challenge testing. It is demonstrated with both laboratory scale and single element pilot scale tests that the PDT is more conservative than the particle challenge test. It is also demonstrated that frequent PDTs will not cause physical damage to membranes, based on a sample of 304 PDTs, as well as a visual check of the RO element structure and salt rejection.

Characterization of a macrophyte microcosm as a surface water treatment system for antibiotics

Natural water treatment systems provide for a means to manage nutrient (and carbon) cycles while improving water quality. We present chemical engineering design characteristics from an example flow through and model tertiary water treatment microcosm. This research demonstrates that aquatic macrophytes (Pistia stratiotes and Eichhornia crasippes) can degrade concentrations (0–10 mg/L) of oxytetracycline (OTC). First order OTC degradation rate coefficients (0.07–4.5/day) can be adjusted by altering; agitation, pH, temperature, and aeration mass flows in exudate treatment strategies when simulated wastewater was fed at 10 L/day. Further, we suggest that electronic paramagnetic resonance can be used to aid in hypothesis testing that external elicitation with phytohormones can be used to promote biological based oxidative bursts with methyl jasmonate during water treatment. Finally, we suggest there is a lack of research that considers macrophytes in more holistic natural and human use cycles. © 2015 American Institute of Chemical Engineers Environ Prog, 34: 1605–1612, 2015

Synthesis and Characterization of TiO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; Porous Films for Heterogeneous Photocatalysis

Heterogeneous photocatalysis is one of the advanced oxidation processes (AOP’s). These are very used nowadays for their implementation in tertiary water treatment with solar activation, with very good results. In this study, TiO2 porous films were synthesized by sol-gel method. Polyethylene glycol (PEG) 4000 was used as a templating reagent, which is oxidized at a lower temperature than TiO2. This allows the formation of a “skeleton” of porous TiO2 with increased surface area, resulting in higher photocatalytic activity. The film characterization was made with help of FE-SEM microscope, XRD diffractometer and scotch tape test. Finally, the oxidation experiments were performed using methylene blue as a model pollutant and they revealed an increase in the photocatalytic activity of porous films in comparison with the non-porous films.

“Dye Industry Effluent Treatment Using Cactus (Opuntia) And Water Hyacinth (Eichhornia Crassipes)”

Coagulation is an important wastewater treatment process used to reduce water turbidity and normally precedes the more complex secondary and tertiary water treatment process. In this study, the effectiveness of a natural coagulant derived from a cactus species for turbidity removal from dye industry effluent. Other parameters such as pH as well as colour were also studied. The amount of cactus added was well correlated with final turbidity of the water. High turbidity removal determined in this study indicates that cactus (opuntia) and water hyacinth (eichhornia crassipes) has the potential to be utilised for waste water treatment applications.

Achieving a Green Solution: Limitations and Focus Points for Sustainable Algal Fuels

Research investigating the potential of producing biofuels from algae has been enjoying a recent revival due to heightened oil prices, uncertain fossil fuel sources and legislative targets aimed at reducing our contribution to climate change. If the concept is to become a reality however, many obstacles need to be overcome. Recent studies have suggested that open ponds provide the most sustainable means of cultivation infrastructure due to their low energy inputs compared to more energy intensive photobioreactors. Most studies have focused on strains of algae which are capable of yielding high oil concentrations combined with high productivity. Yet it is very difficult to cultivate such strains in open ponds as a result of microbial competition and limited radiation-use efficiency. To improve viability, the use of wastewater has been considered by many researchers as a potential source of nutrients with the added benefit of tertiary water treatment however productivity rates are affected and optimal conditions can be difficult to maintain year round. This paper investigates the process streams which are likely to provide the most viable methods of energy recovery from cultivating and processing algal biomass. The key findings are the importance of a flexible approach which depends upon location of the cultivation ponds and the industry targeted. Additionally this study recommends moving towards technologies producing higher energy recoveries such as pyrolysis or anaerobic digestion as opposed to other studies which focused upon biodiesel production.

Electro-oxidation of reverse osmosis concentrates generated in tertiary water treatment

This work investigates the application of the electro-oxidation technology provided with boron doped diamond (BDD), an electrode material which has shown outstanding properties in oxidation of organic and inorganic compounds, for the treatment of reverse osmosis (RO) concentrates generated in tertiary wastewater treatment plants (WWTP). Chemical oxygen demand (COD), ammonium and several anions were measured during the electro-oxidation process, and the influence of the applied current density (20–200 A/m 2) was analysed on process kinetics. Analytical assessment showed that several emerging pollutants (pharmaceuticals, personal care products, stimulants, etc.) were presented both in the effluent of the secondary WWTP as well as in the RO concentrate. For this reason, a group of 10 emerging pollutants, those found with higher concentrations, was selected in order to test whether electro-oxidation can be also applied for their mitigation. In the removal of emerging pollutants the electrical current density in the range 20–100 A/m 2 did not show influence likely due to the mass transfer resistance developed in the process when the oxidized solutes are present in such low concentrations. Their removal rates were fitted to first order expressions, and the apparent kinetic constants for the anodic oxidation of each compound were calculated. Finally, the formation of trihalomethanes (THMs) has been checked; concluding that after selecting the appropriate operational conditions the attained concentration is lower than the standards for drinking water established in European and EPA regulations.