Application of novel Modified Biological Aerated Filter (MBAF) as a promising post-treatment for water reuse: Modification in configuration and backwashing process

Biological Aerated Filter (BAF) reactors due to their plentiful biomass, high shockability, high efficiency, good filtration, availability and lack of need for large land areas, are enjoying from great importance in advanced wastewater treatment. Therefore, in this study, Polystyrene Coated by Sand (PCS) was produced as a novel media and its application in a modified down-flow BAF structure for advanced wastewater treatment was assessed in two steps. In step one, the backwash effluent did not return to the system, while in step two backwash effluent returned to increase the water reuse efficiency. The backwash process was also studied through three methods of Top Backwashing (TB), Bottom Backwashing (BB), as well as Top and Bottom Backwashing Simultaneously (TBBS). The results showed that return of backwash effluent had no significant effect on the BAF effluent quality. In the second step similar to the first one with slight differences, the residual average concentrations of TSS, BOD5, and COD at the effluent were about 2.5, 8.2, and 25.5 mg/L, respectively. Additionally, in step two, the mean volume of disposal sludge/volume of treated water (v(ds)/v(tw)) decreased a large extent to about 0.088. In other words, the water reuse has increased to more than 99.91. The backwash time in methods of TB and BB were 65 and 35 min, respectively; however, it decreased in TBBS methods to 25 min. The concentrations of most effluent parameters in this system are in concordance with the 2012 EPA Agriculture Standards, even for irrigation of Non-processed agricultural crops and livestock water consumption. (C) 2017 Elsevier Ltd. All rights reserved

Synthesis of polystyrene coated by sand (PCS) as a novel media in modified biological aerated filters (BAF) for advanced municipal wastewater treatment: a comparative assessment

In this study a novel media, polystyrene coated by sand (PCS) was made and then applied in a -pilot-scale down-flow biological aerated filter (BAF), named PCS BAF. The efficiency of PCS BAF reactor was compared with efficiencies of puzzolana BAF, gravel BAF, and polystyrene BAF in advanced domestic wastewater treatment through three stages. The inner structure of BAFs consisted of a media with a height of 150 cm for biological attached growth that was modified by a 20 cm layer of silica particles at the bottom of columns to increase the reactors' performance. The physical and chemical parameters of turbidity, BOD5, TCOD, and SCOD, as well as parameters related to backwashing were investigated for BAFs' efficiency. Results of this research indicated that PCS BAF can decrease the turbidity, BOD5, TCOD, and SCOD in the influent, from 20 NTU, 22, 53, and 36 mg/L, to a rate of 1.3 NTU, 9, 26, and 21 mg/L in the effluent, respectively. Moreover, the backwashing time required for PCS BAF was less than half of the other three BAF reactors and the backwashing interval was about once every 19 d

Assessment of hospitalization and mortality from exposure to PM10 using AirQ modeling in Ilam, Iran

The aims of this study were to assess the health impact of PM10 on inhabitants and to investigate the trend of PM10 concentrations in Ilam, Iran, from 2012 to 2015. For these aims, daily average concentration of PM10 was obtained from continuous monitoring stations in the study area. Mortality and morbidity due to PM10 were assessed by AirQ software developed by World Health Organization (WHO). Based on the results, the annual mean concentrations of PM10 in all of years were more than WHO guideline and PM10 concentration had a decreasing trend in this study period. Total mortality attributed to PM10 was found to be 49 cases in 2012, 25 in 2013, and 33 in 2014. Hospital admission due to respiratory diseases was the most impact due to PM10. Increase in relative risk (RR) with every 10 mu g/m(3) increase in PM10 from 2012 to 2015 years for total mortality, respiratory disease hospitalization, and hospital admissions were 0.6, 0.8, and 0.9, respectively. The results of this study indicated that air pollution is one of the major problems in this urban area and AirQ model as simple tool can help to design preventive and controlling programs in order to reduce human health effects of pollutants

Investigation of modified microbial desalination cell performance in sweetening of saltwater

BACKGROUND AND OBJECTIVE: Lack of enough fresh water is a global challenge. Water sweetening can be done using thermal or membrane systems that each of them requires significant energy. Microbial desalination cell (MDC) is a new technology which can desalinate water, generate electricity, and simultaneously purify wastewaters in a reactor. However, low current generation and deionization are from main challenges of this process. This study aimed to improve the MDCs efficacy. METHODS: In this experimental study, a modified three-cell MDC consisted of anode, cathode, and middle chambers, was designed in order to water desalination (20 g/L NaCl). Here, the cathode solution was diffused via ozone (O3-MDC) and the middle saline solution was pretreated into an ultrasonic bath. Subsequently, the results achieved in O3-MDC in terms of water desalination and current generation were compared against those of another reactor operated under oxygen diffusion (O2-MDC), and without ultrasonic pretreatment (control). Biofilm formation on anode surface and dominant bacteria in the O3-MDC reactor were studied using Scanning Electron Microscopy (SEM), and 16S rRNA gene sequencing, respectively. FINDINGS: Saltwater pre-treatment caused to increase the electrical conductivity from 28.1 ms/cm to 35.5 ms/cm; and then current generation from 191 to 131 mV after 24 hr operation. O2-MDC and O3-MDC were able to remove 74 and 55.58 of NaCl from water, respectively. Proteobacteria, firmicuites and acidobacteria were dominant microbial communities in the anode biofilm based on 16S rRNA sequencing. CONCLUSION: Based on the results of this study, modified MDC with ozone and ultrasound waves could be an appropriate option for desalinating salt water. © 2018, Babol University of Medical Sciences. All rights reserved

Optimizing the removal of humic acid with polyaluminum chloride and polyaluminum ferric chloride as green coagulants using response surface methodology

Humic acid is a major precursor of chlorinated byproducts that need to be removed from water, via treatment, given their adverse effects on human health. The current study aimed at identifying the optimal conditions to remove humic acid from surface water, using coagulants such as polyaluminum chloride (PACl) and polyaluminum ferric chloride (PAFCl). The effects of independent variables such as total organic carbon (TOC) concentration (1.6-7 mg/L), pH level (5-9), and coagulant dosage (10-50 mg/L) on humic acid removal were studied using response surface methodology and central composite design. A coagulant dose of 15.72 mg/L (for PACl and PAFCl), TOC concentration of 2.66 mg/L, and pH of 7.84 comprised the optimal conditions, and the removal efficiencies of 97.55 and 98.18 were obtained with PACl and PAFCl, respectively. Zeta potential analysis showed that the leading mechanism for coagulation, with both coagulants, was charge neutralization. PACl and PAFCl had adequate potential to remove humic acid from surface water, but PAFCl had a better performance regarding the treatment of aluminum residuals

Investigation of Modified Microbial Desalination Cell performance in Sweetening of Saltwater

BACKGROUND AND OBJECTIVE: Regarding fresh water scarcity rake up controversies in many parts of the world, desalinating of water and wastewaters has now been taken into consideration. Microbial desalination cell (MDC) is a new technology which can desalinate water, generate electricity, and simultaneously purify wastewaters in a reactor. However, low current generation and deionization are from main challenges of this process. This study aimed to improve the MDCs efficacy. METHODS: A modified three-cell MDC consisted of anode, cathode, and middle chambers, was designed in order to water desalination (20 g/L NaCl). Here, the cathode solution was diffused via ozone (O3-MDC) and the middle saline solution was pretreated into an ultrasonic bath. Subsequently, the results achieved in O3-MDC in terms of water desalination and current generation were compared against those of another reactor operated under oxygen diffusion (O2-MDC), and without ultrasonic pretreatment (control). Biofilm formation on anode surface and dominant bacteria in the O3-MDC reactor were studied using Scanning Electron Microscopy (SEM), and 16S rRNA gene sequencing, respectively. FINDINGS: Saltwater pre-treatment caused to increase the electrical conductivity from 28.1 ms/cm to 35.5 ms/cm; and then current generation from 191 to 131 mV after 24 hr operation. O2-MDC and O3-MDC were able to remove 74% and 55.58% of NaCl from water, respectively. Proteobacteria, firmicuites and acidobacteria were dominant microbial communities in the anode biofilm based on 16S rRNA sequencing. CONCLUSION: Modified MDC can be a good option for water desalination if properly navigated. Although the process is still subject to some limitations, conducting such studies can provide basics of process operationalization and commercialization

Photocatalytic degradation of microcystin-LR using BiVO4 photocatalysts under visible light irradiation: modelling by response surface methodology (RSM)

The microcystin-LR (MC-LR) is a potentially dangerous toxin for animals and human health. So, MC-LR removal from the environment by the use of photocatalysts is recommended. Generally, traditional photocatalysts are dependent on UV light and consume high energy and also produce high heat. So, the use of photocatalysts with low-energy consumption, feasible, and reliable properties that activate in the visible light is very important. The aim of the present study was the removal of microcystin-LR (MC-LR) in visible light by synthesised bismuth vanadate (BiVO4) with the hydrothermal method. The BiVO4 characteristics were determined by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FT-IR) spectra. The Response Surface Methodology (RSM) was used to survey the effects of operating variables such as pH, contact time, and catalyst dose on MC-LR removal. The results showed that the increase of contact time and catalyst dose had a positive effect on enhancing the removal efficiency of MC-LR, but the effect of pH was negative. The maximum removal efficiency of MC-LR at pH = 5, contact time = 180 minutes and catalyst dose = 0.5 g/l was equal to 93.19. Therefore, BiVO4 as an innovative photocatalyst had a suitable effect on the MC-LR degradation under visible light. © 2020 Informa UK Limited, trading as Taylor & Francis Group

The performance of TiO2/NaY-zeolite nanocomposite in photocatalytic degradation of Microcystin-LR from aqueous solutions: Optimization by response surface methodology (RSM)

Background: Microcystin (MC) is a hepatotoxic and carcinogenic toxin that is generated by cyanotoxins which can have adverse effects on the human health. Therefore, it is very important to remove it from the environment. This study was performed to investigate the efficiency of titanium dioxide (TiO2)/NaY-zeolite (T/N-Z) nanocomposite for removal of MC-LR under ultraviolet light. Methods: In the present study, T/N-Z nanocomposite was synthesized using the hydrothermal method. Specification of the photocatalysts was determined by the field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) spectra. The response surface methodology (RSM) was used to survey the effects of operating variables such as pH, contact time, and catalyst dose on the removal of MC-LR. The MC-LR concentration was measured by high-performance liquid chromatography (HPLC). Results: It was revealed that the increase of contact time and catalyst dose had a positive effect on enhancing the removal efficiency of MC-LR, but pH had a negative effect. Finally, the maximum MC-LR removal efficiency was 97.63, which occurred at pH = 5, contact time = 120 min, and catalyst dose = 1.2 g/L. Conclusion: In general, T/N-Z composite in aqueous solutions under the UV light can easily decompose MC-LR and it can also be proposed as an efficient composite for removal of MC-LR from contaminated water

An overview report on the application of heteropoly acids on supporting materials in the photocatalytic degradation of organic pollutants from aqueous solutions

Organic pollutants contaminate water resources and the environment when discharged into water streams. Also, the presence of these materials in incompletely treated or untreated wastewater leads to serious environmental hazards. The hydroxyl radicals and holes are regarded as the most oxidant species in the degradation of organic pollutants using the studied composites. The results of this review show that heteropoly acids on supporting materials could be considered as appropriate photocatalysts in the removal of organic pollutant from aqueous solutions

Evaluation of a novel integrated membrane biological aerated filter for water reclamation: A practical experience

The use of treated wastewater in addition to solving the problem of water shortage, can increase soil fertility and reduce the use of chemical fertilizers. We aim to provide a high-quality effluent to feed membrane system, reduce treatment costs and enhance the efficiency of wastewater recycling. All experiments were conducted on a novel integrated membrane biological aerated filter (IMBAF) consisting of a down flow cylindrical biological aerated filter (BAF) filled by silica and a novel sand-coated polystyrene granules (SCP), followed by ultrafiltration (UF) and reverse osmosis (RO) membranes. IMBAF reactor, with 73.6 L volume, was operated for 270 days (in three 90-day stages) with different conditions of returning backwash water. Accordingly, BAF generated high quality water for feeding UF membrane with 94.2, 68, 54.4, 91.2, and 99.95 of turbidity, 5-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), oil and grease (O & G), fecal coliform (FC) removal, respectively. At the end of stage 3, 99.88 of influent was recycled by UF and only 0.12 was disposed of as sludge. The BAF and UF module efficiently promote the quality of water entering RO system. After 75 days of continuous operation, the increase in trans-membrane pressure (TMP) and also decrease in RO membrane permeability were about 14 and 9.4, respectively, indicating low clogging of the membrane. The use of BAF structure designed in this study increases the wastewater recycling rate, decreases membrane clogging and thereby reduces the costs of concentrate disposal and chemical cleaning