removal efficiencies
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Author(s):  
Jiachao Yao ◽  
Yu Mei ◽  
Junhui Jiang ◽  
Guanghua Xia ◽  
Jun Chen

In this work, an electrochemical method for chemical oxygen demand (COD) and total nitrogen (TN, including ammonia, nitrate, and nitrite) removal from wastewater using a divided electrolysis cell was developed, and its process optimization was investigated. This process could effectively relieve the common issue of NO3−/NO2− over-reduction or NH4+ over-oxidation by combining cathodic NO3−/NO2− reduction with anodic COD/NH4+ oxidation. The activity and selectivity performances toward pollutant removal of the electrode materials were investigated by electrochemical measurements and constant potential electrolysis, suggesting that Ti electrode exhibited the best NO3−/NO2− reduction and N2 production efficiencies. In-situ Fourier transform infrared spectroscopy was used to study the in-situ electrochemical information of pollutants conversion on electrode surfaces and propose their reaction pathways. The effects of main operating parameters (i.e., initial pH value, Cl− concentration, and current density) on the removal efficiencies of COD and TN were studied. Under optimal conditions, COD and TN removal efficiencies from simulated wastewater reached 92.7% and 82.0%, respectively. Additionally, reaction kinetics were investigated to describe the COD and TN removal. Results indicated that COD removal followed pseudo-first-order model; meanwhile, TN removal followed zero-order kinetics with a presence of NH4+ and then followed pseudo-first-order kinetics when NH4+ was completely removed. For actual pharmaceutical wastewater treatment, 79.1% COD and 87.0% TN were removed after 120 min electrolysis; and no NH4+ or NO2− was detected.


2022 ◽  
Vol 31 (2) ◽  
pp. 135-142
Author(s):  
Lovely Aktar ◽  
Mohammad Moniruzzaman ◽  
Yasuzo Sakai ◽  
Mihir Lal Saha

This study was undertaken to evaluate the removal of lipid-rich organic matter from wastewater by lipase producing bacteria. Ten potential lipase producing bacteria were isolated from lipid-rich environments in and around Dhaka Metropolitan city. Three of them produced lipase higher than 10 U/ml. These three isolates and their consortium were used for synthetic wastewater treatment in the laboratory. The initial COD value of synthetic wastewater was 1,200 mg/l. COD removal efficiencies in the synthetic wastewater were 74.75, 73.33 and 66.67% by the Stenotrophomonas maltophilia e-a22, Pseudomonas aeruginosa 12 and Bacillus subtilis 20B, respectively. Stenotrophomonas maltophilia showed better COD removal performance (74.75%) in case of monoculture. But consortium showed better COD removal (83.33%) than that of monoculture. Therefore, it could be concluded that consortium of three isolates will be more useful for wastewater treatment as seed cultures in the wastewater treatment plant associated with the lipid-rich wastewater. Plant Tissue Cult. & Biotech. 31(2): 135-142, 2021 (December)


2022 ◽  
Vol 964 (1) ◽  
pp. 012030
Author(s):  
Pham-Hung Duong ◽  
Ngoc-Han T. Huynh ◽  
Yong-Soo Yoon

Abstract This study was carried out to assess the treatment ability of color, dye, and COD in the dyeing wastewater containing C.I Reactive Blue 160 by ozonation system. Both batch and continuous operating modes with concurrent and counter-current flows were investigated. The effects of the ozone gas flow rate, pH, temperature, Na2CO3 concentration, and initial dye concentration were evaluated. The decolorization, dye removal efficiencies, and mineralization ability of COD by ozonation were determined. The results indicated that ozonation had high efficiency in the treatment of dyeing wastewater containing C.I Reactive Blue 160. The treatment performance was affected by the ozone gas flow rate, pH, temperature, Na2CO3 concentration, and initial dye concentration. The removal efficiency of color, dye, and COD were 98.04%, 99.84%, and 87.31% for the treatment of 200 mg/L initial dye concentration in batch mode with 30 min ozonation time, respectively. In the continuous operation and counter-current flow, the color, dye, and COD removal efficiencies reached 97.24%, 99.76%, and 86.38% after 30 min HRT, respectively, and higher than concurrent flow. The reaction of ozone and C. I Reactive Blue 160 was the first-order reaction in both batch and continuous operation. The complete mineralization required 90 min ozonation time.


Atmosphere ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 33
Author(s):  
Han-Nui Gil ◽  
Trieu-Vuong Dinh ◽  
Jee-Hyun Lee ◽  
Byeong-Gyu Park ◽  
In-Young Choi ◽  
...  

A high humidity at a high temperature presents a common challenge in monitoring the air pollutants emitted from stationary sources. Thus, humidity removal is a pivotal issue. In this study, the effect of humidity pretreatment devices (HPDs) on hydrogen chloride (HCl) gas emitted from an incinerator stack was investigated. A conventional cooler (HPD_CL), and poly-tube (HPD_NP) and single-tube (HPD_NS) Nafion™ dryers were used as HPDs in this study. HCl concentrations varied at five and 10 parts per million in volume (ppmv). Low (i.e., ~4%) and high (i.e., ~17%) humidities were generated at 180 °C. The removal efficiencies of humidity and the loss rates of HCl by the devices were determined. The removal efficiencies of humidity by HPD_CL and the two dryers were found to be similar, at approximately 85% at a low humidity and 95% at a high humidity. In terms of HCl loss rates, HPD_CL revealed the highest loss rates in all conditions (i.e., >95%), followed by HPD_NP and HPD_NS. At normal room temperature (i.e., 25 °C), the HCl loss rates of HPD_NP were >40% at a low humidity and >70% at a high humidity, while those of HPD_NS were >10% at a low humidity and >60% at a high humidity. The performance of the two dryers improved when they were heated to 80 °C. However, this temperature caused damage to the dryers, which reduced their lifetime.


Author(s):  
Olga Długosz ◽  
Anita Staroń ◽  
Paulina Brzoza ◽  
Marcin Banach

AbstractThe paper presents the photodegradation process of one-, two- and three-component dye mixtures by ZnO-SnO2 nanoparticles. After 60 min of running the processes, the dye removal efficiencies of 76.44, 72.69, 62.43, 77.00 and 92.46% for MB, RB, TB, MO and YQ degradation, respectively, were obtained. For binary and ternary systems, dye removal efficiencies for all cases exceeded 70%. When the binary and ternary dye mixtures were tested, the photodegradation efficiencies of ZnO-SnO2 were similar to those of the single mixtures, indicating that this material could be used in industrial applications in the future. The focus of the study was to investigate the effect of sorption on photodegradation efficiency and the presence of both cationic and anionic dyes on their degradation efficiency under UV light. The significance of the effect of sorption on the degradation efficiency allowing the interaction of the catalyst with the dyes removed was confirmed. The main factor influencing sorption and consequently photocatalysis was the nature of the dye. It was confirmed that the positively charged ZnO-SnO2 surface effectively sorbs the dyes and causes their degradation.


2021 ◽  
Vol 13 (24) ◽  
pp. 13665
Author(s):  
Jasmine Sie Ming Tiong ◽  
Yi Jing Chan ◽  
Jun Wei Lim ◽  
Mardawani Mohamad ◽  
Chii-Dong Ho ◽  
...  

Food waste (FW) utilized as substrate for anaerobic digestion (AD) to produce biogas is promising. Simultaneously, waste is handled and value-added products such as biogas and fertilizer are produced. Palm oil mill effluent (POME) is used as the co-substrate. This study aims to simulate the complete process flow of anaerobic co-digestion (AcoD), consisting of pre-treatment of feedstock, biogas upgrading, wastewater treatment and sludge dying using SuperPro Designer. Parameters, namely hydraulic retention time (HRT), recycle ratio of sludge, water to FW ratio (kg/kg) and co-substrate to FW ratio (kg/kg), would affect the performance of digester. The optimization of these parameters is performed using Design-Expert software, involving response surface methodology (RSM). The effects on responses such as methane flow, chemical oxygen demand (COD) and volatile solid (VS) removal efficiencies are analyzed. In treating 25,000 kg/h of feed, the optimized values for HRT, recycle ratio, water to feedstock ratio, POME to FW ratio are 37.2 days, 0.381, 0.027 and 0.004, respectively. The methane yield is 0.30 L CH4/g of COD removed, with COD and VS removal efficiencies of 81.5% and 68.9%, respectively. The project is profitable, with a payback period of 6.14 years and net present value (NPV) of $5,680,000. A comprehensive understanding of AD matures it for commercialization purposes.


Processes ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 2200
Author(s):  
Georgios D. Gikas ◽  
Vassiliki A. Papaevangelou ◽  
Vassilios A. Tsihrintzis ◽  
Maria Antonopoulou ◽  
Ioannis K. Konstantinou

We assessed constructed wetland (CW) performance in the removal of six emerging pollutants (EPs) from university campus wastewater. The EPs considered were: diethyl phthalate (DEP), di-isobutyl phthalate (DIBP), di-n-octyl phthalate (DNOP), bis(2-ehtylxexyl) phthalate (DEHP), tris(1-chloro-2-propyl) phosphate (TCPP) and caffeine (CAF). Six pilot-scale CWs, i.e., three horizontal subsurface flow (HSF) and three vertical flow (VF), with different design configurations were used: two types of plants and one unplanted for both the HSF and the VF, two hydraulic retention times (HRT) for the HSF, and two wastewater feeding strategies for the VF units. The results showed that the median removals in the three HSF-CWs ranged between 84.3 and 99.9%, 79.0 and 95.7%, 91.4 and 99.7%, 72.2 and 81.0%, 99.1 and 99.6%, and 99.3 and 99.6% for DEP, DIBP, DNOP, DEHP, TCPP, and CAF, respectively. In the three VF-CWs, the median removal efficiencies range was 98.6–99.4%, 63.6–98.0%, 96.6–97.8%, 73.6–94.5%, 99.3–99.5% and 94.4–96.3% for DEP, DIBP, DNOP, DEHP, TCPP and CAF, respectively. The study indicates that biodegradation and adsorption onto substrate were the most prevalent removal routes of the target EPs in CWs.


2021 ◽  
Author(s):  
Emre Burcu Özkaraova ◽  
Elif Güven Oral

In order to increase the reuse of wastes and residues, as required by the Waste Framework Directive, the potential use of waste, residue and natural minerals as low-cost permeable reactive barrier (PRB) materials was investigated. The performance of a kitchen waste compost, sepiolite and steel slag was compared with that of volcanic slag, pumice and activated carbon in removing specific contaminants from landfill leachate. The experiments represented that the activated carbon removed 27% of the ammonium (NH4+), 75% of the chemical oxygen demand (COD) and 100% of the phosphate (PO43–), zinc (Zn2+) and nickel (Ni2+) from the landfill leachate. Volcanic slag exhibited removal efficiencies of 50% COD and 100% PO43– and pumice exhibited removal efficiencies of 20% NH4+, 27% Zn2+, 65% COD and 100% PO43–. The reactive materials were also checked for their potential in releasing unwanted constituents and represented different levels of the solute (e.g., PO43–, SO42–, NH4+) release. Among the reactives, sepiolite was found to be the reactive material reflecting a minor release (e.g., Zn2+, Cd2+ and Ni2+), but also delivering removal efficiencies of 40, 50, 65, 95, 97, 98, 98 and 100% for Ni2+, COD, Zn2+, SO42–, Cl–, F–, NH4+ and PO43–, respectively. The results show that the studied materials have the potential as reactives for PRB systems treating high strength contaminant plumes.


Author(s):  
Chen Xu ◽  
Liupeng Wang ◽  
Zaohong Liu ◽  
Guanjun Cai ◽  
Jian Zhan

Abstract In this study, an immobilized algae and bacteria symbiotic biofilm reactor (ABSBR) with pink luminescent filler (PLF) was constructed. The effects of PLF addition in the construction of an algae and bacteria symbiotic biofilm system on the nitrogen and phosphorus removal efficiencies and algae viability were evaluated. Our results showed that for influent TN and TP concentrations of 40 ± 5 and 5 ± 0.8 mg/L, respectively, the pollutant removal rates (PRRs) of TN and TP by the ABSBR can reach up to 74.74 and 88.36%, respectively. The chlorophyll-a (chl-a) concentration on the PLF reaches approximately 5,500 μg/L with a specific oxygen generation rate (SOGR) of 65.48 μmolO2 mg−1Chl-a h−1. These results indicate that the adding PLF into algae and bacteria symbiosis systems can effectively improve the nitrogen and phosphorus removal efficiencies of the sewage as well as increase biomass and viability of the algae in the system.


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