Design and application of new type of oxygen supplier for water and wastewater treatment

A new oxygen supplier was designed to inject both ozone and air into the water under high pressure. The oxygen transfer coefficient (KLa) of the system with air and ozone were 0.0264 and 0.4900, respectively. The oxygen transfer efficiencies of the system with ozone and air were 73.58 and 52.17%, respectively. The system could be applied to increase the dissolved oxygen (DO) in domestic wastewater. DO of the wastewater from septic tank was increased from 0.0 to 4.9 ± 0.5 mg/L within 1.6 h by the system with air injection and up to 8.0 ± 0.5 mg/L within 1.6 h with ozone injection. The system with ozone injection could reduce the COD and BOD5 by 54.6 ± 3.5 and 50.9 ± 3.4%, respectively, by increasing the DO. The system could be also be applied into shrimp ponds to increase DO. The DO of the water was increased from 2.5 to 4.3 ± 0.5 and 6.1 ± 0.7 mg/L within 20 and 80 min, respectively, by the system with ozone injection. Also, the system could reduce the organic matter during operation. The COD and BOD5 were reduced by 81.2 ± 1.2% and 57.1 ± 3.0%, respectively, within 1.6 h by the system with ozone injection

Effects of Cr3+ and Ni2+ on the efficiency and performance of sequencing batch reactor (SBR) system

Sequencing batch reactor (SBR) system at hydraulic retention time (HRT) of 1.5 days could be used for the treatment of Ladkrabang industrial estate wastewater (LIWW) with high Cr3+ and Ni2+ removal efficiencies of 80.7 ± 17.9 and 53.5 ± 25.1%, respectively. Bio-sludge of SBR system with synthetic industrial estate wastewater (SIWW) showed the highest Cr3+ and Ni2+ adsorption yields of 36.00 ± 9.80 and 31.59 ± 9.67 mg/g, respectively but they were reduced to 25.20 ± 8.38 and 20.49 ± 7.20 mg/g, respectively with LIWW. Cr3+ and Ni2+ strongly suppressed the growth and activity of heterotrophic bacteria. Ni2+ at 3.0 mg/L did not impact either nitrifying or denitrifying bacteria, while the growth and activity of denitrifying bacteria was suppressed at 3.0 mg/L Cr3+. The other advantage of SBR system was that the bio-sludge could adsorb inorganic matters from LIWWs, which contains high inorganic content about 33%.Key words: Adsorption, chromium, heavy metals, nickel, sequencing batch reactor (SBR) system

Observation of Nitrogen and Phosphorus Removals and Accumulations in Surface Flow Constructed Wetland (SFCW)

The tropical emergent plant species; Cyperus involucratus, Canna siamensis, Heliconia sp., Hymenocallis littoralis, Typha augustifolia and Thalia dealbata were used to observe nutrients (total phosphorus: TP and total nitrogen: TN) removal efficiencies of surface flow constructed wetland (SFCW). The system was operated at different hydraulic retention time (HRT) of 1, 3 and 5 days and the average atmospheric temperature of 29.1 ± 4.9oC. The seafood industrial wastewater was employed as the influent. The high biomass production plant species; Cyperus involucratus, Typha augustifolia and Thalia dealbata could generate the high oxidative environment. Amount of N and P accumulations in plant tissue were increased with the increase of plant biomass production. The system did not show any significantly different on N and P accumulations among the tested-emergent plant species. But the amount of accumulated-N and P were increased with the increase of HRT. N accumulations in plant tissue, effluent, sediment and media of the system with the tested-emergent plant species under HRT of 1-5 days were in the range of 2.17-43.80%, 7.91-27.75%, 19.62-36.86% and 14.39-31.88%, respectively. Also, P accumulations were 0.79-17.01%, 20.35-28.37%, 40.96-56.27% and 9.09-20.47%, respectively

Some properties on the application of Candida utilis TISTR No. 5001 into sequencing batch reactor (SBR) System

The use of C. utilis TISTR No. 5001 as a substitute for bacterial sludge in the SBR system was examined in this study. To stimulate and maintain Candida utilis TISTR No. 5001 as the dominant strain in the SBR system, the initial pH of wastewater had to be controlled in the acidic range (5-6). The laboratory scale SBR system (10-L reactor volume) with C. utilis TISTR No. 5001 (Y-SBR system) operating at 1cycle/day, ambient temperature (25-29oC), impeller speed of 60 rpm, dissolved oxygen of 2.0-2.5 mg/l and replacement volume of 2.50 L/d, showed the highest COD, BOD5 and total nitrogen (TN) removalefficiencies of 97.2±1.6, 97.6±1.6 and 53.1±0.6%, respectively, with synthetic waste water, SWW (pH5), under an organic loading of 0.45 kg BOD5/m3-d. The effluent NO3 - and effluent NO2 - of the system wereonly 0.42±0.06 mg/l and 0.05±0.007 mg/l, respectively. The sludge age (SRT) and sludge volume index (SVI) of the system were 19±2.3 days and 72±8.2 ml/g, respectively. The SBR system with a mixedculture of C. utilis TISTR No. 5001 and bacterial sludge (Y-SBS-SBR system) showed high organic removal efficiencies of higher than 95% with both acidic-SWW and alkaline-SWW. Furthermore, it showed the highest total nitrogen (TN) removal efficiency with SWW (pH 5). The TN removal efficiency with SWW (pH 8) under the lowest organic loading of 0.13 kg BOD5/m3-d was only 22.1±10.2%, while it increased to 35.4±1.0% for SWW (pH 5)

Evaluation of a pilot scale high pressure plasma ozonizer for use in wastewater treatment

The plasma technique which is used for wastewater treatment is one of the most effective processes for ozone production. In this study, a laboratory scale plasma technique ozonizer designed for treating wastewater was tested under various operation conditions which included voltage (E), current frequency (f), electrical current (I), gas pressure in the system (P), distance of electric dipoles (d), type of electric pole and energy consumption. The optimum configuration for the highest ozone production efficiency was observed using a needle shape electrode when voltage (E) was set at 18,000 volts, f at 1,000 Hz, I at 35 mA, P at 1.3x105 N/rn2 and d at 0.003 m. Using the configuration, the ozonizer efficiency was tested in treatment of domestic and shrimp farm wastewater. Results showed that the ozonizer can significantly improve the quality of wastewater within 60 min of treatment.Key words: Ozone, ozonizer, oxidizer, plasma, high pressure, plasma system

Decolorization of synthetic melanoidins-containing wastewater by a bacterial consortium

The presence of melanoidins in molasses wastewater leads to water pollution both due to its dark brown color and its COD contents. In this study, a bacterial consortium isolated from waterfall sediment was tested for its decolorization. The identification of culturable bacteria by 16S rDNA based approach showed that the consortium composed of Klebsiella oxytoca, Serratia mercescens, Citrobacter sp. and unknown bacterium. In the context of academic study, prevention on the difficulties of providing effluent as well as its variations in compositions, several synthetic media prepared with respect to color and COD contents based on analysis of molasses wastewater, i.e., Viandox sauce (13.5% v/v), caramel (30% w/v), beet molasses wastewater (41.5% v/v) and sugarcane molasses wastewater (20% v/v) were used for decolorization using consortium with color removal 9.5, 1.13, 8.02 and 17.5%, respectively, within 2 days. However, Viandox sauce was retained for further study. The effect of initial pH and Viandox concentration on decolorization and growth of bacterial consortium were further determined. The highest decolorization of 18.3% was achieved at pH 4 after 2 day of incubation. Experiments on fresh or used medium and used or fresh bacterial cells, led to conclusion that the limitation of decolorization was due to nutritional deficiency. The effect of aeration on decolorization was also carried out in 2 L laboratory-scale suspended cell bioreactor. The maximum decolorization was 19.3% with aeration at KLa = 2.5836 h-1 (0.1 vvm)

Performance Improvement of a Sequencing Batch Reactor for Treating Tannery Wastewaters

[EN] Tannery wastewater has a high environmental impact due to its low biodegradability. Sequencing batch reactors (SBRs) are an established method for treating highly polluted wastewater. To minimize the hydraulic retention time (HRT) of the SBRs, various HRT values were tested and the best value was chosen according to the removal efficiency of the soluble chemical oxygen demand (COD). A series of experiments was then carried out with two cationic polyelectrolytes added to the system in two different modes to improve the effluent quality. Both modes were evaluated in terms of the soluble COD, suspended solid concentration, and turbidity of the final effluent. The results showed that reducing the HRT to two days did not diminish the COD removal efficiencies.This work was supported by the Universitat Politecnica de Valencia (Project Ref.: PAID-06-10-2269).Balaguer-Arnandis, E.; Cuartas Uribe, BE.; Bes-Piá, M.; Mendoza Roca, JA.; Galiana Aleixandre, MV. (2017). Performance Improvement of a Sequencing Batch Reactor for Treating Tannery Wastewaters. Chemical Engineering & Technology. 40(9):1666-1673. https://doi.org/10.1002/ceat.201600410S1666167340

Rotating biological contactors : a review on main factors affecting performance

Rotating biological contactors (RBCs) constitute a very unique and superior alternative for biodegradable matter and nitrogen removal on account of their feasibility, simplicity of design and operation, short start-up, low land area requirement, low energy consumption, low operating and maintenance cost and treatment efficiency. The present review of RBCs focus on parameters that affect performance like rotational speed, organic and hydraulic loading rates, retention time, biofilm support media, staging, temperature, influent wastewater characteristics, biofilm characteristics, dissolved oxygen levels, effluent and solids recirculation, stepfeeding and medium submergence. Some RBCs scale-up and design considerations, operational problems and comparison with other wastewater treatment systems are also reported.Fundação para a Ciência e a Tecnologia (FCT