- Preparation of carboxymethyl-quaternized oligochitosan and its scale
inhibition and antibacterial activity
- Authors: Hui-xin Zhang; Dong-xue Sun, Yu-chao Zhu, Ting-ru Yang, Xiu-hong Jin Feng Wang
Abstract: Carboxymethyl-quaternized oligochitosan (CMQAOC) was prepared through carboxymethylization and N-quaternization of oligochitosan (OC) which was obtained from chitosan degradation. The structure was confirmed by Fourier transform infrared spectroscopy (FT-IR), 1H-NMR, and X-ray diffraction (XRD) analysis. The performances for both scale and microbial inhibition of CMQAOC were evaluated by static test and culture flask method, respectively. The results showed that the scale inhibition rate for calcium carbonate and calcium sulfate scale were both beyond 80% with a CMQAOC dosage of 20 mg/L. With a degree of substitution for quaternary ammonia of up to 0.74, the killing rate for saprophytic bacteria and sulfate-reducting bacteria was 98.9 and 100%, respectively. The ratio of biochemical oxygen demand/chemical oxygen demand (BOD5/COD) of CMQAOC was 0.45, showing that CMQAOC is as biodegradable as OC.
- Impact of operating conditions on performance of capacitive deionisation
for reverse osmosis brine recovery
- Authors: Jing Yu; Jianjun Qin, Kiran A. Kekre, Balakrishnan Viswanath, Guihe Tao Harry Seah
Abstract: The study aimed at further developing an integrated capacitive deionisation (CDI)-based process to treat reverse osmosis (RO) brine from a water reclamation facility to increase the overall water recovery to more than 90% and to achieve a sustainable operation of the process with optimised conditions. The normalised treatment capacity of CDI membranes and voltage was optimised at 24.8 L/m2/h and 1.1–1.5 V, respectively. The operation time of CDI cell with membrane area of 0.8 m2 was able to be extended to more than 1,000 h from the initial 72 h. Cleaning with both HCl at low pH and salt solution was good in removing foulants but cleaning with citric acid was not effective, as expected. The initiative cleaning strategy was found to be more effective in CDI fouling control and is recommended for long-term CDI operation. CDI cell efficiency for removal of ions reduced with operation time due to cleaning with surfactants at pH 10.5 which should be avoided in a future study.
- Mechanistic study of Cd adsorption through esterification and acetylation
of novel biosorbent Gallus Domesticus chemically modified biomaterial for
- Authors: Aliya Fazal; Uzaira Rafique
Abstract: The inevitable expansion of industries for development is at the cost of release of industrial pollutants into the natural reservoirs of the environment. Biosorption is becoming an important component in the integrated approach to the treatment of aqueous effluents. The adsorption properties of Gallus Domesticus are determined as a function of batch operating conditions including contact time, solution initial concentration and temperature. Metal ion fixed Fourier transform infrared spectroscopy spectrum depicted amine, alcohol, carboxyl, and carbonate ion as active sites for metal sorption. Augmentation of removal capacity to 5 and 17% is tailored by esterification and acetylation of different surface functional groups of the base matrix. Kinetics is dissected through diffusion-based kinetic models, and best fit was figured out for Elovich equation. The thermodynamic relationship draws that enthalpy (ΔH° 45.48 KJ/mol) and entropy (ΔS° 153.32 J/mol K) are positive and entropy of the system is much larger than enthalpy. Results propose alteration of domestic waste into economical adsorbent for commercialization with no processing in the efficient removal of cadmium from wastewater.
- Treatment of municipal landfill leachate using magnetic porous ceramsite
- Authors: Yue Cheng; Lei Guo
Abstract: In this study, porous ceramsite carrier was modified using magnetic material as raw material. The magnetic porous ceramsite carrier was applied to the treatment of municipal landfill leachate. The results showed that the removal efficiency of chemical oxygen demand (COD), NH3-N and Cr6+ in the supernatant were all more than 90% after 30 days with the aeration rate of 3 L/h, the aeration time of 16 h/d and the temperature of 20–30 °C. The output concentration met the national life Landfill Pollution Control Standard (PR China GB16889-2008) requirements. The magnetic properties significantly improved the carrier biofilm formation, compared with the conventional activated sludge process and non-magnetic carrier. The COD, NH3-N and Cr6+ removal efficiency were 5–10%, 5–7% and 5–10%, respectively.
- Feasibility assessment of pervaporation for desalinating high-salinity
- Authors: Emily Huth; Satish Muthu, Luke Ruff Jonathan A. Brant
Abstract: Pervaporation, which is a non-pressure driven membrane process, was evaluated to determine its viability for desalinating high-salinity source waters like those originating from oil and natural gas development (produced water). Two types of membrane material chemistries were studied in order to identify the optimal properties for maximizing the permeate flux under a given set of operating conditions. Permeate flux was determined to be a significant function of membrane thickness and the diffusion coefficient of water through the membrane. The diffusion coefficient is in turn a function of the membrane's affinity for water (hydrophilicity) and its fractional free volume space. A cellulose triacetate membrane (Membrane B) achieved fluxes of 0.06 m3m–2day–1 when treating solutions having salt concentrations of 100 g L–1, comparable to fluxes achieved by other types of non-pressure driven membrane processes. The flux increased in a linear fashion with decreasing ionic strength and improved through increases in the vapor pressure gradient and/or inclusion of a feed channel spacer into the test cell. Salt rejection efficiencies by all membranes were >99%; however, co-ions were able to penetrate into the membrane material matrix over time.
- Filter backwash water treatment options
- Authors: S. Arendze; M. Sibiya
Abstract: Filtration acts as the final step in the removal of suspended matter and protozoa. The accumulated residue is removed during the backwash process and any subsequent recycling of filter backwash water could potentially re-introduce these contaminants into the main treatment process. By separating the filter backwash water from the main treatment process, factors that could interfere with the integrity of the primary treatment barriers, will be eliminated. Treatment and recovery of the filter backwash water would be beneficial in terms of water reuse, by replacing a proportion of the freshwater demand. The aim of this study was to investigate possible treatment options for the filter backwash water at Rand Water. Treatment options for filter backwash water treatment plants usually consist of a solids removal process and a disinfection process. Three solid removal processes for filter backwash water from Rand Water's filtration systems were selected for testing on an experimental basis: (1) sedimentation without flocculation, (2) sedimentation with flocculation, and (3) dissolved air flotation with flocculation. Flocculation with sedimentation produced the best results when compared to the other two treatment options evaluated. It is a simple and effective option for the treatment of filter backwash water.
- The use of treated wastewater and fertigation in greenhouse pepper crop as
affecting growth and fruit quality
- Authors: Eleni Dagianta; Dimitrios Goumas, Thrassyvoulos Manios Nikos Tzortzakis
Abstract: The performance and suitability of tertiary treated wastewater (TW) and/or fertigation (F) in pepper plants were studied over a 4-month period in greenhouse conditions. Four treatments were used consisting of (1) water, (2) water + F, (3) TW, and (4) TW + F. The F and/or TW application increased plant height and plant biomass compared with the control plants (irrigated with water) while no differences were observed in the number of leaves produced. Plants grown with TW + F were thicker than control plants. The addition of F increased fruit number in both water and TW, which resulted in increased plant yield and fruit marketability for the water application but decreased mean fruit weight for TW application. The application of TW increased fruit total soluble solids but decreased fruit firmness whereas adding F, these changes were normalized. The F and/or TW application reduced fruit total phenolics, fruit acidity, and fruit length but not fruit diameter. No differences were observed in fruit dry matter content, fruit color/lightness (a, b, and L value). Bacteria (total coliform and Escherichia coli) units on the fruits did not differ among the treatments. The results indicate that wastewater may act as an alternative means of irrigation if following strict safety aspects while the fertigation acted beneficially.