Browsing by Author "Hoinkis, Jan"

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Development of membrane bioreactor (MBR) process applying novel low fouling membranes
(2013-11-12) Deowan, Shamim Ahmed; Drioli, Enrico; Molinari, Raffaele; Figoli, Alberto; Hoinkis, Jan
Water is a part and parcel of human life. Water contaminated from industry and agriculture with heavy metal ions, pesticides, organic compounds, endocrine disruptive compounds, nutrients (phosphates, nitrates, nitrites) has to be effi-ciently treated to protect humans from being intoxicated with these compounds or with bacteria. Clean water as basis for health and good living conditions is too far out of reach for the majority of the population in the world (Bionexgen, 2013). Water recycling is now widely accepted as a sustainable option to re-spond to the general increase of the fresh water demand, water shortages and for environmental protection. Water recycling is commonly seen as one of the main options to provide remedy for water shortage caused by the increase of the water demand and draughts as well as a response to some economical and environmental drivers. The main options for wastewater recycling are industri-al, irrigation, aquifer recharge and urban reuse (Pidou, M., 2006). Among the industrial wastewaters, the textile industry is long regarded as a water intensive sector, due to its high demand of water for all parts of its pro-cedures. Accordingly, textile wastewater includes quite a large variety of con-tents, chemicals, additives and different kinds of dyestuffs. The main environ-mental concern with this waste water is about the quantity and quality of the water discharged and the chemical load it carries. To illustrate, for each ton of fabric products, 20 – 350 m3 of water are consumed, which differs from the color and procedure used. The quality of the textile wastewater depends much on the employed coloring matters, dyestuffs, accompanying chemicals, as well as the process itself (Brik et al., 2006). MBR technology is recognised as a promising technology to provide water with reliable quality for reuse. It provides safely reuse water for non-potable use. But the treated textile wastewater by MBR technology alone can’t comply with the reuse or discharge standard in many countries due to its colouring matters and dyestuffs remained in the effluent, if otherwise, MBR is associated with other technology like NF, RO, other processes or the applied membrane is modified or a novel MBR is applied. Fouling is another limiting factor for worldwide application of MBR technology especially in high-strength industri-al wastewater like textile wastewater. Moreover, membrane fouling is regarded as the most important bottleneck for further development of MBR technology. It is the main limitation for faster development of this process, particularly when it leads to flux losses that cleaning cannot restore (Howell et al. 2004). In this thesis work, a novel membrane bioreactor (MBR) process was devel-oped by modifying a applied commercial PES UF membrane in MBR module by nano-structured novel coating through polymerisable bicontinuous micro-emulsion (PBM) process with the purpose of having higher hydrophilicity and low fouling propensity. Before starting the MBR experiments, some characteri-sation tests such as SEM, AFM images analysis, roughness measurements, pore geometry, contact angel, standard salt rejections, model textile dye rejec-tions were performed. In addition, fouling tests using two laboratory cross flow testing units were conducted as well. To reach the ultimate goal of research, 6 sheets of novel coated membranes with size of 30 cm × 30 cm were prepared and these were used to prepare a three-envelope MBR module of 25 cm × 25 cm in size (total membrane area 0.33 m2) similar to that of a commercially available three-envelope PES UF MBR module. This novel MBR module was tested in a submerged lab-scale MBR pilot plant (tank volume ca. 60 L) for about 6 months using model textile dye wastewater (MTDW) as test media for all experiments with the aim of having uniform compositions with respect to time. The tests were done based on carefully selected operation conditions. Prior to testing of the novel membrane module MBR, experiments were carried out with a commercial PES UF MBR module using the same pilot plant set up and the same selected operating conditions for about 10 months. After comple-tion of trials with the novel coated MBR module, similar experiments were carried out again with a commercial PES UF MBR module to check the simi-larity of the biological sludge conditions and other operation conditions as well. In short, the sequences of the experiments were as follows: Commercial PES UF MBR (10 months) →novel membrane coated MBR (6 months)→PES UF MBR (1.5 months) The ultimate goal of the experiments was to compare the results between the commercial MBR and novel coated MBR module in order to demonstrate im-provement regarding fouling propensity and permeate water quality. The performance analysis shows that the novel coated MBR module compared to the commercial MBR module has 7% points higher COD removal efficien-cy, 20% points higher blue dye removal efficiency, high antifoul-ing/antimicrobial properties, resulting in a very low-fluctuating and highly ro-bust MBR process which looks promising with regard to economic viability. Since the newly developed MBR module worked excellent on laboratory scale it consequently should be deployed at an industrial site to be tested with real ii wastewater. Therefore, this novel three-envelope MBR module is on the way to be tested with real wastewater in a textile factory in Tunisia. The findings of these on-site pilot trials will serve as a basis for further improvement and even-tually pilot trails with larger membrane area will be addressed
Experimental investigation of system performance for combined desalination processes with membrane capacitive deionisation (MCDI)
(Università della Calabria, 2021-10-31) Cañas Kurz, Edgardo E.; Critelli, Salvatore; Gabriele, Bartolo; Figoli, Alberto; Hoinkis, Jan
The water supply in many coastal regions worldwide is affected by progressive salinization. Here, the use of desalination technologies is a viable solution for obtaining freshwater. In this thesis, two modular concepts for brackish water (BW) desalination by the use of membrane capacitive deionization (MCDI) and low-pressure reverse osmosis (LPRO) were developed and tested at laboratory and pilot-scales with two pilot plants installed in Vietnam. The two concepts were developed by using computer-based calculations (software: WAVE) and evaluated in a socioeconomic and environmental multi-criteria analysis. The first plant consisting of subsurface arsenic removal (SAR) as pre-treatment and MCDI for desalination was installed in Tra Vinh, in the Mekong Delta for the treatment of arseniccontaminated groundwater with a concentration of total dissolved solids (TDS) of 1.65 g/L. Results showed the feasibility of the modular concept for producing drinking water (TDS<0.45 g/L) with a specific energy consumption (SEC) of <3 kWh/m³. The relationship between feed salinity and specific ion removal of the MCDI was evaluated in real environment and compared with laboratory experiments. The use of renewable energies such as solar and wind for autonomous supply was proven feasible for these technologies. The second pilot plant was installed in a riverine estuary in the region of Cần Giờ, where no access to freshwater is available due to the progressive salinization of river water and groundwater. Here, river water showed TDS concentrations of up to 25 g/L. The combined system consisted of UF pre-treatment, LPRO and MCDI to produce drinking water and product water with TDS of <0.45 g/L and <1.5 g/L, respectively with a total SEC of 5.8 kWh/m³. Additionally, the performance of the LPRO was compared to seawater-RO (SWRO) in pilot trials, which showed a SEC of 5.5 kWh/m³. Although the SEC of single-stage SWRO was lower, the separate production of drinking and product water by LPRO+MCDI showed different advantages including a reduced SEC of 5.2 kWh/m³ for product water and additional 0.6 kWh/m³ for drinking water. Finally, an optimization of the LPRO+MCDI can be possible by increasing the desalination efficiency of the MCDI, increasing the efficiency of LPRO-pump and the MCDI power supply, and by aiming at feed water qualities with lower salinity.
Theoretical Models for Membrane Capacitive Deionization for the design of Modular Desalination Processes
(Università della Calabria, 2021-12-08) Hellriegel, Ulrich; Critelli, Salvatore; Gabriele, Bartolo; Figoli, Alberto; Hoinkis, Jan
Due to climate change, water scarcity will be exacerbated around the globe. To increase the water availability in regions at risk, water desalination plants can be a solution. Especially in rural areas, energy e cient technologies are needed so that an operation with renewable energy as photovoltaic modules can be feasible. Recent publications showed that the novel technology membrane capacitive deionization (MCDI) can achieve a lower speci c energy consumption (SEC) than reverse osmosis (RO), for brackish water desalination with salt concentrations below 2.5 g L-1. There is still a gap in research between laboratory operation and applied commercial scaled desalination, regarding experimental but also theoretical model studies. Therefore the latter is elaborated in the present PhD thesis. Hereby, existing models are reviewed, adapted and further developed to t to applied MCDI operation for drinking water production. Two dimensional nite element methods (FEM) modelling of ion transport, according to the Gouy-Chapman-Stern theory for electrical double layers (EDL) as well as computational uid dynamics (CFD) is combined with an adjusted semi-analytical modi ed Donnan (mD) model, with a constant excess chemical potential att = 2:33 kT, for the electrosorption of ions into porous active carbon electrodes. It predicts the e uent salt concentration time-dependently for di erent inputs of applied electrical currents Icell and voltages as well as inlet concentrations and volume ows. Applied MCDI operation was optimized for drinking water production with practical experiments, which support the evaluation of the theoretical ndings. The model ts to experimental data for Icell = 20 A, however the equations for the voltage over the electrodes need to be re-assessed so that the model ts for further input parameters. A CFD model of the water ow through large scaled MCDI modules (> 50 pairs of electodes) shows the need of constructing spacer thicknesses Sp small enough, to ensure equal retention times of the water between the electrodes in the module, which is important for stable diluate concentrations. Furthermore, an analytical calculation tool is developed, by adjusting the mD model and introducing an e ective salt adsorption capacity 􀀀salt; , to predict the maximum e cient charging time tmax,ch, removal- and recovery rate as well as SEC values for optimized operation of applied MCDI processes. The model reaches an accuracy of 87% for the prediction of salt removal, 86% for tmax,ch and 75% for SEC values, compared with an experimental study and thus can be used to optimize the process design of applied MCDI desalination plants.