Sponge ball cleaning can generate an abrasion effect, which leads to an attractive increasing in both permeate flux and membrane rejection. The aim of this study was to investigate the influence of the daily sponge ball cleaning (SBC) on the performance of different UF cross-flow membrane modules integrated with a bioreactor. Two 1"-membrane modules and one 1/2"-membrane module were tested. The parameters measured and controlled are temperature, pH, viscosity, particle size, dissolved organic carbon (DOC), total suspended solids (TSS), and permeate flux. The permeate flux could be improved by 60%, for some modules, after 11 days of daily sponge ball cleaning at a transmembrane pressure of 350 kPa and a flow velocity of 4 m/s. Rejection values of all tested modules were improved by 10%. The highest permeate flux of 195 L/m2.h was achieved using a 1"-membrane module with the aid of its negatively charged membrane material and the daily sponge ball cleaning. In addition, the enhancement in the permeate flux caused by daily sponge ball cleaning improved the energy specific demand for all tested modules. The negatively charged membrane showed the lowest energy specific demand of 1.31 kWh/m3 in combination with the highest flux, which is a very competitive result.

This study presents useful methods for quantifying the volumes of water usage, wastewater generation, virtual water export, and wastewater generated by export for six relevant export industries in the Middle East and North Africa (MENA) region. These export industries are based in: Algeria, Bahrain, Egypt, Iran, Iraq, Israel, Jordan, Kuwait, Lebanon, Libya, Morocco, Oman, Palestinian Territories, Qatar, Saudi Arabia, Syria, Tunisia, and United Arab Emirates (UAE). Results show that approximately 4.26 × 10 9 m 3 of water is used per annum and approximately 1.04 × 10 9 m 3 of wastewater is generated during production by the studied industries in 2011. The difference (3.22 × 10 9 m 3 ) between the used water and generated wastewater volumes is related to water evaporation or injection underground (oil well pressure maintenance). The net virtual water export of the six studied commodities for the year 2015 from MENA to EU28 [i.e., 28 countries in the European Union] is approximately 3.0 × 10 8 m 3 , which is equivalent to approximately 7.05% of the water used by those industries. For example, Saudi Arabia represents the largest net virtual water exporter (approximately 1.25 × 10 8 m 3 ). Crude oil represents approximately 2.59 × 10 8 m 3 of the net virtual water export; fertilizers represent 6.5 × 10 7 m 3 , while pig iron and olive oil represent 3.9 × 10 5 , and 1.3 × 10 5 m 3 , respectively. The Saudi Arabian hydrological system is under the greatest pressure externally due to these exports to EU28, where the net virtual water export represents approximately 1.6% of the actual renewable water resources and desalination capacity of this country. In general, this study shows that, in terms of the grey water footprint (GWF), the pollution of water bodies caused by production (year 2011) is relevant for the crude oil, refined petroleum, and olive oil industries, whereas pollution caused by exports to EU28 countries (year 2015) is primarily related to the crude oil industry and olive oil mills. The GWFs for all the six industries caused by production and export are 111.8 × 10 9 (for the year 2011) and 18.7 × 10 9 m 3 /year (for the year 2015), respectively. One importance of the current work is that the specific water uses here could be compared to those of the same industries in developed countries. Based on these comparisons, decisions related to the need for water conservation can be made. The implementation of industrial water conservation in the MENA region could alleviate the pressure on water resources and help mitigate the water problems in the MENA. The time in which these results apply for production and export are the years 2011 and 2015, respectively.

Knowledge of the achievable product regions by rectification of multicomponent mixtures is a key factor in the design of rectification columns. On the basis of reversible rectification, a universally valid method for the identification of feasible product regions and the minimal reflux ratio is given. This method is valid for azeotropic mixtures as well as for mixtures with any number of components.

New short-cut methods providing optimal design parameters for distillation columns with simple and complex configurations including two-feed and one-feed-one-side-stream columns are presented. The methods assume constant relative volatilities and constant molar flow rates within each distillation section. The design equations are based on the Underwood equations for the calculation of minimum reflux (reboil) ratio, the analytical formulations of the distillation line, the Eigenfunction and the number of theoretical stages for each mass transfer section of the column. Furthermore, the geometrical properties of a given separation are considered. Optimization algorithms based on the minimization of the total number of theoretical stages of the column with taking into account the mass balance at each feed section have been elaborated. In comparison to the boundary value method the new short-cut methods require a minimum number of specifications; they do not need any graphical support, and provide a lower total number of theoretical stages particularly for complex configurations. The new short-cut methods have been extended to the design of columns separating azeotropic mixtures by approximating the latter by appropriate pseudo-ideal mixtures. Several separation examples for azeotropic mixtures, including different types of splits as well as columns with simple and complex configurations were tested and show a very good agreement with the simulation results obtained with Radfrac (Aspenplus).

Systematic investigations of activated sludge separation were conducted using membrane filtration. To accomplish this, different organic tubular membranes with different separation limits and diameters were examined. Furthermore, from the results obtained in the initial tests, an appropriate membrane was chosen for a long-term test. The investigations determined that for biomass separation by the tubular membranes in the tested system, neither the membrane material nor the separation limit within a range of 1μm to 20,000Da had a significant influence on the filtration characteristics. It was recognized that the application of a tubular membrane with a diameter of less than 8mm is problematic, because high flow velocities were needed to prevent blockage of the membrane. When the flow velocity was in the range of 1 to 4m/s, a linear relation between flux and velocity was found. This showed the potential for controlling the membrane filtration process and externally influencing the permeate rate. An average retention of TOC was about 75%. The retention of TOC was not significantly influenced by the nominal pore sizes of the membranes (except for the membrane WFNX 0505) which were tested here. The ultrafiltration membrane WFS 0120 (Stork) was prominent in the long-term test due to its very high flux, germfree permeate with a MWCO (molecular weight cut-off) of 100,000Da, and was not blocked with a diameter of 14.4mm, also at lower flow velocities. The results of the long-term test supported the hypothesis that a meaningful application of such a module concept is possible in a filtration plant for the preparation of samples or for the rejection of the biomass in small sewage treatment plants.

As Advanced Oxidation Processes (AOPs) are based on radical reactions that are very fast, non-selective and can completely oxidise substances, they have great potential for the removal of non-biodegradable pollutants from municipal and industrial wastewater. However, although there has been much progress in understanding AOPs, most work has been limited to laboratory or pilot-plant scale; there are few reports on industrial applications of AOP for wastewater treatment and hardly any disclose costs. Publication of such studies is needed if AOPs are to gain wide application as an alternative to more conventional treatment methods.

Different nanocrystalline photoactive TiO2 catalysts were prepared by the hydrolysis of titanyl sulphate (TiOSO4). Some important parameters in the preparation procedure, such as pH, calcination temperature, hydrolysing agent and temperature and ageing time were varied, leading to TiO2 with very different physical properties, i.e. crystalline phase composition, crystallite size, surface area, light absorption properties and bandgap energy. The photocatalytic activity of the TiO2 catalysts was evaluated using the photooxidation of dichloroacetic acid (DCA) as probe reaction. The experimental results revealed that the photocatalytic activity of the samples was greatly affected by their physical properties and therefore by the experimental conditions employed in their preparation. Using the optimum preparation parameters, TiO2 with an activity notably higher than the commercial TiO2 Degussa P-25 was obtained. Photoelectrochemical properties of both materials were studied for the hypothesis of enhanced activity.