Wastewater Disinfection by Ozone: Influence of Water Quality and Kinetics Modeling

Wastewater disinfection by ozone was investigated at pilot scale on different effluents. The organic matter (COD and TOC) was shown to have the biggest influence on the ozone demand of the effluents. Disinfection of fecal indicators could be modeled as the reaction on a double population. The presence of more resistant microorganisms results in the need for higher treatment doses and a tertiary filtration when the effluent has to meet the stringent Title 22 standard. Eventually, the high virucidal power of ozone makes it very attractive when viruses are targeted.     

Modification of polycaproamide fibres with ethoxylated compounds. Preparation of polycaproamide with antistatic properties

Conclusions The possibility of using diethylenetriamine which has been ethoxylated to various degrees to give antistatic properties to PCA has been discussed; the antistatic effect is expressed most strongly in the case of DETA 60.It has been found that the antistatics studied exert a regulating action on the degree of polymerization of the -caprolactam, displayed in a decrease in the molecular weight of the PCA and an increase in the LMC content of the polymer. This brought about by the fact that the products examined contain, even though in slight amounts, free amino groups. DETA 100 exerts the weakest action.Under otherwise equal conditions in PCA synthesis, the introduction of DETA increase the rate of polymerization in the initial stage of the process.In view of the effects described, it is advisable, in preparing PCA fibres, to use products which contain 60 to 80 moles of ethylene oxide.Bulgaria. Translated from Khimicheskie Volokna, No. 1, pp. 42–44, January–February, 1984.     

The role of MBR technology for the improvement of environmental footprint of wastewater treatment

This paper aims to demonstrate the relevance of membrane bioreactor (MBR) technology for the reduction of the environmental footprint of wastewater treatment in terms of removal of microbial and organic trace pollutants with increased reliability of operation. The application of a holistic approach using failure mode analysis, life cycle analysis (LCA), water quality fingerprints and environmental impacts underlines the lower environmental footprint of MBRs compared with conventional activated sludge. Several elements of this empirical approach can be included to upgrade the existing LCA tools in order to include the reduction of eco-toxicity, better human health protection and water reuse.     

Inhibiting properties and adsorption of some thioamides on mild steel in sulphuric acid solutions

The inhibiting properties and adsorption behaviour of thioacetamide (TAA), thiobenzamide (TBA) and thiocinnamamide (TCA) on mild steel in sulphuric acid solution were studied by gravimetric, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. TBA and TCA were found to be mixed type inhibitors providing good corrosion inhibition. Different mechanisms of adsorption and corrosion inhibition were observed for the tested thioamides. In the cases of TBA and TCA, the adsorption of the compounds is chemical and the values of the activation energy (Ea) and the pre-exponential factor (A) are lower than the corresponding values observed in inhibitor free solution. The adsorption of TAA is physical and the values of Ea and А are higher than the corresponding values in sulphuric acid solution. The adsorption process of TBA and TCA on the mild steel/sulphuric acid solution interface is described by Langmuir’s isotherm. A correlation between the adsorption capability and the inhibiting efficiency of the molecules and their donor–acceptor properties (E _HOMO and E _LUMO) has been established. It is ascertained that the protection effect of TAA depends on the amount of hydrolysis products.     

Microstructure and mechanical properties of P265GH cast steel after modification with TiCN particles

Particles of TiCN and TiC were produced by means of self-spreading high temperature synthesis and after covering with metal protector were studied in order to be applied for modification of molten steel. After microstructure characterization the TiCN nano- and micron-sized particles were selected for modification of castings of P265GH steel and the microstructure and mechanical properties of the modified steel were studied and compared with those of the steel without modification. The data from microstructure-properties analysis of the modified steel showed that the steel treated with nano- and micro-sized particles has significantly refined microstructure, increased strength and hardness and improved elongation in comparison with the non-modified castings.     

Preparation of polycaproamide yarns with reduced static

Conclusions Yarns with a high antistatic effect, which is stable to wet treatments, have been obtained by introducing product DETA80 into polycaproamide.DETA80 antistat causes changes in the supermolecular structure of yarns which lead to a reduction in strength and deformation properties of the yarns and to an increase in their ability to be dyed.The antistats do not exert an effect on the light-resistance of the yarns, nor on resistance of the color to set treatment.Translated from Khimicheskie Volokna, No. 5, pp. 54–55, September–October, 1984.     

On-site evaluation of the removal of 100 micro-pollutants through advanced wastewater treatment processes for reuse applications

The next challenge of wastewater treatment is to reliably remove micro-pollutants at the microgram per litre range in order to meet reuse applications and contribute to reach the good status of the water bodies. A hundred priority and relevant emerging substances were measured to evaluate at full-scale the removal efficiencies of seven advanced treatment lines (one membrane bioreactor process and six tertiary treatment lines) that were designed for reuse applications. To reliably compare the processes, specific procedures for micro-pollutants were applied for sampling, analysis and calculation of removal efficiencies. The membrane bioreactor process allowed to upgrade the removal efficiencies of about 20% of the substances measured, especially those that were partially degraded during conventional processes. Conventional tertiary processes like high rate clarification, sand filtration and polishing pond achieved significant removal for some micro-pollutants, especially for adsorbable substances. Advanced tertiary processes, like ozonation, activated carbon and reverse osmosis were all very efficient to complete the removal of polar pesticides and pharmaceuticals; metals and less polar substances were better retained by reverse osmosis.     

Electrochemical study of the adsorption and inhibiting properties of halogen derivatives of aniline on iron in sulfuric acid

The adsorption of halogen derivatives of aniline on an iron electrode in sulfuric acid medium has been studied in relation to their inhibiting properties using electrochemical a.c. impedance and d.c. polarization techniques, as well as quantum chemical calculations of chemical structure and distribution of electron charges in the organic molecules. It is established that the adsorption process is described by Frumkin's isotherm. The adsorption parameters characterizing the interaction forces between the molecules in the adsorbed layer, the free energy of adsorption, the maximum surface excess of adsorbed species, the area occupied by each molecule etc. have been calculated on the basis of this isotherm. It is shown that the inhibition efficiency, as well as the free energy of adsorption, increases in the sequence: aniline < p-Cl-aniline < p-Br-aniline < p-I-aniline. It was found that the adsorption behaviour of the substances studied is characterized by two adsorption states: vertical and planar orientation of the molecules. Combining data from electrochemical measurements with data from quantum chemical calculations the correlation between the chemical structure of the aniline derivatives and their adsorption capability and inhibition efficiency has been ascertained.     

Development of a hybrid ozonation biofilm-membrane filatration process for the production of drinking water.

Drinking water sources in Norway are characterized by high concentrations of natural organic matter (NOM), low alkalinity and low turbidity. The removal of NOM is therefore a general requirement in producing potable water. Drinking water treatment plants are commonly designed with coagulation direct filtration or NF spiral wound membrane processes. This study has investigated the feasibility and potential of a hybrid process combining ozonation and biofiltration with a rotating disk membrane for treating drinking water with high NOM concentrations. Ozonation will oxidize the NOM content removing colour and form biodegradable organic compounds, which can be removed in biological filters. A constructed water was used in this study which is representative of ozonated NOM-containing water. A rotating membrane disk bioreactor downstream the ozonation process was used to carry out both the biodegradation as well as biomass separation in the same reactor. Maintenance of biodegradation of the organic matter while controlling biofouling of the membrane and acceptable water production rates was the focus in the study. Three operating modes were investigated. Removal of the biodegradable organics was consistent throughout the study indicating that sufficient biomass was maintained in the reactor for all operating conditions tested. Biofouling control was not achieved through shear-induced cleaning by periodically rotating the membrane disks at high speed. By adding a small amount of sponges in the membrane chamber the biofouling could be controlled by mechanical cleaning of the membrane surface during disk rotation. The overall results indicate that the system can favorably be used in an ozonation/biofiltration process by carrying out both biodegradation as well as biomass separation in the same reactor.