The impact of ozone treatment on the removal effectiveness of various refractory compounds in wastewater from petroleum refineries.

Large volumes of wastewater are generated during petroleum refining processes. Petroleum refinery wastewater (PRW) can contain highly toxic compounds that can harm the environment. These toxic compounds can be a challenge in biological treatment technologies due to the effects of these compounds on microorganisms.

Modeling adsorption and photocatalytic treatment of recalcitrant contaminant on multi-walled carbon/TiO nanocomposite.

A nanocomposite photocatalyst consisting of titanium dioxide (TiO) supported on multiwalled carbon nanotubes (MWCNTs) has been successfully prepared and used for the treatment of wastewater contaminated with tetracycline (TC), a recalcitrant antibiotic pollutant. The TiO/MCNT composites were prepared by a simple evaporation-drying method. The properties of MWCNT/TiO were optimized by dispersing different amounts of TiO onto MWCNT.

Synthesis of bismuth oxyhalide (BiOBr I ) solid solutions for photodegradation of methylene blue dye.

The removal of textile wastes is a priority due to their mutagenic and carcinogenic properties.  In this study, bismuth oxyhalide was used in the removal of methylene blue (MB) which is a textile waste. The main objective of this study was to develop and investigate the applicability of a bismuth oxyhalide (BiOBr I ) solid solutions in the photodegradation of MB under solar and ultraviolet (UV) light irradiation.

Modeling ozonation pretreatment parameters of distillery wastewater for improved biodegradability.

In this study, ozonation pretreatment of real distillery wastewater (DWW) for biodegradability enhancement was undertaken. Response surface methodology was used to model the value of effective parameters, including ozonation duration and initial chemical oxygen demand (COD) concentration, and to estimate linear interactions and quadratic effects. The analysis of variance confirmed the adequate description of all the responses by the quadratic model employed.

Fixed-bed operation for manganese removal from water using chitosan/bentonite/MnO composite beads.

In the present study, a new composite adsorbent, chitosan/bentonite/manganese oxide (CBMnO) beads, cross-linked with tetraethyl-ortho-silicate (TEOS) was applied in a fixed-bed column for the removal of Mn (II) from water. The adsorbent was characterised by scanning electron microscopy (SEM), Fourier transform infra-red (FT-IR), N adsorption-desorption and X-ray photoelectron spectroscopy (XPS) techniques, and moreover the point of zero charge (pH) was determined. The extend of Mn (II) breakthrough behaviour was investigated by varying bed mass, flow rate and influent concentration, and by using real environmental water samples.

Photocatalytic degradation of P-Cresol using TiO/ZnO hybrid surface capped with polyaniline.

This study evaluated the photocatalytic activity of polyaniline (PANI)-capped titanium dioxide and zinc oxide (TiO/ZnO) hybrid, for the degradation of P-Cresol. The hybrid was synthesized by precipitating ZnO on the surface of commercial TiO. An "in situ" chemical oxidative polymerization method was used to prepare the PANI capped hybrid (TiO/ZnO/PANI).

Ultraviolet and solar photocatalytic ozonation of municipal wastewater: Catalyst reuse, energy requirements and toxicity assessment.

The present study evaluated the treatment of municipal wastewater containing phenol using solar and ultraviolet (UV) light photocatalytic ozonation processes to explore comparative performance. Important aspects such as catalyst reuse, mineralization of pollutants, energy requirements, and toxicity of treated wastewater which are crucial for practical implementation of the processes were explored. The activity of the photocatalysts did not change significantly even after three consecutive uses despite approximately 2% of the initial quantity of catalyst being lost in each run.

Batch equilibrium and kinetics of mercury removal from aqueous solutions using polythiophene/graphene oxide nanocomposite.

Polythiophene/graphene oxide (PTh/GO) nanocomposite (NC) was prepared through polymerisation of thiophene in the presence of GO and was used for mercury ions (Hg) adsorption in aqueous solutions. Equilibrium studies showed that mercury removal was strongly influenced by solution pH and GO composition in the NC. The equilibrium data were well described by both Langmuir and Freundlich isotherm models, with a Langmuir maximum adsorption capacity of 113.

Evaluation of synergy and bacterial regrowth in photocatalytic ozonation disinfection of municipal wastewater.

The use of solar and ultraviolet titanium dioxide photocatalytic ozonation processes to inactivate waterborne pathogens (Escherichia coli, Salmonella species, Shigella species and Vibrio cholerae) in synthetic water and secondary municipal wastewater effluent is presented. The performance indicators were bacterial inactivation efficiency, post-disinfection regrowth and synergy effects (collaboration) between ozonation and photocatalysis (photocatalytic ozonation). Photocatalytic ozonation effectively inactivated the target bacteria and positive synergistic interactions were observed, leading to synergy indices (SI) of up to 1.

Photodecolorisation of melanoidins in vinasse with illuminated TiO-ZnO/activated carbon composite.

A hybrid photo-catalyst, TiO-ZnO, was synthesized by immobilizing ZnO on commercial TiO (aeroxide P25). Activated carbon (AC) was subsequently used to support the hybrid, thus forming a TiO-ZnO/AC composite catalyst. Fourier transform infrared (FTIR) analysis and scanning electron microscopy integrated with energy-dispersive X-ray spectroscopy (SEM-EDX) investigations revealed successful catalyst synthesis.

A critical review on factors influencing fermentative hydrogen production.

Biohydrogen production by dark fermentation of different waste materials is a promising approach to produce bio-energy in terms of renewable energy exploration. This communication has reviewed various influencing factors of dark fermentation process with detailed account of determinants in biohydrogen production. It has also focused on different factors such as improved bacterial strain, reactor design, metabolic engineering and two stage processes to enhance the bioenergy productivity from substrate.

Impact of ozonation in removing organic micro-pollutants in primary and secondary municipal wastewater: effect of process parameters.

The study investigates the influence of process parameters on the effectiveness of ozonation in the removal of organic micro-pollutants from wastewater. Primary and secondary municipal wastewater containing phenol was treated. The effect of operating parameters such as initial pH, ozone dosage, and initial contaminant concentration was studied.

Application of mucilage from Dicerocaryum eriocarpum plant as biosorption medium in the removal of selected heavy metal ions.

The ability of mucilage from Dicerocaryum eriocarpum (DE) plant to act as biosorption medium in the removal of metals ions from aqueous solution was investigated. Functional groups present in the mucilage were identified using Fourier transform infrared spectroscopy (FTIR). Mucilage was modified with sodium and potassium chlorides.

Modelling energy efficiency of an integrated anaerobic digestion and photodegradation of distillery effluent using response surface methodology.

Anaerobic digestion (AD) is efficient in organic load removal and bioenergy recovery when applied in treating distillery effluent; however, it is ineffective in colour reduction. In contrast, ultraviolet (UV) photodegradation post-treatment for the AD-treated distillery effluent is effective in colour reduction but has high energy requirement. The effects of operating parameters on bioenergy production and energy demand of photodegradation were modelled using response surface methodology (RSM) with a view of developing a sustainable process in which the biological step could supply energy to the energy-intensive photodegradation step.

Combined anaerobic digestion and photocatalytic treatment of distillery effluent in fluidized bed reactors focusing on energy conservation.

Anaerobic digestion (AD) can remove substantial amount of organic load when applied in treating distillery effluent but it is ineffective in colour reduction. Conversely, photodegradation is effective in colour reduction but has high energy requirement. A study on the synergy of a combined AD and ultra violet (UV) photodegradation treatment of distillery effluent was carried out in fluidized bed reactors to evaluate pollution reduction and energy utilization efficiencies.

An integrated anaerobic digestion and UV photocatalytic treatment of distillery wastewater.

Anaerobic up-flow fixed bed reactor and annular photocatalytic reactor were used to study the efficiency of integrated anaerobic digestion (AD) and ultraviolet (UV) photodegradation of real distillery effluent and raw molasses wastewater (MWW). It was found that UV photodegradation as a stand-alone technique achieved colour removal of 54% and 69% for the distillery and MWW, respectively, with a COD reduction of <20% and a negligible BOD reduction. On the other hand, AD as a single treatment technique was found to be effective in COD and BOD reduction with efficiencies of above 75% and 85%, respectively, for both wastewater samples.

Removal of fluoride ions from aqueous solution at low pH using schwertmannite.

Wastewater containing fluoride requires polishing after precipitation/coagulation treatment in order to meet stringent environmental legislation. Accordingly, adsorption characteristics of fluoride onto schwertmannite adsorbent were studied in a batch system with respect to changes in initial concentration of fluoride, equilibrium pH of sample solution, adsorbent dosage and co-existing ions. Equilibrium adsorption data were obtained at 295.

Adsorption equilibrium modeling and solution chemistry dependence of fluoride removal from water by trivalent-cation-exchanged zeolite F-9.

Fluoride in drinking water above permissible levels is responsible for human dental and skeletal fluorosis. In this study, therefore, the large internal surface area of zeolite was utilized to create active sites for fluoride sorption by exchanging Na+-bound zeolite with Al3+ or La3+ ions. Fluoride removal from water using Al3+- and La3+-exchanged zeolite F-9 particles was subsequently investigated to evaluate the fluoride sorption characteristics of the sorbents.

Biological treatment of mixed industrial wastewaters in a fluidised bed reactor.

A study has been carried out on the operating parameters that influence the biodegradation of petroleum and brewery wastewaters, with a low-density biomass support. The biodegradation rate of a mixture of two wastes was compared with that of the separate wastes. A low aspect ratio reactor was employed, and this made it possible to operate at low superficial gas and liquid velocities.

Brewery wastewater treatment in a fluidised bed bioreactor.

A hydrodynamic characteristic performance of a three phase fluidised bed bioreactor has been studied with brewery wastewater. The influence of operating parameters, such as phase hold up, phase mixing, aspect ratio and superficial gas velocity, on an aerobic biodegradation in a bioreactor of 0.16 m i.