Bioremediation of trace organic compounds found in precious metals refineries wastewaters: A review of potential options

Platinum group metal (PGM) refining processes produce large quantities of wastewater, which is contaminated with the compounds that make up the solvents/extractants mixtures used in the process. These compounds often include solvesso, β-hydroxyxime, amines, amides and methyl isobutyl ketone. A process to clean up PGM refinery wastewaters so that they could be re-used in the refining process would greatly contribute to continual water storage problems and to cost reduction for the industry. Based on the concept that organic compounds that are produced biologically can be destroyed biologically, the use of biological processes for the treatment of organic compounds in other types of waste stream has been favoured in recent years, owing to their low cost and environmental acceptability. This review examines the available biotechnologies and their effectiveness for treating compounds likely to be contained in precious metal extraction process wastewaters. The processes examined include: biofilters, fluidized bed reactors, trickle-bed bioreactors, bioscrubbers, two-phase partitioning bioreactors, membrane bioreactors and activated sludge. Although all processes examined showed adequate to excellent removal of organic compounds from various gaseous and fewer liquid waste streams, there was a variation in their effectiveness. Variations in performance of laboratory-scale biological processes are probably due to the inherent change in the microbial population composition due to selection pressure, environmental conditions and the time allowed for adaptation to the organic compounds. However, if these factors are disregarded, it can be established that activated sludge and membrane bioreactors are the most promising processes for use in the treatment of PGM refinery wastewaters

Surfactants-based remediation as an effective approach for removal of environmental pollutants—A review

Deterioration of environmental quality and equilibrium by rampant industrial expansion, accelerated urbanization and unchecked population growth has become a high-priority concern. The release of an alarming number of toxic polluting agents such as volatile organic compounds, dyes, heavy metals, pharmaceuticals, pesticides, industrial wastes, and personal care products due to natural or anthropogenic activities pose direct adverse effects on human health and living entities. This issue is inescapably increased because of the lack of efficient technologies for the proper disposal, management, and recycling of waste. It is of paramount importance to track alternative solutions to address these pollution problems for an eco-sustainable environment. Conventional remediation techniques are either inefficient, cumbersome or restricted due to certain techno-economic limitations. Environmental compatibility and high pollutant-removal efficacy make surfactants valuable for removal of organic pollutants and toxic heavy metal ions from different mediums. In this review, we present recent and up-to-date information on micelles/surfactants-assisted abatement of a vast number of toxic agents of emerging concern from water/wastewater including volatile organic compounds, personal care products, pharmaceutically active residues, toxic metals, dye pollutants, pesticides, and petroleum hydrocarbons. Based on the literature survey, it can be concluded that micelles-assisted water and soil treatment technology can have a better future on large-scale decontamination of wastewater. Though bio-surfactants are environmentally friendlier matrices and have successfully been employed for environmental decontamination; their large-scale applicability is challenging owing to high costs. Additional research efforts on the development and employment of novel bio-surfactants might render wastewater treatment technology greener, smarter and economical

Immobilization of photocatalyst on supporting materials for pollutant control

This study demonstrated facile and practical approaches of immobilizing photocatalyst powder on supporting substrates and investigated the pollutant removal performance of the obtained materials. These findings opens the opportunities for applying the photocatalytic materials for practical water and air pollutant management

Comparative Evaluation of Conventional and Innovative Biotechnologies for Odour Abatement in Wastewater Treatment Plants

Como resultado de una legislación ambiental cada vez más estricta, del acercamiento de las zonas residenciales a las Estaciones Depuradoras de Aguas Residuales (EDARs) y del aumento de las expectativas ciudadanas con respecto a los estándares de calidad ambiental exigidos a las compañías que explotan estas EDARS, el número de quejas por contaminación odorífera ha crecido de manera substancial en los últimos años. En la presente tesis se realiza una comparación sistemática de la eficacia de diferentes sistemas biológicos (tanto convencionales como innovadores: biofiltros, biofiltros percoladores, sistemas de difusión en lodos activos, bioreactores de membrana y sistemas bifásicos) en el tratamiento de emisiones odoríferas, centrándose en la fracción más hidrofóbica de estas emisiones. Además, se evalúa la influencia de parámetros clave en el rendimiento de desodorización del proceso, la estabilidad y las dinámicas microbianasDepartamento de Ingeniería Química y Tecnología del Medio Ambient

Process intervention for water recovery in food manufacture

A case study has been conducted for the recovery of water from complex wastewater at a soluble coffee manufacturing factory. The study has evaluated separation methods for process intervention based on environmental and economic assessments. Water recovery was identified in two possible wastewater streams at the factory: the overall plant effluent and an intermediate stream before it enters on-site pre-treatment. A novel vibratory field membrane separation was tested at the laboratory scale using real factory wastewater and scaled-up using appropriate design protocols. Recovery of water from the intermediate stream proved the most effective, both environmentally and economically. The full-scale vibratory membrane process recovers 100,000 gallons of water per day that meets specifications for the factory cooling tower. The proposed design reduced the daily well water with draw by 21% and the amount of wastewater discharged from the factory by 28.5%. Annual operating costs were reduced by 22.5% and total life cycle emissions were reduced by 27.8%. These reductions are mainly the result of the reduced volume of wastewater discharged from the factory and the reduced energy requirement of the on-site pre-treatment processes. The vibratory membrane process for water recovery presents favorable economics, even after capital costs are considered. The net present value after 10 years is $485,300, while the payback time is under three years

Removal of Acetone from Wastewater by POSS Loaded PDMS Membrane

The waste-water of the chemical processes includes hundreds of hazardous pollutants with low concentration. Although the emission of trace amounts of these chemicals is allowed by the laws, they are quite harmful to the water ecosystem and the human health. These chemicals including the acetone, toluene, phenol, and esters are defined as volatile organic compounds (VOCs). Separation of the VOCs from the large volume of industrial waste-water is required practically complicated and advanced processes. In this approach, more economically and efficient separation methods can be more favorable such as pervaporation. Pervaporation (PV) is an attractive and promising method for separation the small amount of dissolved chemicals from the waste-water. Pervaporative separation does not need any toxic solvent or external heat energy during the separation process. Therefore, it is defined as a cost effective and environmentally friendly process. In this study, acetone was selected as a VOC component and it was selectively separated from the model mixture (acetone-water) by pervaporation where the poly(hedral oligomeric silsesquioxane)(POSS) loaded poly(dimethyl siloxane) hydrophobic membrane was used. The structure of the membrane was characterized by scanning electron and polarized microscopy methods. The surface structure of the membrane was also analyzed by contact angle measurements. Effects of feed temperature and acetone-water concentration on separation performance were evaluated in terms of the total flux and acetone separation factor. Compared to the pristine PDMS membrane, 212% improvement on separation factor was achieved by 10 wt.% POSS incorporated membrane. The highest acetone separation factor was obtained as 237 when the temperature was 30 ºC and the acetone concentration was 1%

Air Pollutants Removal Using Biofiltration Technique: A Challenge at the Frontiers of Sustainable Environment

[Image: see text] Air pollution is a central problem faced by industries during the production process. The control of this pollution is essential for the environment and living organisms as it creates harmful effects. Biofiltration is a current pollution management strategy that concerns removing odor, volatile organic compounds (VOCs), and other pollutants from the air. Recently, this approach has earned vogue globally due to its low-cost and straightforward technique, effortless function, high reduction efficacy, less energy necessity, and residual consequences not needing additional remedy. There is a critical requirement to consider sustainable machinery to decrease the pollutants arising within air and water sources. For managing these different kinds of pollutant reductions, biofiltration techniques have been utilized. The contaminants are adsorbed upon the medium exterior and are metabolized to benign outcomes through immobilized microbes. Biofiltration-based designs have appeared advantageous in terminating dangerous pollutants from wastewater or contaminated air in recent years. Biofiltration uses the possibilities of microbial approaches (bacteria and fungi) to lessen the broad range of compounds and VOCs. In this review, we have discussed a general introduction based on biofiltration and the classification of air pollutants based on different sources. The history of biofiltration and other mechanisms used in biofiltration techniques have been discussed. Further, the crucial factors of biofilters that affect the performance of biofiltration techniques have been discussed in detail. Finally, we concluded the topic with current challenges and future prospects