Identification of Prodominant Microorganisms of Biotrickling Filters to Treat Polluted Air with Formaldehyde and Ethanol

Introduction: Identification of degrading microorganisms of toxic materials is regarded as an important step to complete air treatment systems. Effective microorganisms in treatment and elimination of pollutants seems to be different depending on the type of pollutants as well as environmental conditions. Identification of these microorganisms can determine optimum conditions for the system performance and the maximum efficiency can be reached. Moreover, biotechnological methods can strengthen the microorganisms to treat the pollutants. This study aimed to identify the predominant microorganisms at two biotrickiling filters that formaldehyde was used in one and ethanol  in another as the sole carbon source. Methods: In this study, two biotrickling filter pilots were made at the laboratory scale. These microorganisms were inoculated and adapted within three months. Then biotrickling filters were studies for a long time. At the end of experiments, biofilm samples were taken from biotrickling filters and predominant microorganisms were identified via microbiology studies.   Results: The results of the present study managed to identify such microorganisms as Salmonella Bongori, Pneumonia, Subspecies Pneumonia, Klebsiella Terrigena, etc. at different parts of both biotrickling filters. Conclusion: Microbial species can be widely changed with operating of  biotrickling filters at different conditions. Identifying active microorganisms in each biotrickling filter can lead to detecting optimum conditions as well as the risks caused by transfer of  the filters'  available microorganisms to the human body

Perspectives of phytoremediation using water hyacinth for removal of heavy metals, organic and inorganic pollutants in wastewater

The development of eco-friendly and efficient technologies for treating wastewater is one of the attractive research area. Phytoremediation is considered to be a possible method for the removal of pollutants present in wastewater and recognized as a better green remediation technology. Nowadays the focus is to look for a sustainable approach in developing wastewater treatment capability. Water hyacinth is one of the ancient technology that has been still used in the modern era. Although, many papers in relation to wastewater treatment using water hyacinth have been published, recently removal of organic, inorganic and heavy metal have not been reviewed extensively. The main objective of this paper is to review the possibility of using water hyacinth for the removal of pollutants present in different types of wastewater. Water hyacinth is although reported to be as one of the most problematic plants worldwide due to its uncontrollable growth in water bodies but its quest for nutrient absorption has provided way for its usage in phytoremediation, along with the combination of herbicidal control, integratated biological control and watershed management controlling nutrient supply to control its growth. Moreover as a part of solving wastewater treatment problems in urban or industrial areas using this plant, a large number of useful byproducts can be developed like animal and fish feed, power plant energy (briquette), ethanol, biogas, composting and fiber board making. In focus to the future aspects of phytoremediation, the utilization of invasive plants in pollution abatement phytotechnologies can certainly assist for their sustainable management in treating waste water

Formaldehyde removal mechanisms in a biotrickling filter reactor

Formaldehyde (FA) is one of toxic, mutagen, suspected carcinogen and teratogen pollutants presented in contaminated air and might be commonly released from a wide range of the industrial activities. Even though many studies have been made to remove FA from synthetic contaminated air stream (SCAS) using a biotrickling filter reactor (BTFR), the mechanisms of FA removal by a BTFR treatment process must to be verified. The aim of this study was to perform the laboratory-scale BTFR experiments to remove FA from the SCAS during a period of 21 days after passing an adaptation phase of 90 days. The mechanisms of FA removal from SCAS in biofilter must pass through two successive stages: (1) the first diffuses FA from gas phase to aqueous phase to form formic acid and methanol and (2) the second guarantees that the predominant microorganisms are able to metabolise the chemicals-derived FA from aqueous phase for growth and maintenance of life. The research findings may lead to better understanding of the BTFR design and operations to reduce air pollutants in order to maintain or improve air quality

Gaseous emissions of landfill and modeling of their dispersion in the atmosphere of Shahrekord, Iran

Anaerobic biodegradation of municipal solid waste produces a large amount of air pollutants. Therefore, it is important to estimate the quality and quantity of emitted pollutants from landfills worldwide. The aim of this study is to predict the amount of methane, carbon dioxide, carbon monoxide and non-methane organic compounds emitted from the Shahrekord, Iran landfill. The LandGEM model, introduced by the US Environmental Protection Agency, was utilized to predict the amount of the above-mentioned gases. Additionally, the AERMOD View model was used to estimate the dispersion of emitted pollutants from the Shahrekord landfill into the atmosphere. Metrological data, the most basic requirement enabling the models to work, were collected from the Islamic Republic of Iran Meteorological Organization. Results showed that the maximum amount of methane, carbon dioxide, carbon monoxide and non-methane organic compounds will be emitted from Shahrekord landfill in 2021. It is also elaborated that 114 million m3 of methane will be emitted between 1997 and 2023, with the potential to generate 188100MW electrical energy. The modeling of pollutants' dispersion into the atmosphere shows that concentration of the pollutants emitted by the landfill was within permissible levels in the city of Shahrekord

An overview of biological processes and their potential for CO2 capture

The extensive amount of available information on global warming suggests that this issue has become prevalent worldwide. Majority of countries have issued laws and policies in response to this concern by requiring their industrial sectors to reduce greenhouse gas emissions, such as CO2. Thus, introducing new and more effective treatment methods, such as biological techniques, is crucial to control the emission of greenhouse gases. Many studies have demonstrated CO2 fixation using photo-bioreactors and raceway ponds, but a comprehensive review is yet to be published on biological CO2 fixation. A comprehensive review of CO2 fixation through biological process is presented in this paper as biological processes are ideal to control both organic and inorganic pollutants. This process can also cover the classification of methods, functional mechanisms, designs, and their operational parameters, which are crucial for efficient CO2 fixation. This review also suggests the bio-trickling filter process as an appropriate approach in CO2 fixation to assist in creating a pollution-free environment. Finally, this paper introduces optimum designs, growth rate models, and CO2 fixation of microalgae, functions, and operations in biological CO2 fixation

Role of microalgal biotechnology in environmental sustainability-a mini review

Sustainability is a main rule in environmental resource management, and it included operational productivity, minimization of natural effect and socio-economic contemplations; which are all related. Many research projects have been conducted on finding alternative of energy from renewable sources and utilization of waste materials. Based on the previous studies one of the most environmentally friendly and sustainable methods for biofuel sources is using microalgae for the production of lipids and wastewater as its nutrient source. Microalgae are maintainable sources of biomass for fuel, food, and feed likewise as contaminant elimination from wastewater. Light, CO2, and inorganic nutrients like nitrogen and phosphorous are vital for microalgae growth. The aim of this study is thus to introduce an optimum conditions of microalgae cultivation for nutrient removal from wastewater which may impact the bioenergy production like biodiesel production. Utilizing wastewater is a common method to reduce environmental impacts, recycle water and nutrients, and decrease the volume of wastewater being transported and treated. Therefore, developing microalgae production systems would help reduce greenhouse gas emissions by capturing CO2 and producing an alternative for fossil fuels would be valuable and sustainable

Biotreatment of formaldehyde-contaminated air in a trickle bed bioreactor

A biofilm developed on polyurethane packing in a trickle bed bioreactor was used to effectively remove formaldehyde from contaminated air. Formaldehyde removal depended on the retention time of the gas in the bed as well as on the gas-liquid mass transfer coefficient. Both retention time and the mass transfer coefficient depended on the gas flow rate. At 25±1°C and pH 7, a 99% removal of formaldehyde from air with an initial contamination level of 450 mg L -1 was achieved at a hydraulic retention time of 132 s. The degradation rate was likely limited by oxygen mass transfer. The bioreactor could be operated stably over the pH range of 5 to 7 at 25±1°C. Formaldehyde removal in the bioreactor was mathematically modeled to facilitate design and scale up. The model was shown to agree well with the experimental data. Trickle bed bioreactors offer a potentially viable option for cleaning air streams contaminated with formaldehyde