Mohanadoss Ponraj

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.

Thermal comfort of various building layouts with a proposed discomfort index range for tropical climate

Recent years have seen issues related to thermal comfort gaining more momentum in tropical countries. The thermal adaptation and thermal comfort index play a significant role in evaluating the outdoor thermal comfort. In this study, the aim is to capture the thermal sensation of respondents at outdoor environment through questionnaire survey and to determine the discomfort index (DI) to measure the thermal discomfort level. The results indicated that most respondents had thermally accepted the existing environment conditions although they felt slightly warm and hot. A strong correlation between thermal sensation and measured DI was also identified. As a result, a new discomfort index range had been proposed in association with local climate and thermal sensation of occupants to evaluate thermal comfort. The results had proved that the respondents can adapt to a wider range of thermal conditions.Validation of the questionnaire data at Putrajaya was done to prove that the thermal sensation in both Putrajaya and UTM was almost similar since they are located in the same tropical climate region. Hence, a quantitative field study on building layouts was done to facilitate the outdoor human discomfort level based on newly proposed discomfort index range. The results showed that slightly shaded building layouts of type- A and B exhibited higher temperature and discomfort index. The resultant adaptive thermal comfort theory was incorporated into the field studies as well. Finally, the study also showed that the DI values were highly dependent on ambient temperature and relative humidity but had fewer effects for solar radiation intensity.

Thermal performance of developed coating material as cool pavement material for tropical regions

The amount of solar energy emitted back from conventional asphalt pavement contributes to the phenomenon of urban heat island (UHI), and the current work was focused on studying the thermal behavior of asphalt pavement developed as a coating material from wasted tile. The surface temperature of asphalt surface with and without coating material for ambient temperature and underground soil temperature was studied. Results showed that the application of developed coating materials could reduce the surface temperature of asphalt pavement up to 4.4°C. Rainfall also played a significant role as a natural coolant during the experimental run by maintaining the surface temperature continuously for 2 days after the rainfall event, with an average surface temperature of 41.9°C. The underground soil temperature of the coated surface showed reduction in the range of 0.8-1.2°C throughout the day. The coating materials achieved their efficiency in reducing the emitted radiation only during noontime and the results show that the developed coating materials have true potential to serve as cool pavement to combat UHI effects.

Lipid production by microalgae Chlorella pyrenoidosa cultivated in palm oil mill effluent (POME) using hybrid photo bioreactor (HPBR)

Palm oil mill effluent (POME) as high organic wastewater is a promising substrate in the scenario of algae bloom, by enhancing its lipid production to be further used in biofuel manufacturing. In this research, effect of POME as high nutritional substrate, different cultivation scales such as flask or hybrid photo bioreactor (HPBR), carbon-to-total nitrogen (C:TN) ratio, various light and dark cycles, and diverse organic loading rates (OLR) on the lipid productivity of microalgae Chlorella pyrenoidosa was assessed. Results demonstrated high microalgae growth rate (1.80 d �1 ) at 250 mg COD/L of substrate, while moderate increase (1.37 d �1 ) and growth inhibition (0.80 d �1 ) were recorded at 500 mg COD/L and 1,000 mg COD/L of substrate concentration, respectively. Furthermore, a result proved that low-volume cultivation of microalgae in a flask with lipid productivity at 1.78 mg/L d significantly restricted microalgae production compared with larger scale such as HPBR with lipid productivity at 230 mg/L d. Moreover, highest lipid production at 44.5, 114.9, and 100.5 mg/L d, C:TN ratio at 100:6 and OLR at 36 kg COD/m 3 d, respectively, were documented for continuous illuminaion (24 h). The combination of above conditions can be optimal setting to reach the highest lipid productivity by microalgae C. pyrenoidosa. In addition, the results of this study can be further considered in microalgae lipid production using other wastewaters in order to enhance the lipid production as well as wastewater treating functions.

A study on large scale cultivation of Microcystis aeruginosa under open raceway pond at semi-continuous mode for biodiesel production

The study explores on upstream and downstream process in Microcystis aeruginosa for biodiesel production. The alga was isolated from temple tank, acclimatized and successfully mass cultivated in open raceway pond at semi-continuous mode. A two step combined process was designed and harvested 99.3% of biomass, the daily dry biomass productivity was recorded up to 28gm(-2)day(-1). The lipid extraction was optimized and achieved 21.3%; physicochemical properties were characterized and found 11.7% of FFA, iodine value 72% and 99.2% of ester content. The lipid was transesterified by a two step simultaneous process and produced 90.1% of biodiesel; the calorific value of the biodiesel was 38.8MJ/kg. Further, the physicochemical properties of biodiesel was characterized and found to be within the limits of American ASTM D6751. Based on the areal and volumetric biomass productivity estimation, M. aeruginosa can yield 84.1 tons of dry biomass ha(-1)year(-1).

Biofiltration process as an ideal approach to remove pollutants from polluted air

AbstractMost developing and developed countries are facing the problems and challenges of air pollution. Many governments have enacted laws and policies to enforce industrial activities to reduce air contaminating emissions and are mainly carried out by installation of air pollution control systems. Therefore, the use of suitable technique such as biofiltration processes to control air pollutants is necessary. Although many studies have been published on the designing and operations of polluted air treatment using biofiltration processes but a comprehensive review on it is still lacking. Till now due to conceptual designing and operational knowledge, several cases of failure or sub-optimum designing has been reported about the use of biofiltration process to treat polluted air. This paper presents a comprehensive review of biofiltration processes and technology for the control of organic and inorganic pollutants as an ideal approach to remove pollutants from polluted air. It also covers classification, fu...

Efficiency of barium removal from radioactive waste water using the combination of maghemite and titania nanoparticles in PVA and alginate beads

In this paper, both maghemite (γ-Fe2O3) and titanium oxide (TiO2) nanoparticles were synthesized and mixed in various ratios and embedded in PVA and alginate beads. Batch sorption experiments were applied for removal of barium ions from aqueous solution under sunlight using the beads. The process has been investigated as a function of pH, contact time, temperature, initial barium ion concentration and TiO2:γ-Fe2O3 ratios (1:10, 1:60 and 1). The recycling attributes of these beads were also considered. Furthermore, the results revealed that 99% of the Ba(II) was eliminated in 150min at pH 8 under sunlight. Also, the maghemite and titania PVA-alginate beads can be readily isolated from the aqueous solution after the process and reused for at least 7 times without significant losses of their initial properties. The reduction of Ba(II) with maghemite and titania PVA-alginate beads fitted the pseudo first order and second order Langmuir-Hinshelwood (L-H) kinetic model.

Evaluation of gas retention time effects on the bio-trickling filter reactor performance for treating air contaminated with formaldehyde

The effect of different gas retention times (GRTs) on the efficiency of formaldehyde (FA) removal has been studied using a bio-trickling filter reactor (BTFR) for obtaining the optimal operating conditions. Mathematical models to determine the optimum process conditions of the BTFR system for FA removal from contaminated air are developed. Approximately 66% of the FA introduced into the BTFR treatment process dissolved in the nutrient solution, and about 34% of the residual FA was still present in the air. The predominant bacteria on the surface of supporting materials are identified as the five bacterial colonies Salmonella bongori, Salmonella choleraesuis subsp. arizonae, Salmonella typhimurium, Serratia entomophila and Serratia ficaria, and they have the ability to metabolise FA from two-phases (gas and liquid), as a source of carbon and energy. The optimum removal efficiencies of 450 mg FA L−1 of contaminated air ranged from 95 to 99% are verified for GRTs ranging from 100 to 150 s. Exponential models are proposed as a new approach for determining the optimal operating conditions of the BTFR system and can make significant contributions to improving the air quality.

Removal of formaldehyde from polluted air in a biotrickling filter reactor

AbstractOptimization of biotrickling filter reactor (BTFR) for the removal of formaldehyde contained in synthetic contaminated air was investigated. The importance of formaldehyde from contaminated air is necessary mainly because it is toxic, carcinogen, and mutagen for humans. Although several studies have been conducted on formaldehyde removal by using BTFR from contaminated air, but optimum conditions for formaldehyde removal is not being studied using a trustable method. The determination of optimum condition to remove formaldehyde was carried out with Taguchi experimental design method. The influence of different factors (pH, nitrogen, phosphorus, formaldehyde concentration) on formaldehyde removal efficiency in BTFR was determined, and the optimum condition for maximizing this response was obtained. The result shows that pH has a greater effect on BTFR efficiency for formaldehyde removal. By operating BTFR in optimum condition, the removal rate increased up to 98%. Thus, the operation of BTFR at opt...

Removal Rate of Organic Matter Using Natural Cellulose via Adsorption Isotherm and Kinetic Studies.

In this study, the removal of natural organic matter (NOM) using coconut fiber (CF) and palm oil fiber (POF) was investigated. Preliminary analysis was performed using a jar test for the selection of optimal medium before the fabricated column model experiment. The equilibrium studies on isotherms and kinetic models for NOM adsorption were analyzed using linearized correlation coefficient. Results showed that the equilibrium data were fitted to Langmuir isotherm model for both CF and POF. The most suitable adsorption model was the pseudo-first-order kinetic model for POF and pseudo-second-order kinetic model for CF. The adsorption capacities achieved by the CF and POF were 15.67 and 30.8 mg/g respectively. Based on this investigation, it can be concluded that the POF is the most suitable material for the removal of NOM in semi polluted river water.Al Asfar Lake is a shallow wetland and habitat for wildlife and birds in a desert environment. The water of this lake is originated from the drainage water collected by earthen drainage network and discharged into the lake. The purpose of this study was to assess physico- chemical characteristics and some of heavy metals in Al Asfar lake water. The studied parameters are iron, manganese, copper, zinc, cadmium, chromium, lead, pH, electrical conductivity, and nitrate. Forty-five surface water samples were collected in March 2013. The results revealed that the pH ranged from 7.33 to 8.67, electrical conductivity ranged from 8.28 to 11.34 dS/m, and NO(3)(-) ranged from 0.84 to 2.29 mg/L. In addition, heavy metals concentrations in water were found in the following order: Fe > Mn > Cu > Zn > Cd > Cr = Pb. The mean concentrations of heavy metals in surface water of Al Asfar lake ranged from 0.027 to 0.159 ppm, 0.007 to 0.142 ppm, 0.005 to 0.017 ppm, 0.005 to 0.066 ppm, 0.001 to 0.033 ppm, 0 ppm, and 0 ppm for iron, manganese, copper, zinc, cadmium, chromium, and lead, respectively. Moreover, pH, NO(3)(-), Fe, Mn, and Zn concentrations in the surface water of Al Asfar Lake were found to be within the international permissible limits. On the other hand, Cu and Cd concentrations exceeded the international permissible limits. The high level of some parameters of the measured heavy metals could be attributed to the contamination of Al Asfar Lake with discharge water enriched with chemical fertilizers in addition to domestic and industrial effluents.