Anaerobic bioconversion of carbon dioxide to biogas in an upflow anaerobic sludge blanket reactor

The increasing concentration of carbon dioxide (CO2)--the most dominant component of greenhouse gases--in the atmosphere has been of growing concern for many years. Many methods focus on CO2 capture and storage and there is always the risk of CO2 release to the environment. In this study, a new method to convert CO2 to biogas with a high content of methane (CH4) in an anaerobic system with a lab-scale upflow anaerobic sludge blanket reactor at 35 degrees C was developed. In a series of experiments, the reactor was run with and without CO2-saturated solutions including volatile fatty acids (VFAs) as sources of hydrogen. The concentration of dissolved CO2 in the influent solutions was 2.2-6.1 g/L, with corresponding chemical oxygen demand (COD) values of 2.6-8.4 g/L for the solutions. Overall CO2 removal values of 2.7-20 g/day (49-88% conversion) were obtained for the organic loading rates (OLR) and CO2 loading rates of 8-36 gCOD/L day and 6-26 gCO2/L x day, respectively with CH4 purity of above 70%. Also, VFA and COD removal were in the range of 79-95% and 75-90%, respectively. Methanogenic activities of the cultures with the concentrations measured as volatile suspended solids (VSSs) were 0.12-0.40 L CH4/gVSS x d with the highest value for the system containing acetic acid. This anaerobic method can be applied to reduce CO2 emitted to the atmosphere from a wide variety of industrial point sources with a value-added product, CH4.     

Internalisation of externalities: Who bears the cost of pollution control?

Summary The impact of environmental regulations on the welfare of Malaysian palm oil growers, producers, and refiners are evaluated in an open-economy model. The estimated incremental effects of effluent standards and changes have been specifically rather small, with the exception of those upon the growers, but the cumulative effects have been considerable.Dr Khalid Abdul Rahim is a member of staff in the Department of Natural Resource Economics at the Universiti Pertanian Malaysia. This article is based on part of the work undertaken for his PhD dissertation at the University of Illinois, USA.     

Prenatal diagnosis of β-thalassemia in Southern Punjab,Pakistan

Pakistan has a large population of more than 150 million people with an overall carrier frequency of approximately 5.6% for β-thalassemia. Punjab is the largest province of the country having more than 50% of the population. The state of β-thalassemia is alarming as consanguinity is very high (>81%) and the literacy rate is low in South Punjab. A thalassemia prevention program is the need of the hour in this part of Pakistan. In this study, we initiated awareness, screening, and characterization of the mutations causing β-thalassemia as well as a genetic counseling program mainly in the districts of Faisalabad and D.G. Khan to establish prenatal diagnosis, a facility previously unavailable in this region for disease prevention. A total of 248 unrelated transfusion-dependent children and the available members of their families were screened to characterize the mutations and identify the carriers. Genetic counseling was provided to these families and prenatal diagnosis offered. In the samples analyzed, 11 β-thalassemia mutations and three hemoglobin variants were detected mainly by using the Monoplex and Multiplex ARMS-PCR. First-trimester prenatal diagnosis was carried out through chorionic villus sampling (CVS) in seven pregnancies at risk. As a result of our campaign, 145 carrier couples planning to have more children gave their consent to have retrospective prenatal diagnosis in every pregnancy in future. A cooperative trend and a positive attitude toward the prevention of β-thalassemia were noticed in the families with affected children and in the general population. Copyright © 2006 John Wiley & Sons, Ltd.     

Habitat preference and population estimates of Indian pangolin (Manis crassicaudata) in district Chakwal of Potohar Plateau,Pakistan

Indian pangolin (Manis crassicaudata) is a fossorial, “Near threatened” mammalian species occurring in Pakistan and facing a risk of endangerment in its wild habitat. Being nocturnal, ecological data of the species is lacking in the country and in south Asia as well. The current study investigated some ecological parameters of the species like, distribution, habitat analysis, population and food habits in district Chakwal of Potohar Plateau. Illegal trapping and killing by professional nomads for its scales is the main threat to the species in the study area.     

Physical Characterization and Pre-assessment of Recycled High-Density Polyethylene as 3D Printing Material

3D printing has received lots of attention due to its limitless potential and advantages in comparison to traditional manufacturing processes. This study focuses on the most popular type of home 3D printers, namely fused filament fabrication (FFF) printers, which use plastic filaments as the feedstock. The rather high material cost and large amount of plastic waste generated by FFF 3D printers have driven the need for plastic filaments produced from recycled plastic waste. This study evaluates, in terms of physical characterization, the feasibility of using recycled high-density polyethylene (HDPE), one of the most commonly used plastics, as the feedstock for 3D printers, in comparison with the common acrylonitrile butadiene styrene plastic pellets. In-house extrusion using recycled HDPE pellets and flakes is possible. The diameter consistency and extrusion rate results, along with other physical characterization results, including differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared spectroscopy, Raman spectroscopy, and water absorption, suggest that making filaments from recycled HDPE pellets is a viable option, as the obtained filament has favorable water rejection and comparable extrusion rate and thermal stability. Existing methods for overcoming the warping and adhesion problems in 3D printing with HDPE were also reviewed. In order to increase the market competitiveness of waste-derived filaments, optimization of the extrusion process, studies on the mechanical and aging properties, and development of a standard characterization methodology and database are crucial.     

Quantification of polychlorinated biphenyl contamination using human placenta as biomarker from Punjab Province,Pakistan

Environmental Science and Pollution Research - The present study biomonitored the placental polychlorinated biphenyl (PCB) concentrations in women from Punjab Province, Pakistan, that provides the...     

Taurine mitigates nitrite-induced methemoglobin formation and oxidative damage in human erythrocytes

Environmental Science and Pollution Research - Nitrite is present as a noxious contaminant in drinking water and causes oxidative damage in various tissues of humans and animals. It is a well-known...     

A critical review of state-of-the-art electrocoagulation technique applied to COD-rich industrial wastewaters

Environmental Science and Pollution Research - Electrocoagulation (EC) is one of the emerging technologies in groundwater and wastewater treatment as it combines the benefits of coagulation,...