Acute and chronic toxicity of nickel to nitrifiers at different temperatures

This study investigated the acute nickel toxicity on nitrification of low ammonia synthetic wastewater at 10, 23, and 35°C. The nickel inhibition half-velocity constants(K_(I,Ni)) for ammonia oxidizing bacteria(AOB) and nitrite oxidizing bacteria(NOB) based on Ni/MLSS ratio at 10, 23, and 35°C were 5.4 and 5.6 mg Ni/g MLSS, 4.6 and 3.5 mg Ni/g MLSS, and 9.1 and 2.7 mg Ni/g MLSS, respectively. In addition, chronic toxicity of nickel to nitrification of low ammonia synthetic wastewater was investigated at 10°C in two sequencing batch reactors(SBRs). Long-term SBRs operation and short-term batch tests were comparable with respect to the extent of inhibition and corresponding Ni/MLSS ratio. The μ_(max), b, and K_o of AOB were 0.16 day~(-1), 0.098 day~(-1) and 2.08 mg O_2/L after long-term acclimatization to nickel of 1 mg/L at 10°C, high dissolved oxygen(DO)(7 mg/L) and long solids retention time(SRT) of 63–70 days. Acute nickel toxicity of nitrifying bacteria was completely reversible.     

Environmental impacts of the widespread use of chlorine-based disinfectants during the COVID-19 pandemic

Environmental Science and Pollution Research - Chlorinated disinfectants are widely used in hospitals, COVID-19 quarantine facilities, households, institutes, and public areas to combat the spread...     

The idea of sustainable development

In this lecture, I demonstrate how very different macroeconomic history begins to look if Nature is included as a capital asset in production activities. The tentative conclusions I draw from the evidence are: (1) high population growth in the world’s poorest regions (South Asia and sub-Saharan Africa) has been an obstacle to the achievement of sustainable economic development there; relatedly, (2) when population growth is taken into account, the accumulation of manufactured capital, knowledge, and human capital (health and education) has not compensated for the degradation of natural capital in South Asia and sub-Saharan Africa and, in all probability, even in the UK and the US; (3) China is possibly an exception to (1) and (2). This article is based on the Keynote Lecture delivered at the international symposium on “Sustainability in an Unequal World”, held in Tokyo on November 24, 2006. The exposition relies on my book, Economics: A Very Short Introduction, Oxford University Press, Oxford, 2007. The author is the Frank Ramsey Professor of Economics at the University of Cambridge and a Fellow of St. John’s College, Cambridge.     

Fairness between generations and the social rate of discount

This paper analyses the relationship between social rates of discount to be used in benefit-cost analysis of investment projects and optimal intertemporal plans of capital accumulation and resource depletion. The discussion is conducted in the context of models that incorporate exhaustible natural resources. It is argued that discount rates are a derived concept and that they ought to be arrived at from a consideration of our sense of intergenerational justice and optimal programmes arrived at from intergenerational welfare criteria.     

Effect of Pretreatment with UV Radiation on Physical and Mechanical Properties of Photocured Jute Yarn with 1,6-Hexanediol Diacrylate (HDDA)

Jute yarns were grafted with a single impregnating monomer 1,6-hexanediol diacrylate (HDDA) in order to improve the physicomechanical properties. Jute yarns soaked for different soaking times (3, 5, 10, and 30 minutes) in HDDA+MeOH solutions at different proportions (1–10% HDDA in MeOH [v/v] along with photoinitiator Darocur-1664 [3%]) were cured under UV lamp at different UV radiation intensities (two, four, six, and eight passes). Concentration of monomer, soaking time, and intensity of UV radiation were optimized with extent of mechanical properties such as tensile strength, elongation at break, and modulus. Enhanced tensile strength (67%), modulus (108%), and polymer loading (11%) were achieved with 5% HDDA concentration, 5-minute soaking time, fourth pass of UV radiation. To further improve the mechanical properties, the jute yarns were pretreated with UV radiation (5, 10, 15, 30, and 50 passes) and treated with optimized monomer concentration (5%). UV-pretreated samples showed the enhanced properties. The tensile strength and modulus increase up to 84% and 132%, respectively, than that of virgin jute yarn. An experiment involving water absorption capacity shows that water uptake by treated samples was much lower than that of the untreated samples. During the weathering test, treated yarns exhibited less loss of mechanical properties than untreated yarns.     

Residual fate and persistence of endosulfan (50 WDG) in Bengal gram (Cicer arietinum)

A detailed study has been presented on heavy metal content of the Iture Estuary. Waters of the Sorowie and Kakum rivers that supply water into the Estuary were investigated to ascertain heavy metal pollution levels due to anthropogenic activities. Concentration s of Cd, Zn, Se and Pb were measured. The study shows pre-occupying pollution levels that constitute a threat to both terrestrial and aquatic ecosystems. The abundance of metals in the Estuary is in the order Zn > Pb > Cd > Se. The level of Cd in the Iture Estuary ranged between 0.011 mg/l and 0.041 mg/l while Se was in the range 0.018 mg/l to 0.029 mg/l, Pb 0.020 mg/l to 0.075 mg/l and Zn 0.040 to 2.45 mg/l. The impact of contaminated water from the Sorowie River on the Iture Estuary was outstanding and the study points out the importance of the Sorowie River as a primary pollution source to the Iture Estuary. The pollution of the Iture Estuary was found to be connected to human activities in its catchments.     

Statistical approaches for hydrogeochemical characterization of groundwater in West Delhi, India

Parametric statistical approaches, correlations and multiple linear regressions were used to develop models for the interpretation of hydrogeochemical parameters in the Western part of Delhi state, India. The hydrogeochemical parameters indicated that the groundwater quality is not safe for consumption. The water is moderately saline and the salinity level is increasing over time. There is also the problem of nitrate pollution. The correlation between electrical conductivity (EC) and other water quality parameters except potassium (K(+)), nitrate (NO(3)(-)) and bicarbonate (HCO(3)(-)) is significantly positive and Ca(++)+ Mg(++)/Na(+)+ K(+) is significantly negative. In predicting EC, the multiple R(2) values of 0.996 and 0.985 indicate that 99.6% and 98.5% variability in the observed EC could be ascribed to the combined effect of Na(+), HCO(3)(-), Cl(-), SO(4)(--), NO(3)(-) and Ca(++)+ Mg(++) for the year of 2005 and 2006 respectively. Out of 99.6% of the variability in EC in 2005, 51.2% was due to Cl(-) alone, and 8.5%, 12.5%, 6.1%, 14.7% and 6.7% were due to Na(+), HCO(3)(-), SO(4)(--), NO(3)(-) and Ca(++) + Mg(++). Similarly in 2006, out of 98.5% of the variability in EC, 48.5% was due to Cl(-) alone, and 10.4%, 12.7%, 5.3%, 17.2% and 4.4% were due to Na(+), HCO(3)(-), SO(4)(--), NO(3)(-) and Ca(++)+ Mg(++). The analysis shows that a good correlation exists between EC, Cl(-) and SO(4)(--) either individually or in combination with other ions and the multiple regression models can predict EC at 5% level of significance.     

Petroleum waste biodegradation with porous biomass support system (PBSS) on rotating biological contactor

A laboratory scale study was conducted to assess the feasibility of the new coupling of rotating biological contactor (RBC) plus porous biomass support system (PBSS) using polyurethane foam as porous support media to biodegrade petroleum refinery wastewater. Polyurethane foam was attached on disks of two four-stage laboratory scale cascade connected RBC units.The two RBC units were operated simultaneously at different but constant, flowrates giving hydraulic loading rates of 0.01, 0.02, 0.03, 0.04 m3/m2/d in two runs keeping the same rotational speed 10 r/min throughout. Organic loading was a less controllable factor in this study.For all of the hydraulic loadings, it was found that the removal efficiency of total chemical oxygen demand (TCOD) and oil were above 80 percent. Ammonia nitrogen and phenol removal were above 90 and 80 percent respectively. The maximum biomass concentration within polyurethane foam was about 30 g/m2 in the first stage for 0.03 m3/m2/d hydraulic loading.The results show that t