Oxidative co-treatment using hydrogen peroxide with anaerobic digestion of excess municipal sludge.

The effect of an oxidative co-treatment on anaerobic digestion of a mixture of primary and waste activated sludge was investigated. The oxidant used in this study was hydrogen peroxide (H2O2). A maximum improvement in solid destruction of 15.2% was achieved in the overall process, with a dosage of 2.0 g H2O2/g influent volatile suspended solids (VSS(influent)). All configurations operated at this dosage also showed statistically significant increases in solids removal. A statistically significant enhancement in overall solids destruction was observed for the lower oxidant dosage (0.5 H2O2/g VSS(influent)). Surprisingly, for 1.0 g H2O2/g VSS(influent), only one of the three configurations involving oxidative co-treatment showed significant increases in solids destruction. Special attention was paid to the performance of this process relative to fecal coliforms destruction. Class A biosolids were obtained for all the different hydrogen peroxide dosages used when oxidative co-treatment is combined with a two-stage anaerobic digestion process.     

Nature of distribution of mercury in the sediments of the river Yamuna (tributary of the Ganges), India

Suspended Particulate Matter (SPM), surface (bed sediments) and short length cores of sediments collected from the largest tributary of the river Ganges, namely the river Yamuna, were analysed for total mercury as well as its fractionation in various size and chemical sites in the sediments following standard procedures. Also, attempts were made to determine the vertical distribution in sediments in relation to the recent timescale of a few decades. Our observations indicate that the SPM in general showed higher levels of total mercury compared to the surface sediments while at places the enhancement could be by a factor of 10, say around 25 microg g(-1) in the downstream region that integrates the industrial midstream and agricultural downstream terrain near its confluence with the Ganges. Surface sediments in the upstream direction near the Himalayan foothills and SPM in the lower reaches showed significant high Index of Geoaccumulation (Igeo) as defined by Müller. Size fractionation studies indicate that the finer fraction preferentially showed higher levels of mercury while in the lower reaches of the river, the total mercury is equitably distributed among all size fractions. The proportion of the residual fraction of mercury in relation to mobile fractions, in general decreases downstream towards its confluence with the Ganges river. In sediment cores, the vertical distribution show systematic peaks of mercury indicating that addition of this toxic metal to the aquatic system is in direct proportion to the increase in various types of human activities such as thermal power plants, land use changes (urbanisation) in the midstream region and intensive fertiliser application in lower reaches of this vast river basin.     

Factors affecting arsenic concentration in groundwater in West Bengal

Groundwater is the major source of drinking water for the population in Malda district, West Bengal. Holocene sediments from Himalayas have contaminated those places through the river Ganges and arsenic was found a potential groundwater contaminant. Field and laboratory experiments were attempted to identify the relationship between arsenic versus Eh of groundwater and content specific elements (As, Co, Mn, Fe, C and S) in different types of Holocene sediments on a freshly constructed wells. Arsenic versus Eh of groundwater and Holocene clay over Holocene sand were found performing a major role in the aquifers of arsenic affected areas.     

Fluoride in fractionated soil samples of Ajmer district,Rajasthan

The natural abundance of fluoride in soils of the Ajmer distict, Rajasthan was examined. From undisturbed soil, the top 15 cm of the profile was examined and the soil split into fractions based on sand, silt and clay particle size. Clay contained a high amount of fluoride, whereas sand and silts are enriched with much less fluoride. The relation between the soil fractions in observed clay fraction fluoride content matched groundwater fluoride variation. However, the enrichment of fluoride material extracted from the largest soil fraction had considerably lower amounts of clay relative to that from the smaller fractions.     

Neem extract–blended nanocellulose derived from jackfruit peel for antibacterial packagings

Environmental Science and Pollution Research - The use of jackfruit peel as a source for natural and fully biodegradable “nanocellulose” (NC) for the production of bioplastics with...