Autotrophic Biological Denitrification for Complete Removal of Nitrogen from Septic System Wastewater

The overall objective of this research was to develop a reliable, robust, and maintenance-free passive system for biological denitrification in on-site wastewater treatment systems. The process relies on sulfur oxidizing denitrifying bacteria in upflow packed bioreactors. Since this process consumes alkalinity, it is necessary to add a solid-phase buffer that can scavenge the H⁺ as it is generated by the biologically-mediated reaction and arrest the drop in the pH value. This study investigated the use of limestone, marble chips and crushed oyster shell as solid-phase buffers that provide alkalinity. Two bench-scale upflow column reactors and two field-scale bioreactors were constructed and packed with sulfur pellets and an alkalinity source. The pilot scale bioreactors (∼200 L each) were installed at the Massachusetts Alternative Septic System Test Center (MASSTC) in Sandwich, MA. The pilot-scale bioreactors performed better when oyster shell was used as the solid-phase buffer vis-à-vis marble chips. In both (pilot-scale and laboratory-scale) systems, denitrification rates were high with the effluent NO₃ ⁻ —N concentration consistently below 8 mg/L.     

Interparticle diffusion and thermodynamic modeling studies for the removal of heavy metals using mixed adsorbents in industrial effluents

Pollution of water, air, and soil by industrial effluents is a major problem nowadays. A variety of contaminants are too responsible for changing the physicochemical properties of the receiving body. There are practical treatment solutions available to clean up contaminants from various resources. The term “adsorption” refers to one of them. The purpose of the research work is to remove heavy metals from industrial effluent. Mixed adsorbents prepared from activated charcoal and bone charcoals were used to remove the copper and cadmium ions. The experiment carried out in a batch operation and modeling of these data for intraparticle diffusion and thermodynamic calculations were reported in this research work. At optimum operating condition pH 6; metal ion concentration 50 mg/L; dose 5 g/L; agitation 180 rpm and temperature 40°C maximum 99.41% copper ions and 88.12% cadmium ion removal was achieved. Cadmium ions were well fitted in the thermodynamic model compared to copper ions, as demonstrated by the higher correlation coefficient R² (0.9824) value. Intra particle diffusion demonstrated that film diffusion was a rate-limiting step at the start of the reaction, while microporous intraparticle diffusion was the rate-determining phase later on. A Fourier transformation infrared spectroscopy, X-ray diffraction, and scanning electron micrography analysis confirmed the suitability of mixed adsorbents for the removal of cadmium and copper metal ions.     

Study of Geochemical Association of Some Trace Metals in the Sediments of Chilika Lake: A Multivariate Statistical Approach

In order to establish the natural processes and geochemical factors responsible for enrichment of trace metal ions (Cu, Co, Ni, Zn and Cr) with respect to textural parameters (sand, silt and clay weight percentages) along with depth, multivariate statistical approach has been carried out for sediments in different water zones of Chilika lake, the largest brackish water lagoon in Asia. The rotated varimax factor results reveal that Cobalt enrichment is controlled by both textural parameters as well as adsorption mechanism. In fresh and saline water region, textural parameters and in mixed water, adsorption phenomenon predominates. Zn in fresh water is related to clay, whereas it is in adsorbed state in mixed water. Cu in fresh water sediments is in absorbed state and in mixed water it is related to depth and Co concentration. Cr does not show any specific association in fresh water, but in both mixed and saline water it is associated with clay minerals. Although both textural parameters and adsorption mechanism play an important role for the enrichment of trace metal ions in these lagoonal sediments, their relative importance varies with specific metal ions as well as the water quality. Sequential extraction technique was used to characterize the various forms of metals in the < 63μ size sediments of Chilika lake. The concentrations determined indicated selective accumulation of the various metals in the different phases with spatial variability in different water zones. Slightly higher availability of Co and Zn near Balugaon township in exchangeable phase may be related to anthropogenic activities. Among the non-lithogenous (NL) phases, reducible phase associated with higher concentration of Ni, Cu and Cr. Organic bound Zn and Co contributed highest percentages among NL fractions. Residual fraction contributed more than 50% in most of the cases, reflected the predominance of physical weathering, high erosion rate along the drainage basin.     

Light non-methane hydrocarbons at two sites in the Indo-Gangetic Plain

Measurements of light (C(2)-C(5)) non-methane hydrocarbons (NMHCs) were made along with ozone (O(3)), oxides of nitrogen (NO(x)), carbon monoxide (CO) and methane (CH(4)) at Hissar and Kanpur in the Indo-Gangetic Plain (IGP) in India during the month of December, 2004. Air samplings during noon and evening hours provided an opportunity to study the emission characteristics and changes during this period at these sites. The mixing ratio of O(3) was higher during noon hours due to photochemical formation, while the levels of precursor gases showed elevated values during the evening hours on a clear sky day. On foggy days there is no such variation. The lower mixing ratios of O(3) observed on foggy days could be due to the slower rate of photochemical formation caused by a reduction in solar flux and surface deposition caused by the presence of a stable planetary boundary layer. Propene and ethene show the highest evening to noon ratio due to their faster reactivities with OH radicals. Correlations among different species of the measured gases indicate contributions of emissions from biomass and biofuel burning as well as fossil fuel combustion. Although qualitatively in relation to O(3), the propylene (propene) equivalents of NMHCs have been calculated to investigate their roles in O(3) photochemistry and compared with the data from Ahmedabad, an urban site in western India. The important result, which has emerged from the analysis of the observed data, is that while the total amount of these NMHCs is least at Hissar and highest at Ahmedabad, the total propylene-equivalent is highest at Hissar and lowest at Ahmedabad. Further, these two sites in the IGP show significant contributions, almost 72-77%, by propene and ethene while the contribution by these two gases at Ahmedabad is only about 47%. The surface level mixing ratios of O(3) could be treated as representative for the chemical characterization of air mass at a regional scale over the IGP as the month long trends of O(3) show significant similarity compared to the trends in precursors at the two sites.     

Nutrient dynamics and seasonal variation of phytoplankton assemblages in the coastal waters of southwest Bay of Bengal

In order to understand the phytoplankton community structure and its relationship with the environmental variables in the near shore waters of Kalpakkam, east coast of India, observations were carried out during 2008–2009. Phytoplankton population was comprised of 219 species, and the density was higher during the southwest monsoon (SWM) and inter-monsoon seasons than that of north east monsoon (NEM) season. The nutrient status on a temporal and spatial scale indicated the impact of point sources carrying anthropogenic runoff. Comparison of ambient nutrient ratios with the Redfield ratio (N/P/Si?=?16:1:16) showed a clear temporal variation in the factors that regulate the phytoplankton growth. SWM and inter-monsoon season was evident to have an acute N-limitation of algal growth (~76 %) whereas P-limitation was encountered during the NEM season (~75 %). Interestingly, a sizable population of cyanobacteria (Trichodesmium erythraeum) were noticed during NEM season when there was an exponential increase in nitrogen concentration, probably due to nitrogen fixation. No significant impact of temperature on phytoplankton proliferation was observed in situ during the study period.     

Spatiotemporal evaluation of water quality incidents in Japan between 1996 and 2007

We present a spatiotemporal evaluation of water quality incidents in Japan considering incident numbers, incident causes, pollutant categories, and pollution effects. Water pollution incidents in first-class river systems almost tripled to about 1487 in the 12 years from 1996 to 2007. In addition, oil makes up the largest proportion of pollutants nationwide (76.61%) and the major source of pollution for each region in Japan. Moreover, every category shows a growth trend, especially since 2005. The main cause of incidents was “Unknown” (43%), followed by “Poor working practice” (24%), and then by “Accident” (10%) and “Other” (10%). In Hokuriku, however, the main cause of incidents was “Poor working practice” (36%), which is greater than “Unknown” (30%). Finally, waterworks (approximately 60%) was the largest of four kinds of water supply infrastructure affected by pollution incidents, followed by simplified waterworks. The population affected by offensive odors and tastes peaked in 1990 and has been decreasing. Overall, the results show the characteristics of incidents from 1996 to 2007, with significant implications for adaptation measures, strategies and policies to reduce water quality incidents.     

Exchange of polycyclic aromatic hydrocarbons across the air-water interface at the creek adjoining Mumbai harbour, India

Concentration levels of polycyclic aromatic hydrocarbons (PAHs) have been determined in air and water in order to estimate the magnitude and direction of gas flux across the air-water interface at the creek adjoining the Mumbai harbour, India. The range of total PAHs was found to be 4.1-30.4 ng/m3 in air and 84.3-377.5 ng/l in seawater, respectively. The lower molecular weight PAHs revealed positive values of the fluxes indicating the tendency for transfer of these contaminants from water to air. In contrast, fluxes of less volatile compounds like benzo(k)fluoranthene and benzo(a)pyrene were always from the atmosphere into the surface water of the creek at all locations and sampling periods. While the fugacity ratio ranged from 0.12 to 6.97, it was found greater than 1 for the lower molecular weight PAHs and less than 1 for higher molecular weight PAHs. The present study suggests the active transfer of lower molecular weight dissolved PAHs into the atmosphere due to volatilization and deposition of higher molecular weight gas-phase PAHs into the surface water.     

Identification of hot spots and well managed areas of Pichavaram mangrove using Landsat TM and Resourcesat—1 LISS IV: an example of coastal resource conservation along Tamil Nadu Coast, India

The present work is a multi-temporal satellite based study on the spatial dynamic of an important coastal habitat, the Pichavaram mangrove ecosystem, over a period of 15 years. The Pichavaram mangrove forest near Chidambaram, South India is the second largest mangrove forest in the world. Unsupervised classification, the Iterative Self Organising Data Analysis Technique (ISODATA), has been used to classify the mangrove cover into the open and dense classes. The status of the classes has been monitored using Landsat TM of 1991, 2001, and Resourcesat–1 LISS IV of 2006 satellite data. The study demonstrated that by classifying mangrove ecosystem into just the 3 classes using remote sensing data and by studying their temporal variations, it is possible to get a reasonably accurate picture of the extent and condition of the mangrove ecosystem. The total area of the Pichavaram mangrove showed a net increase of 2.51 km² within a span of 15 years (1991 to 2006). The hot spots that are at a risk of being degraded, and on the other hand, the mangrove areas that are well managed are identified using Geographical Information System (GIS) tools for the restoration and conservation measures.     

Accurate prediction of air quality response to emissions for effective control policy design

Designing effective control policy requires accurate quantification of the relationship between the ambient concentrations of O₃and PM_2.5and the emissions of their precursors.However,the challenge is that precursor reduction does not necessarily lead to decreases in the concentrations of O₃and PM_2.5,which are formed by multiple precursors under complex physical and chemical processes;this calls for the development of advanced model technologies to prov...