Susmita Lahiri

Selective and sensitive turn-on chemosensor for Al(III) ions applicable in living organisms: nanomolar detection in aqueous medium

A highly sensitive and selective fluorescent reporter L for Al(III) ions was synthesized and characterized by physicochemical and spectroscopic tools along with single crystal X-ray crystallographic study. This is so far the first report of a crystallographically established fluorescence probe having two rhodamine units which make this probe highly sensitive towards Al(III) ions. L, with a high binding affinity towards Al(III) ions of 3.33 × 108 M−2, selectively detects Al(III) ions with almost no interference among various competitive, biologically relevant ions by a strong fluorescence (250 times) as well as colour change in HEPES buffer (1 mM, pH 7.4; acetonitrile/water: 1/3, v/v). The quantum yields (Ф) and molar extinction coefficient (e) of [Al2(L)2(CH3CN)(H2O)(NO3)4](NO3)2 (complex-1) were significantly greater than the sensor L, meaning this probe (L) can detect Al(III) ions at concentrations as low as 3.26 nM, which is comparable with the lowest LOD available in the literature. This non-cytotoxic probe (L) is also an efficient candidate to detect the intercellular distribution of aluminium ions in human lung cancer cells (A549) and Al(III) ions in matured tea leaves.

Aquaponics: A Green and Sustainable Eco-tech for Environmental Cum Economic Benefits Through Integration of Fish and Edible Crop Cultivation

Municipal wastewater generated by household activities is a storehouse of fertilizers often causing eutrophication of aquatic systems and environmental degradation if not properly managed. Aquaponics is a green and sustainable eco-technological approach integrating aquaculture in hydroponic system and can play a pivotal role in harnessing nutrient from wastewater resources. Consequently, the nutrient-rich wastewater may be reclaimed with concurrent production of fish crops and economically important aquatic plants that can fetch high income from wastewater. The present chapter deals with the potentials of aquaponics in turning wastewater into suitable water for producing fish and different crops for food and nutritional security as well as environmental sustainability.

Evaluation of the fertilizer values of stored and fresh human urine in experimental mixed culture of fish and prawn

With a view to closing the nutrient loop between sanitation and fish culture, advanced fry of different species of fish (rohu, bata, mrigal, common carp, tilapia, punti) and larvae of freshwater prawn were reared in twelve experimental tanks in a mixed culture system for 120 days using three treatments (fresh urine, stored urine and mix of fresh and stored human urine) and control in triplicate. The total weight for all the species of fish and prawn in the stored urine (420.0 g) was 18 and 27% higher compared to fresh (356.0 g) and mixed urine (332.0 g) treatments, respectively. Likewise, primary productivity of phytoplankton and heterotrophic bacterial load related to phosphate level of water were also highest and lowest in the stored urine (GPP—508 ± 39.87 mg C m–2 h–1; heterotrophic bacteria—38.38 cfu × 103 mL–1) and control system (GPP—214 ± 38.09 mg C m–2 h–1; heterotrophic bacteria—13.53 cfu × 103 mL–1), respectively. The mean count of E. coli, on the other hand, did not differ between urine fed treatment and control. As a possible mechanism, it is suggested that stored urine upon transfer to aquaculture pond underwent degradation and mineralization that induced the autotrophic and heterotrophic food webs conducive to fish growth.

Current status of arsenic contamination in drinking water and treatment practice in some rural areas of West Bengal, India

The aim of the present investigation was to draw the current scenario of arsenic (As) contamination in drinking water of community tube well and drinking water treated by tube wells installed with different adsorbent media-based treatment plants in districts Nadia, Hooghly and North 24-Parganas districts, West Bengal, India. As removal efficiencies of different treatment plants varied from 23 to 71%, which is largely governed by adsorption capacity of adsorbent and influencing environmental factors. Though investigated treatment plants removed substantial amount of As from tube well water, high As concentration in treated drinking water was retained after passing through the treatment plants. This high level of As concentration in tube well water and retention of high As concentration in treated drinking water were severe for the consumers which therefore, indicating the improvement of removal efficiency of treatment plant by meticulously considering favorable influencing factors or/and application of other high capacity treatment alternatives to adsorb the excess As retained in drinking water and regular monitoring of As concentration in the treated drinking water are indispensable.

Biogeochemical Cycling Bacteria and Nutrient Dynamics in Waste Stabilization Pond System

Wastewater generated from different sources creates environmental problems after entering the aquatic ecosystem due to its heavy organic load and other undesirable toxicants. As a consequence, biological and chemical oxygen demand increases with depletion of oxygen level of water; all the biotic organisms suffer from stress-related symptoms often reaching to lethal limits. However, wastewater may become a useful resource for various economic-driven activities. Wastewater reuse is primarily dependent on the microbial degradation of different nutrients present in sewage. Thus, biogeochemical cycling bacteria have profound role on the decomposition, degradation and regeneration of nutrients from organic sewage water. Thus, the metabolism and turnover of the whole sewage-fed ponds are regulated by nutrient cycling and energy flow in the trophic level. Waste stabilization pond has been recognized as effective treatment system with removal of as high as 90–95% dissolved organic matter and reducing pathogens through microbial activities under aerobic and anaerobic conditions in trickling filter, activated sludge processes, etc. Interactions within and between carbon, nitrogen and phosphorus pools in nutrient cycles of wastewater-fed ponds ultimately result in nutrient removal from wastewater. A series of waste stabilization ponds (anaerobic, facultative and maturation) in which the detritus food chain is dominant over the grazing food chain is popular. It is evident that microbial activities play a crucial role in nutrient recovery from wastewater through microbial degradation of organic load leading to increased biological production while accelerating the enhancement of water quality through microbial-driven ecological processes.

Understanding the Soil-Water Interactions for Sustainable Ecosystem Services in Aquatic Environments

Healthy soils are of the utmost importance to society for the variety of ecosystem services they provide in both terrestrial and aquatic systems. Within aquatic systems, soils play an active role in carbon cycling and interactions between soils and water, and additional components of aquatic ecosystems can control the balance of carbon, whether the system becomes a net carbon source or sink. Understanding the interactions between soils and overlying water is crucial to developing adaptive strategies to mitigate climate change. An enhanced, holistic understanding of primary ecosystem drivers in mixed aquatic and soil systems is paramount for guiding their future construction and management to maximize their beneficial use while minimizing negative environmental impacts. Aeration and water circulation devices can be used to improve dissolved oxygen content of the wastewater pond system. Raking may be practiced to improve the ecological conditions of pond soils for encouraging healthy conditions and animal associations of the pond bottom particularly in wastewater-fed systems. The present chapter provides a review of different aspects of soil-water interactions and strategies to maintain ecosystem health for sustainable development.

Arsenic Removal from Groundwater by Solar Driven Inline-Electrolytic Induced Co-Precipitation and Filtration—A Long Term Field Test Conducted in West Bengal

Arsenic contamination in drinking water resources is of major concern in the Ganga delta plains of West Bengal in India and Bangladesh. Here, several laboratory and field studies on arsenic removal from drinking water resources were conducted in the past and the application of strong-oxidant-induced co-precipitation of arsenic on iron hydroxides is still considered as the most promising mechanism. This paper suggests an autonomous, solar driven arsenic removal setting and presents the findings of a long term field test conducted in West Bengal. The system applies an inline-electrolytic cell for in situ chlorine production using the natural chloride content of the water and by that substituting the external dosing of strong oxidants. Co-precipitation of As(V) occurs on freshly formed iron hydroxide, which is removed by Manganese Greensand Plus® filtration. The test was conducted for ten months under changing source water conditions considering arsenic (187 ± 45 µg/L), iron (5.5 ± 0.8 mg/L), manganese (1.5 ± 0.4 mg/L), phosphate (2.4 ± 1.3 mg/L) and ammonium (1.4 ± 0.5 mg/L) concentrations. Depending on the system setting removal rates of 94% for arsenic (10 ± 4 µg/L), >99% for iron (0.03 ± 0.03 mg/L), 96% for manganese (0.06 ± 0.05 mg/L), 72% for phosphate (0.7 ± 0.3 mg/L) and 84% for ammonium (0.18 ± 0.12 mg/L) were achieved—without the addition of any chemicals/adsorbents. Loading densities of arsenic on iron hydroxides averaged to 31 µgAs/mgFe. As the test was performed under field conditions and the here proposed removal mechanisms work fully autonomously, it poses a technically feasible treatment alternative, especially for rural areas.