A.K. Upadhyay

Constructed wetland as an ecotechnological tool for pollution treatment for conservation of Ganga river

With aim to develop an efficient and ecofriendly approach for on-site treatment of sewage, a sub-surface flow constructed wetland (CW) has been developed by raising potential aquatic macrophytes; Typha latifolia, Phragmites australis, Colocasia esculenta, Polygonum hydropiper, Alternanthera sessilis and Pistia stratoites in gravel as medium. Sewage treatment potential of CW was evaluated by varying retention time at three different stages of plant growth and stabilization. After 6 months, monitoring of fully established CW indicated reduction of 90%, 65%, 78%, 84%, 76% and 86% of BOD, TSS, TDS, NO3-N, PO4-P and NH4-N, respectively in comparison to inlet after 36 h of retention time. Sewage treatment through CW also resulted in reduction of heavy metal contents. Thus, CW proved an effective method for treatment of wastewater and may be developed along river Ganga stretch as an alternative technology. Treated water may be drained into river to check further deterioration of Ganga water quality.

Chromate tolerance and accumulation in Chlorella vulgaris L.: Role of antioxidant enzymes and biochemical changes in detoxification of metals

A concentration-dependent increase in activity of antioxidant enzymes (catalase, ascorbate peroxidase, glutathione, superoxide dismutase) and carotenoid, MDA level have been observed in the green alga Chlorella vulgaris following chromium exposure at different concentrations (0.01-100 μg ml(-1)). Simultaneously, decrease in growth rate, chlorophyll and protein contents was observed. In case of ascorbate peroxidase, glutathione peroxidase and superoxide dismutase a bell shaped dose response was evident, however, lipid peroxidation followed a linear relationship along with catalase activity, which could be used as biomarker of Cr toxicity and played important role in providing tolerance and subsequently, high accumulation potential of chromium in C. vulgaris. In present investigation, the green alga C. vulgaris respond better under chromium stress in terms of tolerance, growth and metal accumulating potential at higher concentration of Cr (VI) which could be employed in decontamination of chromium for environmental cleanup.

Amelioration of arsenic toxicity in rice: Comparative effect of inoculation of Chlorella vulgaris and Nannochloropsis sp. on growth, biochemical changes and arsenic uptake.

The present study was conducted to assess the responses of rice (Oryza sativa L. var. Triguna) by inoculating alga; Chlorella vulgaris and Nannochlropsis sp. supplemented with As(III) (50µM) under hydroponics condition. Results showed that reduced growth variables and protein content in rice plant caused by As toxicity were restored in the algae inoculated plants after 7d of treatment. The rice plant inoculated with Nannochloropsis sp. exhibited a better response in terms of increased root, shoot length and biomass than C. vulgaris under As(III) treatment. A significant reduction in cellular toxicity (thiobarbituric acid reactive substances) and antioxidant enzyme (SOD, APX and GR) activities were observed in algae inoculated rice plant under As(III) treatment in comparison to uninoculated rice. In addition, rice treated with As(III), accumulated 35.05mgkg(-1)dw arsenic in the root and 29.96mgkg(-1)dw in the shoot. However, lower accumulation was observed in As(III) treated rice inoculated with C. vulgaris (24.09mg kg(-1)dw) and Nannochloropsis sp. (20.66mgkg(-1)dw) in the roots, while in shoot, it was 20.10mgkg(-1)dw and 11.67mgkg(-1)dw, respectively. Results demonstrated that application of these algal inoculum ameliorates toxicity and improved tolerance in rice through reduced As uptake and modulating antioxidant enzymes. Thus, application of algae could provide a low-cost and eco-friendly mitigation approach to reduce accumulation of arsenic in edible part of rice as well as higher yield in the As contaminated agricultural field.

Arsenic and other heavy metal accumulation in plants and algae growing naturally in contaminated area of West Bengal, India.

The present study was conducted to quantify the arsenic (As) and other heavy metal concentrations in the plants and algae growing naturally in As contaminated blocks of North-24-Pargana and Nandia district, West Bengal, India to assess their bioaccumulation potential. The plant species included five macrophytes and five algae were collected from the nine selected sites for estimation of As and other heavy metals accumulated therein by using Inductively Coupled Plasma Mass Spectrophotometer (ICP-MS). Results revealed that maximum As concentration (117mgkg(-1)) was recorded in the agricultural soil at the Barasat followed by Beliaghat (111mgkg(-1)) sites of North-24-Pargana. Similarly, concentration of selenium (Si, 249mgkg(-1)), lead (Pb, 79.4mgkg(-1)), chromium (Cr, 138mgkg(-1)) was also found maximum in the soil at Barasat and cadmium (Cd, 163mgkg(-1)) nickel (Ni, 36.5mgkg(-1)) at Vijaynagar site. Among the macrophytes, Eichhornia crassipes found more dominating species in As contaminated area and accumulate As (597mgkg(-1)) in the shoot at kanchrapara site. The Lemna minor found to accumulate maximum As (735mgkg(-1)) in the leaves at Sonadanga and Pistia stratiotes accumulated minimum As (24.5mgkg(-1)) in the fronds from Ranaghat site. In case of diatoms, maximum As (760mgkg(-1)) was accumulated at Kanchrapara site followed by Hydrodictiyon reticulatum (403mgkg(-1)) at the Ranaghat site. High concentration of As and other heavy metal in soil indicates long term effects of irrigation with contaminated ground water, however, high concentration of heavy metals in naturally growing plants and algae revealed their mobilization through leaching and possible food chain contamination. Therefore, efficient heavy metal accumulator macrophytes Eichhornia crassipes, Lemna minor, Spirodela polyrhiza may be exploited in removing metals from contaminated water by developing a plant based treatment system. However, As accumulator algal species may be used as a bioresource for understanding algae mediated As detoxification and bioindication studies.

Augmentation of arsenic enhances lipid yield and defense responses in alga Nannochloropsis sp.

The present study was conducted with microalga Nannochloropsis sp. to evaluate its tolerance responses and biofuel perspectives under different arsenic regime (0-1000μM As(III)). Results showed that optimal biomass (61.00±3.72mg/L/d) and lipid productivity (20.27mg/L/d) were obtained in culture treated with 100μM As(III) in comparison to other treatments. In addition, fatty acid profile of alga was in accordance with European biodiesel standards (EN 14214), which reflects good oxidative stability of oil. High antioxidants viz., ascorbic acid, GSH and cysteine tolerance responses as well as lipid yield at 100μM As(III), opens a new insight in the field of algal biology. Thus, microalgae Nannochloropsis sp. may be employ in remediation as well as biodiesel production.

Algal Technologies for Wastewater Treatment and Biofuels Production: An Integrated Approach for Environmental Management

The algae play very important role in mobilizing elements in the aquatic environments and received more attention in recent years as they have ability to absorb and detoxify heavy metals (Ye et al. 2012). Synthesis of phytochelatins and metallothioneins by algae helps in forming complexes with heavy metals and their detoxification (Suresh and Ravishankar 2004). Heavy metal uptake and accumulation in algae from wastewater depend on adsorption process and uptake metabolism (Lomax et al. 2011). For removing organic and inorganic contaminants, nutrients, and metals from wastewater different microalgae have been used (Hirooka et al. 2005; Fierro et al. 2008; Jacome-Pilco et al. 2009). Wastewater treatment by algae is more feasible due to their low cost and high efficiency as they remove contaminants by uptake and accumulation. Algae are capable of biotransforming and mineralizing nutrients and metals growth and development (Semple et al. 1999). Therefore, an integrated algal system can be utilized for wastewater treatment to remove organic matter, nutrients (N&P) from industrial effluents, sewage, and other wastes (Sivakumara et al. 2012).

Designing and construction of simulated constructed wetland for treatment of sewage containing metals

ABSTRACT A simulated horizontal flow constructed wetland (CW) has been designed with gravel medium and aquatic plants Typha latifolia and Polygonum hydropiper to assess its performance efficiency for sewage treatment. Monitoring of fully developed CW revealed a high removal of nutrients and metals from sewage after treatment at varying retention times. The percent (%) removal of biological oxygen demand, total dissolved solids, total suspended solids, PO4-P and total nitrogen in CW planted with T. latifolia were 88.20, 61.9, 72.12, 74.23 and 66.78%; however, with P. hydropiper, reductions were 79.47, 53.47, 55.46, 60.40 and 52.87%, respectively, at 8 d retention time. In addition, T. latifolia and P. hydropiper accumulated substantial amount of metals in their tissues particularly in roots. T. latifolia root accumulated maximum amount of Zn (40.44 µg/g dw) followed by Cu (39.24 µg/g dw), Pb (37.78 µg/g dw) and Cr (19.95 µg/g dw) as compared to P. hydropiper, which was 17.85, 33.43, 36.19 and 9.67 µg/g dw, respectively. Further, plant-specific high translocation factor (>1) of metals were observed at different retention times. Results suggest that simulated CW may be applied as an ecofriendly and low-cost tool to treat sewage before discharge into a fresh water body.

Constructed Wetland: An Ecotechnology for Wastewater Treatment and Conservation of Ganga Water Quality

The rapid growth of water consumption within the urban area due to industrial development, an increase of the urban population, and an improvement of sanitary conditions is accompanied by the equally rapid increase of industrial and domestic wastes polluting all the components of the natural environment: the atmosphere, water bodies, soils and subsoils.