S. K. Bag

Use of human urine in phytoplankton production as a tool for ecological sanitation

Measurements of primary productivity of phytoplankton and enumeration of the counts of coliform and heterotrophic bacteria (HB) were made in the water of 12 experimental tanks used for 3 treatments and control in triplicate as follows: (a) fresh human urine (0.02%), (b) stored human urine (0.02%), (c) mixed urine of fresh and stored human urine (0.02%) and (d) control without input of urine. The gross primary productivity of phytoplankton was highest in the stored urine treated tanks (508 mg C m(-2) h(-1)) followed by fresh urine (353 mg C m(-2) h(-1)), mixed urine (303 mg C m(-2) h(-1)) and control (215 mg C m(-2) h(-1)). Similar was the response of net primary production of phytoplankton. The mean count of HB observed in stored urine fed tanks was significantly higher (59-184%) than the remaining urine fed treatments. The mean count of Escherichia coli did not differ from urine treated tanks to control implying the good quality of water. The concentration of dissolved oxygen of water (7.6 to 12.8 mg L(-1)) in these tanks remained satisfactory for aquaculture. The mean concentration of ammonium-N observed in fresh urine treated tanks was more than 10 times higher than the remaining treatments employed. In contrast, the level of phosphate and electrical conductivity in the stored urine treated tanks were significantly higher than the remaining treatments. It is proposed that stored urine with a significantly reduced load of E. coli might be an effective low cost liquid fertilizer for algal biomass production.

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.

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.

Prevalence of trypanosomes from Clarius batrachus (Linnaeus) of Purba Medinipur, West Bengal, India

Haemoflagellates of the genus Trypanosoma Gruby, 1843 are prevalent in fresh water fishes and are transmitted by leech. A total of 133 Clairus batrachus were examined for haemoflagelates. The fishes were collected from ponds and water bodies of Purba Medinipur district, West Bengal, India, from January, 2006 to July, 2007. The slides were prepared taking blood from both males (97) and females (36). It was found that only 19 out of 36 (52.78%) females and 31 out of 97 (31.95%) males were infected. Thus females were recorded with a higher prevalence of trypanosome infection than males. There was a significant difference (P<0.05) in the infection rate with trypanosomes in males and females.