Residual effect of UV radiation on Microcystis aeruginosa and Escherichia coli K12 A/ (F ϩ ) was studied under various conditions to examine if the formation of hydrogen peroxide (H 2 O 2 ) and hydroxyl radical (OH • ) can explain the residual biocidal action of UV radiation. Survival of test organisms, that is,M . aeruginosa and E. coli K12 A/ (F ϩ ), in UV-irradiated synthetic water was monitored to assess the residual effect after the UV radiation. Synthetic water with various compositions was used to understand the role of transition metals and photosensitizing organic molecules in producing the residual biocidal action. Ultraviolet-irradiated synthetic water containing a photosensitizing element and ferric ion (Fe 3ϩ ) showed residual biocidal effect for more than 7 days. No residual effect was observed in the absence of any photosensitizing element. A close relationship was observed between the residual effect and the formation of hydrogen peroxide in the UV-irradiated water. Scavenging of hydrogen peroxide and hydroxyl radical from the UV-irradiated water signifi cantly reduced the residual biocidal action. Ultraviolet-irradiation of synthetic water containing ferric ion was found to promote the formation of ferrous ion (Fe 2ϩ ). Because ferrous ion can produce reactive species in the presence of hydrogen peroxide, transition metals and hydrogen peroxide are believed to play a key role in producing the residual effect of UV radiation through the formation of reactive species, for example, hydroxyl radical. Water Environ. Res., 74, 248 (2002). Materials and MethodsReagents and Chemicals. N,N-Bis(2-hydroxyethyl) glycine was obtained from Wako Co. (Osaka, Japan). Scopoletin (7-hydroxy-6-methoxy-1,2-benzopyrone), horseradish peroxidase, and bovine-lever catalase were obtained from Sigma Chemical Co. (St.

The paper analyses a community development project based in Jhenaidah, Bangladesh, which evolved through broadening social capital among slum communities and formal institutions in order to bring positive socio-spatial changes in the neighborhoods. Till date, nine disadvantaged communities have formed a network for city-wide community development, have started to build and manage their own funds, built better houses for themselves, and through this process have managed to draw attention and support from the local government. Started by a small group of architects and a local NGO in 2015, and still broadening its scopes, this project can be regarded as a successful example of people-led development initiative, especially in a context where most development projects exercise limited participatory values and are dominated by unequal power dynamics. Hence issues like scaling up and economic sustainability still concern those, who can see the community-driven development process with an unbiased attitude. The overarching goal of this article is to sketch out these issues with the help of empirical understandings from the field and theoretical findings from literature on social innovation and power in planning in order to understand how to work balance between local and institutional management of projects in order to avoid perceiving bottomup and top-down initiatives in a dualistic manner.

No abstract

Presence of wastewater particles is often cited as the reason for failure of UV-irradiation to inactivate targeted organisms to desired level. However, till now there is no method to directly assess the inactivation of particle-associated indicator organisms after UV-irradiation. In this study, we tried to establish a method to identify viable bacteria within wastewater particles. This method was then used to distinguish between particle-associated viable and non-viable bacteria after UV-irradiation. The objective was to assess the fraction of particles of different sizes that are associated with coliform bacteria and to analyze the impact that these particles may have on the residual coliform concentration after UV-radiation. We found that fluorescent in-situ hybridization (FISH) in conjugation with Direct viable count can be effectively used for identification and counting of particle associated Enterobacteriaceae. The method can also successfully distinguish viable bacteria after UV-radiation. We found that only 2 percent of the total coliforms in the supernatant from the secondary clarifier of the Shibaura water treatment plant is associated with particles. Association of coliforms were maximum for the particle size ranging from 41-µm to 80-µm. It was also found that UV-radiation can effectively penetrate through most of the waste water particles.