As pollution becomes one of the biggest environmental challenges of the twenty-first century, pollution of water threatens the very existence of humanity, making immediate action a priority. The most persistent and hazardous pollutants come from industrial and agricultural activities; therefore, effective treatment of this wastewater prior to discharge into the natural environment is the solution. Advanced oxidation processes (AOPs) have caused increased interest due to their ability to degrade hazardous substances in contrast to other methods, which mainly only transfer pollution from wastewater to sludge, a membrane filter, or an adsorbent. Among a great variety of different AOPs, a group of electrochemical advanced oxidation processes (EAOPs), including electro-Fenton, is emerging as an environmental-friendly and effective treatment process for the destruction of persistent hazardous contaminants. The only concern that slows down a large-scale implementation is energy consumption and related investment and operational costs. A combination of EAOPs with biological treatment is an interesting solution. In such a synergetic way, removal efficiency is maximized, while minimizing operational costs. The goal of this review is to present cutting-edge research for treatment of three common and problematic pollutants and effluents: dyes and textile wastewater, olive processing wastewater, and pharmaceuticals and hospital wastewater. Each of these types is regarded in terms of recent scientific research on individual electrochemical, individual biological and a combined synergetic treatment.

Electrochemical advanced oxidation and biological processes for wastewater treatment: a review of the combined approaches.

We use cosmogenic nuclide-derived denudation rates from in situ–produced 10 Be in river sediment to determine sediment production rates for the central Amazon River and its major tributaries. Recent developments have shown that this method allows calculating denudation rates in large depositional basins despite intermediate sediment storage, with the result that fluxes of the sediment-producing hinterland can now be linked to those discharged at the basins’ outlet. In rivers of the central Amazonian plain, sediment of finer grain sizes (125–500 μm) yields a weighted cosmogenic nuclide-derived denudation rate of 0.24 ± 0.02 mm/yr that is comparable to the integrated rate of all main Andean-draining rivers (0.37 ± 0.06 mm/yr), which are the Beni, Napo, Mamore, Ucayali, and Maranon rivers. Coarser-grained sediment (>500 μm) of central Amazonian rivers is indicative of a source from the tectonically stable cratonic headwaters of the Guyana and Brazilian shields, for which the denudation rate is 0.01–0.02 mm/yr. Respective sediment loads can be calculated by converting these cosmogenic nuclide-derived rates using their sediment-producing areas. For the Amazon River at Obidos, a sediment production rate of ∼610 Mt/yr results; non-Andean source areas contribute only ∼45 Mt/yr. A comparison with published modern sediment fluxes shows similarities within a factor of ∼2 with an average gauging-derived sediment load of ∼1000 Mt/yr at Obidos, for example. We attribute this similar trend in cosmogenic versus modern sediment loads first to the absence of long-term deposition within the basin and second to the buffering capability of the large Amazon floodplain. The buffering capability dampens short-term, high-amplitude fluctuations (climatic variability in source areas and anthropogenic soil erosion) by the time the denudation rate signal of the hinterland is transmitted to the outlet of the basin.

Sediment production and delivery in the Amazon River basin quantified by in situ–produced cosmogenic nuclides and recent river loads

Pirate modernity: Delhi's media urbanism, by Ravi Sundaram, Abingdon, Routledge, 2010, 228 pp., ISBN 978-81-89643-07-2 In the preface of the book, Ravi Sundaram writes, ‘(r)ather than media analysi...

Pirate modernity: Delhi's media urbanism

Some respite for India's dirtiest river? Examining the Yamuna's water quality at Delhi during the COVID-19 lockdown period.

Comparison is now taken as vital to the constitution of knowledge about cities and urbanism. However, debate on comparative urbanism has been far more attentive to the merits of comparisons between...

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Cities within cities : intra-urban comparison of infrastructure in Mumbai, Delhi and Cape Town.

This article examines the making of a modern colonial city through the rhetoric of ‘improvement’ and ‘progress’ in relation to water. The reference is to the history of water in the city of Delhi and what may be called ‘the first science of environment’ in a colonial urban context, with a focus not so much on the ‘extent’ of water supply and drainage, and its (in)adequacy in the colonial city, as on concerns around the ‘(im)purity’ of water, narratives of pollution, technologies of purity and the transformations they effected in a colonial context. In doing so it hopes to build upon a rich tradition of writings on urban water, its modernisation as also its location within a colonial regime, being suggestive of a framework in which we may consider water both as infrastructure and as environment, as much a network of pipes and drains as matters of pollution and well-being, as much a story of the search for and protection of the source as of the fate of the sink into which it ultimately flows.

From source to sink ‘Official’ and ‘improved’ water in Delhi, 1868–1956

This essay examines the presence of Yamuna in the city of Delhi, from two perspectives: (i) understanding riverscapes as simultaneously aquatic and terrestrial and (ii) understanding these as conjoining issues of environment and technology. With events over the course of the last century as its backdrop, the essay focuses on the last few decades of the twentieth century, to examine the relation of land and river in Delhi; the interface of people and projects, especially the issue of slums; and the risks posed to the river on account of waste and pollution. All these featured prominently in the events leading up to the staging of the Commonwealth Games in Delhi in October 2010, which provides the most immediate context for this essay. In conclusion, I propose that the current strategies of rejuvenating the river are limited, often anti-poor and far from sustainable.

A river and the riverfront: Delhi’s Yamuna as an in-between space

This article seeks to unpack the administrative and knowledge practices through which the community of Depressed Classes/Scheduled Castes was delineated in colonial Bihar. It does so by examining b...

Awadhendra Sharan

Papers

From source to sink ‘Official’ and ‘improved’ water in Delhi, 1868–1956

A river and the riverfront: Delhi’s Yamuna as an in-between space

From caste to category: Colonial knowledge practices and the Depressed/Scheduled Castes of Bihar