Basics of qualitative research: Grounded theory procedures and techniques

The term ''urban stream syndrome'' describes the consistently observed ecological degra- dation of streams draining urban land. This paper reviews recent literature to describe symptoms of the syndrome, explores mechanisms driving the syndrome, and identifies appropriate goals and methods for ecological restoration of urban streams. Symptoms of the urban stream syndrome include a flashier hy- drograph, elevated concentrations of nutrients and contaminants, altered channel morphology, and reduced biotic richness, with increased dominance of tolerant species. More research is needed before generaliza- tions can be made about urban effects on stream ecosystem processes, but reduced nutrient uptake has been consistently reported. The mechanisms driving the syndrome are complex and interactive, but most impacts can be ascribed to a few major large-scale sources, primarily urban stormwater runoff delivered to streams by hydraulically efficient drainage systems. Other stressors, such as combined or sanitary sewer overflows, wastewater treatment plant effluents, and legacy pollutants (long-lived pollutants from earlier land uses) can obscure the effects of stormwater runoff. Most research on urban impacts to streams has concentrated on correlations between instream ecological metrics and total catchment imperviousness. Recent research shows that some of the variance in such relationships can be explained by the distance between the stream reach and urban land, or by the hydraulic efficiency of stormwater drainage. The mech- anisms behind such patterns require experimentation at the catchment scale to identify the best management approaches to conservation and restoration of streams in urban catchments. Remediation of stormwater impacts is most likely to be achieved through widespread application of innovative approaches to drainage design. Because humans dominate urban ecosystems, research on urban stream ecology will require a broadening of stream ecological research to integrate with social, behavioral, and economic research.

https://www.jstor.org/stable/10.1899/04-028.1

The urban stream syndrome: current knowledge and the search for a cure

Membranes have an increasingly important role in alleviating water scarcity and the pollution of aquatic environments. Promising molecular-level design approaches are reviewed for membrane materials, focusing on how these materials address the urgent requirements of water treatment applications.

Materials for next-generation desalination and water purification membranes

As photovoltaic penetration of the power grid increases, accurate predictions of return on investment require accurate prediction of decreased power output over time. Degradation rates must be known in order to predict power delivery. This article reviews degradation rates of flat-plate terrestrial modules and systems reported in published literature from field testing throughout the last 40 years. Nearly 2000 degradation rates, measured on individual modules or entire systems, have been assembled from the literature, showing a median value of 0·5%/year. The review consists of three parts: a brief historical outline, an analytical summary of degradation rates, and a detailed bibliography partitioned by technology. Copyright © 2011 John Wiley & Sons, Ltd.

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Photovoltaic Degradation Rates—an Analytical Review

In the last few decades, pharmaceuticals, credited with saving millions of lives, have emerged as a new class of environmental contaminant. These compounds can have both chronic and acute harmful effects on natural flora and fauna. The presence of pharmaceutical contaminants in ground waters, surface waters (lakes, rivers, and streams), sea water, wastewater treatment plants (influents and effluents), soils, and sludges has been well doccumented. A range of methods including oxidation, photolysis, UV-degradation, nanofiltration, reverse osmosis, and adsorption has been used for their remediation from aqueous systems. Many methods have been commercially limited by toxic sludge generation, incomplete removal, high capital and operating costs, and the need for skilled operating and maintenance personnel. Adsorption technologies are a low-cost alternative, easily used in developing countries where there is a dearth of advanced technologies, skilled personnel, and available capital, and adsorption appears to be the most broadly feasible pharmaceutical removal method. Adsorption remediation methods are easily integrated with wastewater treatment plants (WWTPs). Herein, we have reviewed the literature (1990-2018) illustrating the rising environmental pharmaceutical contamination concerns as well as remediation efforts emphasizing adsorption.

Pharmaceuticals of Emerging Concern in Aquatic Systems: Chemistry, Occurrence, Effects, and Removal Methods.

The aim of this research was to develop an inventory of technologies for the collection, treatment, storage, and distribution of general urban stormwater runoff (runoff from all types of urban areas, including roads, car parks etc.) and, where current knowledge allows, provide interim guidance on stormwater re-use implementation. An extensive review of existing stormwater re-use systems was carried out, focussing on the eastern seaboard of Australia and South Australia (a few international schemes were also included). Seventeen systems were selected and studied in detail. Lessons were learned with respect to sizing, technique selection and design for the various functions, performance, operation and maintenance, integration into the total water cycle of reuse systems and other implementation issues, and costs and benefits. There are no statutory obligations or guidelines specific to stormwater re-use and the general recommendation that wastewater re-use guidelines be referred to is not entirely inappropriate, since these two water streams are very different in terms of both supply and quality. At this stage, stormwater re-use is largely restricted to smaller scale sites, and is mainly used for purposes with low potential for human contact. Collection and storage are still based on conventional methods while treatment is mainly based on techniques typically incorporated into Water-Sensitive Urban Design (WSUD). It appears that the same design methods are used for re-use schemes as for stormwater pollution control alone. This may cause some problems since the stormwater pollution control systems are not currently designed to deliver high quality water; in particular the reliability of treatment may be an issue. The development of innovative techniques designed specifically for stormwater reuse is required. Performance modelling also needs further research. Performance results were somewhat limited, however developers, operators and regulators appear to be satisfied with the schemes' initial performances, and the public response has been positive. There are multi-benefits that may be achieved through stormwater re-use, including reduced demand on potable supplies, pollution control, decreased stormwater runoff, and habitat protection. However, many of these benefits are difficult to cost, and a novel approach with well structured methodology should be developed to assess benefits of re-use schemes. If the costs and benefits of re-use schemes can be shown to compare favourably with the costs and benefits of conventional practices, this will provide a good deal of incentive to overcome other obstacles to widespread adoption of stormwater recycling.

Integrated stormwater treatment and re-use - inventory of Australian practices

The Performance of Vegetated Swales for Urban Stormwater Pollution Control

"Triple-bottom-line" assessment of urban stormwater projects.

Biochar particle size and amendment rate are more important for water retention and weight of green roof substrates than differences in feedstock type

Model calibration and sensitivity analysis of stormwater models are required to assess model performance; it is very unlikely that non-calibrated models will lead to reasonable results. The aim of this paper is to present results of the calibration and sensitivity analysis of the key parameters used in flow modelling by MUSIC and parameters of a simple stormwater quality model. The assessment of the models is undertaken using a Monte Carlo Markov Chain approach. We describe the models' performance, provide information on their sensitivity to parameters and also discuss the correlation between these parameters. This work will help practitioners to understand importance of the MUSIC parameters that they usually use without calibration. The information reported in the results will also help to guide future development of stormwater quality models and the data needed to support it.

Tim D. Fletcher

Papers

Integrated stormwater treatment and re-use - inventory of Australian practices

The Performance of Vegetated Swales for Urban Stormwater Pollution Control

"Triple-bottom-line" assessment of urban stormwater projects.

Biochar particle size and amendment rate are more important for water retention and weight of green roof substrates than differences in feedstock type

Calibration and sensitivity analysis of urban drainage models: MUSIC rainfall/runoff module and a simple stormwater quality model