Treatment of nitrate contaminated water using an electrochemical method.

Today very many wetlands are built, as are other elements in sustainable urban drainage systems. The principles of the design are, however, more art than science. At best they are designed from experience. There is a need for guidelines and simple explanations. The book Wetland systems to control urban runoff, by Miklas Scholz, tries to fill that gap with a very engineering approach. The book covers most aspects of sustainable urban drainage systems, but with an emphasis on wetlands for water treatment. The book is meant to be a text book at undergraduate level, but is also aimed at practicing engineers. The book consists of 32 chapters, of which most of them can be read separately. The title of the book is a little misleading, since the first part of the book is basic sanitary engineering, including methods for waste water engineering and treatment of drinking water described from a civil engineering approach. Of the first 23 chapters, only one is directly devoted to wetlands. The basic principles of water treatment are given to make it possible for the reader to see how wetlands function in comparison to conventional waste water treatment plants. This is likely to be appreciated by the undergraduate student, but as an experienced engineer one would probably prefer to have all wetlandspecific processes in the chapters devoted only to wetlands. However, the general review of water in a city environment does not include storm water drainage, which means that those who do not have knowledge of storm water design must read up on this before they can use the information on sustainable urban drainage system given in the last sections of the book. Also basic information about natural wetlands is lacking, such as which types there are, water balance, and interaction with groundwater; and what the hydrological function and resident time in a wetland are when the water level is high as compared to when it is low. The first part of the book, where wetlands is only included to a minor extent, is general. In the second part, wetlands are the focus of eight chapters in which six different ways of using wetlands are given, referring in detail to case studies performed by the author, and showing strategies to choose the most appropriate elements to be used in sustainable urban drainage systems in Glasgow and Edinburgh, and a methodology of how to predict the performance of a wetland. The six cases are: wetlands to improve stream water, control of roof runoff using ponds, wetlands for treating road runoff, wetland upstream belowground detention, infiltration wetland system, and natural riparian peatland for treating diffuse pollution. The experience gained from these studies is of value for the engineer who needs to design a wetland – pond infiltration system. Such studies are not often reported. However, since there is not much attempt at generalization (which maybe is not possible), he or she must still base the design on information from other sources. The text would have benefited if the principles of different constructed wetlands had been shown in figures in a general chapter; nor are different elements of sustainable urban drainage systems shown in figures. Discussions of how the different systems function during very high and very low flows are missing. As a text book in sanitary or ecological engineering the book is well written and easy to read, although it is completely lacking in figures and references. The second part with case studies and many references, is useful for practicing engineers, since there is information not found elsewhere, but it requires that the reader has knowledge from other sources about wetlands and stormwater systems.

Wetland systems to control urban runoff

Permeable pavement (PP) systems provide opportunities to mitigate the impacts of urbanization on receiving water systems by providing at source treatment and management of stormwater. However, they do not receive mainstream use throughout much of Canada and the USA because of a lack of local guidance documents, demonstration projects and performance data. Studies have repeatedly shown that PPs attenuate stormwater flows by reducing volume and frequency of stormwater flows, reducing and delaying peak flow rates, and increasing flow durations. PP systems have been shown to improve stormwater quality by reducing stormwater temperature, pollutant concentrations and pollutant loadings of suspended solids, heavy metals, polyaromatic hydrocarbons, and some nutrients. This review is intended as a comprehensive summary of the current state of knowledge of the environmental performance of PP systems. Published research is synthesized to examine the hydrologic performance, impacts to water quality, longevity and functionality and maintenance needs of PP systems. Where appropriate, the limitations of current knowledge are discussed and emerging and future research needs are presented. The intent of this review is to provide stakeholders in stormwater management with the critical information that is needed to foster acceptance of PPs as a viable alternative to traditional systems.

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Review of environmental performance of permeable pavement systems: state of the knowledge

Electrochemical treatment of nitrate ions was attempted using different catalysts on the cathode in bioelectrochemical denitrification systems. The carbon cathode coated by biofilm (biocathode) could remove 91 % of nitrate ions at 1.0 V, which was almost same as the Pt-coated electrode (90 %). The exchange current density of biocathode was 0.0083 A/m2, which was almost 22 times higher than with an abiotic plain carbon cathode. The formation of intermediate products in nitrate reduction varied depending on the cell voltage. At 0.5 V, a large portion of nitrate was converted to ammonia, but at more increased cell voltage (0.7 and 1 V) a high amount of nitrite ions was found with little ammonia formation in cathodic solution. The maximum nitrate removal rate was 0.204 mg NO3-N/cm2d by biocathode, while plain carbon paper showed only 0.176 mg NO3-N/cm2d. Electrochemical analysis of chronoamperometry showed a higher stable current generation for biocathode (3.1 mA) and Pt-coated cathode (2.8 mA) as compared to plain carbon (0.6 mA) at 0.7 V of poised voltage.

Nitrate reduction with biotic and abiotic cathodes at various cell voltages in bioelectrochemical denitrification system

Ecosystem services from turfgrass landscapes

Impervious surfaces have long been implicated in the decline of watershed integrity in urban and urbanizing areas. Porous pavement is one solution to mitigating the problem of stormwater runoff problems. In this research, three available porous pavement systems were investigated to evaluate their infiltration capability of precipitation. Experiments were conducted to simulate different kinds of porous pavements having different sub-base materials in different cells. The discharge volumes were monitored from each cell, and the relationship between rainfall intensity, outflow and outflow duration was analyzed. Results show that these three porous pavements increased infiltration and decreased runoff. The optimum thickness of the porous pavement was 31 cm, which consisted of a 6 cm top layer of porous concrete and a 25 cm sub-base (10 cm concrete without sand and 15 cm aggregate base). Furthermore, under a rainfall rate of 59.36 mm/h, the runoff coefficient of the above porous pavement was zero, while the coefficient of the impervious pavement was 0.85. These results provide a clear indication of the value of porous pavement systems for broad expanses of the human engineered environment.

Experimental study on rainfall-runoff relation for porous pavements

Water pollution and water shortage are two of the most important environmental problems in Beijing, China. Water quality of rainfall from July to August 2011 and runoff from a felt roof and an asphalt road were analyzed chemically and further investigated because these are potential sources for augmenting city supplies. Results indicate that chemical oxygen demand (COD Cr ), total phosphorus (TP), total nitrogen (TN), and ammonia nitrogen (NH 4 + -N) concentrations of initial runoff from roofs and roads all exceeded the Class V surface water quality standard developed by the Ministry of Environmental Protection of the People9s Republic of China (MEP). COD Cr concentration from road surfaces was more than 313.55 mg/L at the initial runoff stage, decreasing asymptotically to lower levels with increased rainfall duration. There is strong correlation between COD Cr , TP, TN concentrations and that of total suspended solids in road runoff. Runoff from roofs, after treatment by grid filter, flocculation and sedimentation, can be used as city municipal and domestic water except during the initial runoff stage. However, runoff from road surfaces cannot be directly reused. For city planning, this conclusion may benefit the promotion of rainwater as a renewable water supply, and avoid flooding and water scarcity.

Comparing urban runoff quality of a felt roof and an asphalt road in Beijing

Impacts of climate change and human activities on vegetation NDVI in China’s Mu Us Sandy Land during 2000–2019

Removal of chemical oxygen demand and dissolved nutrients by a sunken lawn infiltration system during intermittent storm events.

Electrochemical denitrifacation was studied for simultaneous reduction of nitrate and oxidation of by-products (ammonia and nitrite) on brass(Cu62Zn38) cathode and DSA(Ti/IrO
 2
-Pt) anode. In the presence of 0.50 g/L NaCl and 0.5g/L Na
 2
SO
 4
 as supporting electrolyte, the NO
 3
 -
-N decreased from 50.0 to 9.8 mg/L after 240 min electrolysis; no ammonia and nitrite were detected in the treated solution. The reduction capability of the brass cathode has been investigated in the range of potentials between 0.0 and -2.0 V vs. SCE with the Cycling Volt-ampere Methode(CVM). The brass cathode exhibited a high electrocatalytic activity for the reduction of NO
 3
 -
.

Lizhu Hou

Papers

Experimental study on rainfall-runoff relation for porous pavements

Comparing urban runoff quality of a felt roof and an asphalt road in Beijing

Impacts of climate change and human activities on vegetation NDVI in China’s Mu Us Sandy Land during 2000–2019

Removal of chemical oxygen demand and dissolved nutrients by a sunken lawn infiltration system during intermittent storm events.

Electrochemical Removal of Nitrate Ion on Brass Cathode and DSA Anode