Search results for "environmental engineering"
showing 10 items of 2674 documents
Assessment of wastewater treatment alternatives for small communities: An analytic network process approach
2015
The selection of the most appropriate wastewater treatment (WWT) technology is a complex problem since many alternatives are available and many criteria are involved in the decision-making process. To deal with this challenge, the analytic network process (ANP) is applied for the first time to rank a set of seven WWT technology set-ups for secondary treatment in small communities. A major advantage of ANP is that it incorporates interdependent relationships between elements. Results illustrated that extensive technologies, constructed wetlands and pond systems are the most preferred alternatives by WWT experts. The sensitivity analysis performed verified that the ranking of WWT alternatives…
Pollutant removal efficiency of a pilot-scale Horizontal Subsurface Flow in Sicily (Italy) planted with Cyperus alternifolius L. and Typha latifolia …
2016
Constructed wetland systems (CWs) are developed biological technologies for the treatment and reuse of wastewater. The aims of this study were to evaluate the treatment performance of a pilot Horizontal Subsurface Flow system (HSSFs), to evaluate the reuse of treated wastewater (TWW) from CWs for the irrigation of giant reed (Arundo donax (L.)) and to assess the effects of TWW on the biomass yield of giant reed grown for pellet production. The research was carried out in Sicily (Italy) in a pilot-scale HSSFs which was fed with urban-treated urban wastewater following secondary treatment from an activated sludge wastewater treatment plant. Giant reed plots were irrigated with TWW from plante…
The use of constructed wetlands for the treatment and reuse of urban wastewater for the irrigation of two warm-season turfgrass species under Mediter…
2017
Constructed wetlands (CWs) represent low-cost technology for the treatment and reuse of wastewater in urban areas. This study aimed to evaluate the pollutant removal efficiency of a CW system and to assess the effects of irrigation using treated urban wastewater on soil and on two warm-season turf species. The research was carried out in Sicily (Italy) on a pilot-scale horizontal subsurface flow system which was fed with treated urban wastewater following secondary treatment from an activated-sludge wastewater treatment plant. The pilot system was located in an open urban park and comprised two separate parallel planted units. Experimental fields of Cynodon dactylon (L.) Pers. and Paspalum …
Testing the Modified Sediment Delivery Model (MOSEDD) at SPA2 Experimental Basin, Sicily (Italy)
2017
A new version of a spatially distributed sediment delivery model taking into account the hillslope sediment transport efficiency, named MOSEDD, is presented. This model gives estimates of basin sediment yield at event scale, which are more reliable than those obtained by the original SEDD. For SPA2 basin discretized into morphological units, four different calculation schemes of MOSEDD, including the original SEDD version, were applied. All parameterization schemes of the model were calibrated using 15 events measured at the outlet of the experimental basin in the period February 2005–February 2010. The model calibration was used to determine a relationship between the coefficient βₑ of the…
Characterizing rainfall erosivity by kinetic power-Median volume diameter relationship
2018
Abstract Kinetic power, i.e. kinetic energy per unit time and area, is the variable widely used to represent the rainfall erosivity which affects soil loss and sediment yield. This paper shows the results of an experimental investigation using the raindrop size distributions (DSDs) measured by an optical disdrometer installed at the Department of Agricultural, Food and Forestry Sciences of University of Palermo in Italy (June 2006–March 2014) and at the El Teularet experimental station in Spain (July 2015–May 2016). At first an analysis of the DSDs aggregated into intensity classes is carried out, then the measured kinetic power values are determined. The aggregated DSDs allowed to establis…
Assessing flow resistance law in vegetated channels by dimensional analysis and self-similarity
2019
Abstract In this paper experimental data collected by Kouwen et al., Wilson and Horrit, Raffaelli et al. and Carollo et al., using straight flumes having a bed covered by grass-like vegetation with different stem concentrations, were used to analyze flow resistance for flexible submerged elements. At first, the dimensional analysis and the incomplete self-similarity hypothesis was applied to deduce the flow velocity distribution and the resulting theoretical expression of the Darcy-Weisbach friction factor. Then, a relationship between the Γ function of the velocity profile and the biomechanical characteristics of vegetation, the channel slope, the Reynolds number and the flow Froude number…
Assessing theoretical flow velocity profile and resistance in gravel bed rivers by field measurements
2018
Previous studies showed that integrating a power velocity profile, deduced applying dimensional analysis and the incomplete self-similarity condition, the flow resistance equation for open channel flow can be obtained. At first, in this paper the relationship between the Gamma function of the power velocity profile, the channel slope and the Froude number, which was already empirically introduced in a previous paper, is now theoretically deduced. Then this relationship is calibrated using the field measurements of flow velocity, water depth and bed slope carried out in 101 reaches of gravel bed rivers available by literature. The proposed relationship for estimating Gamma function and the t…
How much should customers be compensated for interruptions in the drinking water supply?
2017
Water supply interruptions directly affect customers, and customers should be compensated accordingly. However, few water regulators have applied compensation policies given the difficulty of estimating the economic value of compensation to customers. In this study, a pioneering approach based on the concept of shadow prices is proposed to determine the compensation that customers should receive for unplanned water interruptions. The Chilean water industry was selected as a case study because there is an ongoing policy discussion between the use of penalties or compensation as an incentive to prevent water supply interruptions. The estimated results indicate that for 2014, the value of comp…
A model of the filling process of an intermittent distribution network
2010
In many countries, private tanks are acquired by users to reduce their vulnerability to intermittent supply. The presence of these local reservoirs modifies the user demand pattern and usually increases user water demand at the beginning of the service period depending on the tank filling process. This practice is thus responsible for the inequality that occurs among users: those located in advantaged positions of the network are able to obtain water resources soon after the service period begins, while disadvantaged users have to wait much longer, after the network is full. This dynamic process requires the development of ad hoc models in order to obtain reliable results. This paper discus…
Measuring the eco-efficiency of wastewater treatment plants under data uncertainty
2018
Abstract Eco-efficiency assessment is a useful tool for improving the sustainability of wastewater treatment plants (WWTPs). However, it is a complex task that requires the integration of several performance indicators into a single index. Data envelopment analysis (DEA) is established as a highly effective methodology for achieving this as it permits the integration of the service value, resource consumption and environmental impact variables as the desirable outputs, inputs and undesirable outputs, respectively. However, traditional DEA models omit uncertainties in the data that are likely to result in biased conclusions. This study pioneers the assessment of the eco-efficiency of WWTPs w…