Time filter

Source Type

Warrington, United Kingdom

Jennings A.A.,Case Western Reserve University | Hanna A.,MWH Global Inc
International Journal of Environment and Waste Management | Year: 2010

This manuscript describes a database of US state regulatory guidance values assembled to examine the guidance applied to the most commonly regulated surface soil contaminants. Guidance values were identified for 994 different contaminants, but there is considerable variability in the number of contaminants regulated by each state and in the values applied to contaminants. Guidance values for the 40 most-regulated organics vary by an average of four orders of magnitude. Details are presented for guidance applied to naphthalene, benzene, toluene, ethylbenzene, dimethylbenzene, Lindane, phenol, trichloroethylene, benz[a]anthracene, and methoxychlor to illustrate statistical properties of value variation. Copyright © 2010 Inderscience Enterprises Ltd.

Cherchi C.,MWH Americas Inc. | Badruzzaman M.,MWH Americas Inc. | Oppenheimer J.,MWH Americas Inc. | Bros C.M.,MWH Global Inc | And 2 more authors.
Journal of Environmental Management | Year: 2015

Holistic management of water and energy resources is critical for water utilities facing increasing energy prices, water supply shortage and stringent regulatory requirements. In the early 1990s, the concept of an integrated Energy and Water Quality Management System (EWQMS) was developed as an operational optimization framework for solving water quality, water supply and energy management problems simultaneously. Approximately twenty water utilities have implemented an EWQMS by interfacing commercial or in-house software optimization programs with existing control systems. For utilities with an installed EWQMS, operating cost savings of 8-15% have been reported due to higher use of cheaper tariff periods and better operating efficiencies, resulting in the reduction in energy consumption of ~6-9%. This review provides the current state-of-knowledge on EWQMS typical structural features and operational strategies and benefits and drawbacks are analyzed. The review also highlights the challenges encountered during installation and implementation of EWQMS and identifies the knowledge gaps that should motivate new research efforts. © 2015 Elsevier Ltd.

Weng S.,Johns Hopkins University | Luo Y.,U.S. Department of Agriculture | Li J.,U.S. Department of Agriculture | Li J.,Huazhong Agricultural University | And 4 more authors.
Food Control | Year: 2016

For the fresh-cut produce industry, a critical area of concern is potential pathogen cross-contamination during wash operations when wash water is reused and re-circulated in wash systems continuously imputed with fresh-cut produce. However, little research has focused on the chemical properties of wash water. Organic input from residual soil and vegetable material deteriorates water quality and creates increasing chlorine demand within this wash water. This study evaluated the origins of chlorine demand input and chlorine decay kinetics of fresh-cut produce wash water. Using a model system, vegetable juice released per kg of processed produce for shredded romaine lettuce, shredded iceberg lettuce, shredded carrot and baby spinach was 82.1 mL/kg, 94.5 mL/kg, 158 mL/kg, and 2.26 mL/kg, respectively. Batch water analysis revealed a rapid reaction between constituents in the wash water and chlorine where over a 90 min observation period, 50% of chlorine demand occurred within first 5 min, underscoring the challenge for any water treatment process to reduce chlorine demand once vegetables are deposited into washing systems. Moreover, the results also showed sustained chlorine demand over 90-min periods, indicating an accumulative effect on chlorine consumption with continuous organic input. Additionally, HPLC-SEC analysis showed that the constituents contributing to chlorine demand are predominantly dissolved small molecules (<3400 Da), which will challenge water reuse treatment approaches. This study provides quantitative information of chlorine demand origins and chlorine decay kinetics in wash water and provides baseline data critical for integrating water reuse in the fresh produce processing industry. © 2015 Elsevier Ltd.

Adelman M.J.,MWH Global Inc | Weber-Shirk M.L.,Cornell University | Cordero A.N.,Accenture | Maher W.J.,Cauldwell Wingate | Lion L.W.,Cornell University
Journal of Environmental Engineering (United States) | Year: 2013

Infrastructure for water treatment faces numerous challenges around the world, including the high failure rate of digital, electronic, pneumatic, and mechanical control systems due to their large number of components and their dependency on proprietary parts for repair. The development of more efficient, reliable, easily repaired water treatment controls that rely on simple fluidics rather than on complex systems has the potential to significantly improve the reliability of drinking water treatment plants, particularly for cities and towns in developing countries. A stacked rapid sand filter (SRSF) has been proposed as a more robust and sustainable alternative to conventional rapid sand filters because each filter can backwash at the same flow rate used for filtration without requiring pumps or storage tanks. While the concept of this filter has been demonstrated in previous studies, this paper presents a novel control system for the SRSF based on fluidics that eliminates the need for mechanized controls. The water level in the filter is regulated by a siphon pipe, which conveys flow during backwash and which contains an air trap to block flow during filtration. The state of the siphon pipe and the ensuing state of the filter are controlled by one small-diameter air valve. This fluidic control system was tested in pilot-scale experiments, which demonstrated its ability to set the mode of operation of the filter and served as the basis for the derivation of design equations. In addition, the first full-size SRSF was built at a municipal water plant in Honduras using this fluidic control system, which provided a full-scale demonstration of its effectiveness. This simple and robust control system shows promise as part of a sustainable rapid sand filtration process. © 2013 American Society of Civil Engineers.

MWH Global Inc. | Date: 2005-11-08

Software interface which integrates third party software to support infrastructure capital improvement programs for utilities.

Discover hidden collaborations