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The Horizontal Subsurface Flow (HSSF) reed bed is the most widely used concept of constructed wetland. (Vymazal, 2005). Typically rectangular in design, wastewater is fed at the inlet and passes through the media below the surface in a horizontal path before discharging at the outlet. This basic classification of a HSSF wetland is based on the hydraulic flow pattern through the system. Designed to achieve maximum performance from the system, the optimal design characteristics for HSSF have evolved separately in each country, due to the unique set of conditions (i.e. extremes of temperature, high rainfall, etc), in order to maximise their removal efficiencies and keep the area to a minimum. (Akratos & Tsihrintzis, 2007). Climatic conditions are the main reason for HSSF bed design differences in different parts of the world, with each country having its own set of design guidelines. The Constructed Wetland Association Database lists 1025 reed bed sites in the UK, of which 893 are HSSF. HSSF reed beds have been used for tertiary sewage treatment in the UK since the 1980΄s. Over this time, the HSSF concept has been widely studied and the design criteria adapted in light of practical experience gained from the operation of numerous systems in order to achieve optimum treatment efficiency. Lessons have been learned from failing systems leading to the ˵designing out″ of problem areas. As well as achieving maximum performance and reducing the footprint, the most important factor in designing constructed wetlands today is to prolong the life of beds by minimising clogging of systems. [ABSTRACT FROM AUTHOR]

The sequencing batch reactor (SBR) is a fill-and-draw activated sludge system for wastewater treatment. SBR systems have been successfully used to treat both municipal and industrial wastewater. They are uniquely suited for wastewater treatment applications characterized by low or intermittent flow (IF) conditions. This chapter discusses the following aspects of the process: background and process description, proprietary SPR processes, description of a treatment plant using an SBR, applicability, advantages and disadvantages design criteria, process performance, operation and maintenance, cost, and packaged SBR for onsite systems. [ABSTRACT FROM AUTHOR]

This article introduces design criteria for e-learning systems based on implications from the disciplines of educational science, software engineering, and information security. Theoretical realization concepts to implement stated requirements are discussed. A conceptual implementation of a proxy server realized within this research project is also presented. This proxy server demonstrates the feasibility of stated concepts and enables outsourcing of security-related tasks to an automated process. [ABSTRACT FROM AUTHOR]

There are a range of different usability evaluation methods: both analytical and empirical. The appropriate choice is not always clear, especially for new technologies. In-car navigation systems are an example of how multimodal technologies are increasingly becoming part of our everyday life. Their usability is important, as badly designed systems can induce errors resulting in situations where driving safety may be compromised. In this paper we use a study on the usability of a navigation device when the user is setting set up an itinerary to investigate the scope of different classes of approach. Four analytical and one empirical techniques were used to evaluate the usability of the device. We analyse the results produced by the two classes of approach – analytical versus empirical – and compare them in terms of their diversity and the insight they provide to the analyst in respect to the overall usability of the system and its potential improvement. Results suggest a link between genotypes and the analytical class of approach and phenotypes in the empirical class of approach. We also illustrate how the classes of approach complement each other, providing a greater insight into the usability of a system. [ABSTRACT FROM AUTHOR]