Suchergebnisse

AbstractThis paper reviews operational and experimental disinfection techniques for the removal of pathogens from sewage and secondary effluent prior to marine discharge. Disinfection options considered include chlorine (hypochlorite, chloramines, OSEC), ultraviolet light (UV), ozone, chlorine dioxide, bromine chloride, peracetic acid (PAA) and gamma irradiation. A comparison of alternative systems is made in terms of their inactivation efficiency, safety, environmental impact and cost. Budget costs were obtained from chemical and equipment suppliers for the disinfection of a theoretical case‐study, to enable a direct cost‐comparison to be made.

ABSTRACTFaced with increasing pressures on environmental issues, municipal and industrial planners must incorporate changing technology into planning processes. Conventional approaches to wastewater treatment plant design severely limit the ability of the designer to evaluate alternative design configurations. This paper suggests that computer simulation techniques can provide solutions to many of the problems which confront a designer. A simulation model of a hypothetical sewage treatment plant is described, and some of the design trade‐offs that can be evaluated with the model are presented.

You don't think about it until it breaks -- What is a plumber? -- What is a sewage worker? -- History of plumbing and sewage -- Myths and major inventions -- A day in the life of plumbers -- A day in the trenches with a sewage worker -- Homework and learning from the pros -- Big bucks for work people don't want to do -- A bright future -- Glossary -- Index.

published_or_final_version ; Public Administration ; Master ; Master of Public Administration

A Nordic project was initiated as part of an evaluation of sludge treatment processes based on the suggested new EU legislation (EC 2000REF). This report covers the different parts of the project.The project focused on sewage and sludge treatment within a broader frame of background information regarding Giardia and Cryptosporidium, especially the relationship between the risk of transmission and the risk of aquiring infections from the environment. The objectives were further to exemplify the occurrence and viability of Giardia and Cryptosporidium through investigations in raw sewage and untreated or treated sludge from two sewage treatment plants.This report includes: 1. A literature review of Giardia and Cryptosporidium in the society and the environment. 2. A field study of occurrence and removal of the protozoa during wastewater and sludge treatment and,3. A laboratory study to further evaluate the efficiency of sludge treatment at various temperatures.

published_or_final_version ; Environmental Management ; Master ; Master of Science in Environmental Management

ABSTRACTWhen completed, the sewage‐treatment works at St. Martin will serve nearly a third of Mauritius'1.1 million population. In addition to protecting the marine environment, it will provide a valuable source of water to supplement irrigation supplies to west‐coast sugar‐cane plantations.This paper explains (i) the treatment‐process selection which favoured conventional activated sludge over extended aeration, (ii) the need for nutrient removal, (iii) the choice of UV treatment for disinfection, and (iv) the problem of dye discharges from the textile industry. It also describes the complexity of the control system which is designed to (a) supply tertiary effluent to the irrigation canals blended with surface‐water supplies to avoid sodium accumulation in the soils. (b) avoid flooding of the canals, and (c) provide an emergency stormoverflow discharge via the same common outfall pipe to the sea.

Sewage sludge use in agriculture is promoted by the European Union since the normative of cleaning waters related to the compulsory use of depuration plants in all cities over 2000 inhabitants was finally implemented in 2005. The University of Santiago de Compostela (USC) has been conducted long-term experiment research about the application of different sewage sludge doses in silvopastoral systems. Main results shown that sewage sludge can be successfully used as fertilizer for both tree and pasture development, with reduced toxicity for animals when plant production is considered in both very acidic and acidic-neutral soils. This paper provides an overview of the main findings in acidic soils of the long-term results after application of sewage sludge in soils.

ABSTRACTTHE 'root‐zone' sewage‐treatment proccess was introduced to the UK and Yorkshire Water in 1984, with claims that capital and operating costs were significantly less than for conventional processes. The design and construction of the experimental root‐zone bed at Holtby (which forms part of Yorkshire Water's contribution to the evaluation of the process in the UK), is described. The planting of the Phragmites, their growth and the performance of the bed are discussed. Suspended solids and BOD removal efficiencies have satisfied the predictions of the designers for the performance of a bed which is still immature, although ammonia and phosphate removals have been low. The role which is played by the reeds is considered to be minor, and it is suggested that it is too early to judge the Holtby bed either a success or a failure. The paper also discusses the problem of weed control, the importance of floor slope, maturity of the system and the use of gravel instead of soil.

ABSTRACTWithin THE LAST few years there has been a resurgence of UK interest in incineration as a sludge disposal option. However, the last plant installed in the UK represented the technology and design thinking of the 1970s and there have been significant developments since that time. These are reviewed in this paper.Especial attention is given to changes in legislation and attitudes concerning the environmental impact of incineration, and the effects on process selection. The wide range of options for the achievement of autothermic operation are itemized and a brief review of costs given.It is considered likely that incineration will have an increased role in the future, though continuing to be rather specialized. Keeping an open mind on equipment selection is urged, as is the conduct of an organized programme of work to establish process design information before going out to tender.