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Podcast Taking infrastructure discusses the industry's hot topics, key projects and groundbreaking innovation. Our offices We have offices around the world. Find one near you. Our offices. For localized country information, please click below Discover more. Delivering a better world through program management United by a common purpose to deliver on this vision. Surveys are con- ducted by U. EPA, a are reported in Tables and Suspended solids Screening 5 Grit removal 5 Sedimentation 5 High-rate clarification 5 Flotation 5 Chemical precipitation 6 Depth filtration II Surface filtration lI Biodegradable organics Aerobic suspended growth variations 8, 14 Aerobic attached grov.
Ncurl one-half of the present de! OOO 0. EPA o bflow data unknown. Table Number of U. EPA a. Thus, the basic material presented in thls text is directed toward the design of plants larger than 0.
In the last I0 years. New Directions and Concerns New directions and concerns in wastewater treatment are evidenl in various specific areas of wastewater treatment. The changing nature of the wastewater to be treated. Aging Infrastructure. Some of the problems that have to be addressed in the United States deal with renewal of the aging wa!!
Upgrading and retrofitting treat- ment plants is addressed later in this section. In Lhe former case, extraneou' water has to he collected and treated, and oftentimes may overflow before treatmem. H wllile the standards for treatment have increased significantly, comparatively little or no attf ntion has been focused on the disr.
In the future, however, leaking sewer are ex. Process Analysis and Control. Improved UV disinfection systems are being designed using CfD. Another advamnge is that dynam1c models can be integrated with the process control! Treotment Process Performance and Reliability. Important factors in process selection and design are reatment plant performance and reliability in meeting permit requirements.
Becauoe wastewater treatmt.! On-line monitoring of critical parameters SllCh as total organic carbon TOC , trans- missivity, turbidity, and dissolved oxygen is necessary for building a database and for improving process control.
Chlorine residual monjtoring is useful for do! Two com- ponent. TyptcaJiy, about one-half of the entire plant electricity usagr is for aerati m. Wastewater Disinfection. Capital and operating costs have also been lowered. It is anticipated that the appJkation of UV for treated drinking water and for! The prohlem has become more critical as greater development change! Federal regulations for CSOs are still under drvl"lopment and have not been issued at the time of writing this text 1.
The SSOs may be caused by 1 the entrance of excessive amounts of stonnwater, 2 blockages, or 3 structural, mechanical, or electrical failures. Many overflows result from aging coUection systems that have not received adequate upgrades, maintenance, and repair. The U. EPA has estimated that at least 40, overflows per year occur from sanitary collection systems. The untreated wastewater from these overflows represents threats to public health and the environment. EPA is proposing to clarify and expand permit requirements fur municipal sanitary col- lection systems under the Clean Water Act that will result in reducing the frequency and occurrence of SSOs U.
EPA At the time of writing this text the pro- posed regulations are under review. Pfiesteria is a form of aJgae that is very toxic to fish life. Runoff from pastures and feedlots has been attributed as a potential factor that biggers the effects of these microorganisms. Treatment of Return Flows. The specific treatmem system used will depend on the constituents tha.
The control of odors and in paJticu- lar the control of hydrogen o. The control of odors ic; of increasing environmental concern u.. In some cases, improved industrial pretrt atment has been employed to eliminate these compounds. Retrofitting and Upgrading Wastewater Treatment Plants.
Large numbers of wastewater treatment plants were constructed in the United States. Much of the equipment, now over 20 years old, is reaching the end of its useful life and will need to be replaced.
Process changes to improve performance, meet stricter permit requirements, and increase capacity will also be needed. Fewer completely new treatment plants will be constructed. During this period, the U.
The design capacity of plants providing greater than secondary treatment is expected to increase by 40 pen. EPA, I Some of the innovative treatment methods being utilized in new and upgraded treatment facilities include vortt:x separators, high rate cJarification, membrane biore- actors, pressure-driven membrane filtration ultrafiltration and reverse osmosis-see Fig.
Some of the new technologies, espe- cially those developed in europe, are more compact and are partkularly welJ suited for plants where available space for expansion is limited. In recent years, numerou! This trend will likely continue. Juated or facil- ities are privati7. Privatization is generally defined as a public-private partnership in which the private partner arrange.
In some cases, the private partner may own the facilities. The rea- sons for privatization, howevl'r, go well beyond the possibility of installing proprietary processes. In the United States, the need for private financing appears to be the princi- pal rationale for privatization; the need to preserve local control appears to be the lead- ing pragmatic rationale against privatization Dreese and Beecher, Petersburg in Florida and Rancho Viejo i.
Current Status Most of the reuse of wastewaTer occur. Therefore, new technologies that offer sjgoificaocly improved levels of treatment or constituent reduction need to be tested and evaJuated. Where indirect potable reuse is considered, risk assessmenc also becomes an impoflam component of a water reuse investigation. Risk assessment is addressed in Chap.
Membranes are most significant develop- ments as new producfs are now available for a number of reatment applications. Mem- branes had been limited previously to desalination, but they are being tested increas- ingly for wastewater applications to produce h1gh-quality treated effluent suitable for reclamation.
Tuble 1- 1l. Other treatment plant rt:' idual!. Landtilb u Solar evaporarion pond Current Statu. The number and capacity of landfills. Alkaline stabiliL. With improved treatment methods, higher levels of treatment must be provided not only for conventional wastewater constiruents but also for the removal of specjfic compounds such as nutrients and heavy metal!
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