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Topic: Activated sludge

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	Activated Sludge – Treatment, Process Design, Control and Troubleshooting
		The course places appropriate stress on the fundamentals of activated sludge, deals with biological process including microbial activity.
		It covers design criteria and includes a discussion on operation of an activated sludge wastewater treatment plant.
		To provide comprehensive understanding of sludge treatment process, its operation and tests for its effectiveness.
	www.epic-edu.com /epic/products/seminar/may2007/97-0233-1780.htm (1077 words)

	Activated sludge - Wikipedia, the free encyclopedia
		Activated sludge is a process in sewage treatment in which air or oxygen is forced into sewage liquor to develop a biological floc which reduces the organic content of the sewage.
		In all activated sludge plants, once the sewage has received sufficient treatment, excess mixed liquor is discharged into settling tanks and the supernatant is run off to undergo further treatment before discharge.
		Part of the settled material, the sludge, is returned to the head of the aeration system to re-seed the new sewage entering the tank.
	en.wikipedia.org /wiki/Activated_sludge (647 words)

	Sludge - Wikipedia, the free encyclopedia
		Sludge is a generic term for solids separated from suspension in a liquid by a variety of processes.
		In an Imhoff tank, fresh sludge is passed through a slot to the lower story or digestion chamber where decomposition by anaerobic bacteria takes place resulting in liquefaction and a reduction in the volume of the sludge.
		Alternately, the fresh sludge may be continuously extracted from the tank by mechanical means and passed on to separate sludge digestion tanks which operate at higher temperatures than the lower story of the Imhoff tank and as a result digest much more rapidly and efficiently.
	en.wikipedia.org /wiki/Sludge (368 words)

	Activated Sludge
		The preponderance of bacteria living in activated sludge are facultative—able to live in either the presence or absence of oxygen, an important factor in the survival of activated sludge when dissolved oxygen concentrations are low or perhaps approaching depletion.
		Activated sludge flocs, agglomerations of particles that may reach sizes of more than 1mm, are composed of the biological component discussed in the previous section and a nonbiological component.
		The nonbiological component of activated sludge flocs are organic and inorganic particles and extracellular microbial polymers that are generally made up largely of carbohydrates (polysaccharide [complex carbohydrate] and glycoprotein [a conjugated protein in which the nonprotein group is a carbohydrate] fibers).
	www.college.ucla.edu /webproject/micro7/studentprojects7/Rader/asludge2.htm (2726 words)

	Activated sludge wastewater treatment system and method
		Activated sludge is also introduced into the aeration tank 22, with the source of activated sludge being from a recirculation of activated sludge produced during the waste treatment process; accordingly, the activated sludge introduced into the aeration tank 22 would generally be referred to as return activated sludge.
		The amount of activated sludge which is required to resupply the aeration tank 22 (the return activated sludge) flows into the aeration tank 22.
		The rest of the activated sludge (the waste activated sludge) which is removed from the solid/liquid separator 30 is placed in a solids processing location 34, from which it will be dewatered and disposed of.
	www.coursework.info /i/22824.html (2016 words)

	Method for processing activated sludge into useful products - Patent 4119495
		C., the activated sludge being rendered harmless because of the death of pathogenic and toxicogenic organisms and the formation of water-soluble protein, carbohydrate and mineral substances and vitamins.
		The second stream of the suspension of the activated sludge from the distribution device 4 is directed to the vessel 6 wherein alkaline extraction of said activated sludge is conducted at a pH of 9 to 13 and a temperature of 80.degree.
		A suspension concentrated in the device 2 of activated sludge produced in biological purification of domestic effluents and containing 5 percent by weight of dry substances, in an amount of 40 l is transferred to the distribution device 4 wherein the suspension is divided in two parts.
	www.freepatentsonline.com /4119495.html (4870 words)

	THE ACTIVATED SLUDGE PROCESS (Site not responding. Last check: )
		Activated sludge plants can be found in different climate conditions - from the tropics to the polar regions, from sea level(wastewater treatment plants in ships) to extreme elevations(mountainous hotels).
		The invention of the activated sludge process is connected with the efforts of British and American engineers at the end of the last century to intensify biological purification in fixed-film systems.
		The suspension, known as activated sludge was in fact an active biomass responsible for the improvement of treatment efficiency and process intensity.
	ewr.cee.vt.edu /environmental/teach/gwprimer/group12 (260 words)

	[No title]
		Activated Sludge: Sludge particles produced in raw or settled wastewater (primary effluent) by the growth of organisms (including zoogleal bacteria) in aeration tanks in the presence of dissolved oxygen.
		Activated sludge is different from primary sludge in that the sludge particles contain many living organisms that can feed on the incoming wastewater.
		Waste Activated Sludge is typically taken from the settled sludge at the bottom of the Secondary Clarifiers.
	www.cityofbatavia.net /Depts/PubWorks/wwtp/terms.html (1654 words)

	ACTIVATED SLUDGE - MICROBIOLOGY AND PROCESS CONTROL
		Activated sludge consists of a mixed community of microorganisms that metabolize and transform organic and inorganic substances into environmentally acceptable forms.
		The typical microbiology of activated sludge consists of approximately 95% bacteria and 5% higher organisms (protozoa, rotifers, and higher forms of invertebrates).
		The term "activated sludge" refers to a biological process.
	www.dnr.state.wi.us /org/water/wm/ww/tech/asludge.htm (93 words)

	Everything you ever wanted to know about Activated Sludge - activatedsludge.info (Site not responding. Last check: )
		It is a modification of the conventional activated sludge process and operates in the endogenous phase of growth, in which there is not enough food remaining in the system to support all of the microorganisms present.
		An activated sludge process designed to remove nitrogen and phosphorus biologically, the process optimizes P removal efficiency at the expense of N removal efficiency by introducing a small return sludge denitrification zone as part of the process train.
		Sludge is recycled from the clarifier to anoxic 1 (return sludge or 's' recycle), a recycle from anoxic 1 to the anaerobic zone ('r'-recycle) and a mixed liquor denitrification recycle from the aerobic zone to anoxic 2 ('a'-recycle).
	www.activatedsludge.info /resources/glossary.asp (16261 words)

	Pipeline Spring 2003
		Activated sludge process plants are good choices too for isolated facilities, such as hospitals or hotels, cluster situations, subdivisions, and small communities.
		By analyzing the different characteristics of the activated sludge or the sludge quality, plant operators are able to monitor how effective the treatment plant’s process is. Efficient operation is ensured by keeping accurate, up-to-date records; routinely evaluating operating and laboratory data; and troubleshooting, to solve problems before they become serious.
		Activated sludge consists of a mixed community of microorganisms, approximately 95 percent bacteria and 5 percent higher organisms (protozoa, rotifers, and higher forms of invertebrates).
	www.nesc.wvu.edu /nsfc/Articles/PL/PL_sp03_web/pl_sp03_ActSldgPrcss.htm (1849 words)

	Activated Sludge (Site not responding. Last check: )
		The sludge from the final clarifiers is mostly returned to the aeration tanks.
		The sludge is then pumped into a second sludge holding tank (recall that there was one holding tank for just primary sludge).
		The sludge level in the primary tank is controlled to keep a constant 3 foot blanket.
	www.rpi.edu /dept/chem-eng/Biotech-Environ/Guilderland/activsludge.html (132 words)

	Activated Sludge Bulking (Site not responding. Last check: )
		Activated sludge bulking, statistical analyses, non-mechanistic modelling, expert systems.
		It is estimated that bulking was a problem prevalent in half the activated sludge plants world-wide (Tomlinson, 1979).
		Despite the vast literature available on the causes and control of activated sludge bulking, poor settleability is still estimated to be one of the major operational problems in full-scales treatment plants installed world-wide (Tomlinson, 1982; Wanner, 1994).
	www.engr.uconn.edu /~faisal/research/bulk_doc.html (837 words)

	Stevens Point Waste Water Department - Waste Water Treatment Process
		In the activated sludge process, microorganisms are mixed thoroughly with organic material in the wastewater so that the microorganisms grow by using the organics as food.
		The wastewater flows continuously into the aeration tanks where air is injected to mix the activated sludge with the wastewater forming "mixed liquor" and to supply the oxygen needed for the microbes to break down the organics.
		Most of the settled sludge is returned to the aeration tank to maintain a high population of microbes to permit rapid breakdown of the organic material.
	www.stevenspointwaterdpt.org /Waste/process.html (1411 words)

	ACTIVATED SLUDGE POPULATION DYNAMICS AND
		The paper is aimed at three main topics of population dynamics, i.e., competition of nitrifying and organotrophic bacteria, population dynamics of enhanced biological phosphate removal, and activated sludge bulking and foaming.
		The examples were selected from a large national survey of activated sludge plants accomplished in 1995-1999.
		Traditional activated sludge separation problem of bulking was observed with much less frequency than expected.
	www.vscht.cz /tvp/abstracts/wanner_00_1.htm (258 words)

	Improving treatability of activated Sludge - Water and Wastewater.com Help Forum
		Having experienced problems trying to thermally dry activated sludge we are looking to apply any pre-treatment to the activated that would break up its cellular structure and hence release intercellular water.
		Ultimately our aim is to make the subsequent sludge cake produced from the activated sludge more easy to mix and bind in with dried sludge granules as part of the subsequent thermal drying process.
		Using ultrasound for enhanced sludge digestion relies on inducing cavitation in the liquid to produce lysis of the cellular sludge material, thereby increasing the availability of the organic material to bacteria in anaerobic digesters.
	www.waterandwastewater.com /cgi-bin/yabb/YaBB.pl?board=general&action=display&num=1108652960 (959 words)

	Pulp & Paper: Improved control makes activated sludge treatment more viable
		In the paper industry, the commonly perceived drawback of activated sludge systems-namely the control of nutrients (phosphorus and nitrogen)-can actually be handled so efficiently that the effluent to the receiving stream contains lower concentrations of the nutrients than what is typically found in the influent.
		The planning and construction of activated sludge plants has not been without problems either, especially since there are some economic restrictions within which mills need to operate.A good example of this is all the activated sludge plants that were built during a short time period in Finland in the 1980s.
		From an operational point of view, the most critical parts of the activated sludge plant are primary sedimentation, the aerators and their location, assurance of power to the compressors, spare compressors, and sludge dewatering.
	www.findarticles.com /p/articles/mi_qa3636/is_199811/ai_n8824273 (1477 words)

	ES&T Online News: Recycling sludge bacteria magnetically
		By replacing the gravitational settling that is commonly used in activated sludge treatment with magnetic separation, the new process could make wastewater treatment more efficient.
		Activated sludge treatment relies on countless legions of “active” bacteria to digest the organic matter in sludge, and it is used throughout the world for wastewater purification.
		One of the problems that plague activated sludge treatment occurs when long strands of filamentous bacteria form mats between the bacterial balls, preventing the flocs from settling.
	pubs.acs.org /subscribe/journals/esthag-w/2003/may/tech/rr_sludge.html (602 words)

	The Microbiology of Activated Sludge
		Activated sludge can be defined as "a mixture of microorganisms which contact and digest bio-degradable materials (food) from wastewater."
		Return to Activated Sludge: Microbiology and Process Control.
		Beggiatoa spp is only one filamentous bacterium found in activated sludge that is motile.
	www.dnr.state.wi.us /org/water/wm/ww/tech/biol.htm (2284 words)

	Textile Research Journal: Reuse of Activated Sludge Biomass: Equilibrium Studies for the Absorption of Basic Dyes on ...
		In a biological treatment system, such as activated sludge processes, a sludge volume of 25-50% of the flow through the plant is drawn off from the settling tank, and between 50 and 90% of this must return to the aeration zone [20], depending on the desired mixed-liquor suspended solids.
		The sludge was dried in an oven at 115°C [4] for 20 hours, ground with a mortar and pestle, sieved into a discrete particle size range (150-300 µm or other), then stored in a desiccator at room temperature until used.
		The reason for this is that this activated sludge comprises a complex and diverse microbial community made of bacteria, fungi, protozoa, and rotifiers [6].
	www.findarticles.com /p/articles/mi_qa4025/is_200408/ai_n9421154 (1339 words)

	NAMS 2004: Program
		In this study, three types of activated carbon were compared for their effects on membrane filtration of an activated sludge: powdered activated carbon (PAC), granular activated carbon (GAC) and powdered activated carbon saturated with adsorbed EPS (SPAC).
		Filtration experiments were conducted by filtering an activated sludge treating municipal wastewater at a constant transmembrane pressure of 10 psi through flat-sheet cellulose ester membranes in a 200 ml complete-mix cell.
		Activated sludge without activated carbon had a filtration resistance (in x1012/m) of 6.4, as compared to 5.0 for the activated sludge dosed with PAC.
	www.che.utoledo.edu /nams/2004/viewpaper.cfm?ID=712 (555 words)

	Strathkelvin Instruments Limited (Site not responding. Last check: )
		Our instrumentation can quickly and directly measure Activated Sludge bacterial performance saving our clients time and money by determining the effects of reducing feeding and aeration programmes, and the inhibition of the bacteria whilst also increasing the loading of their plant.
		In order to monitor the 'health' of the activated sludge bacteria, as an indication of the efficiency of biodegradation, daily measurements are made of the respiration rates of samples from the aeration tanks.
		Samples of activated sludge, in endogenous state or at maximum respiration rate, with or without allyl thiourea addition (according to the objectives of the test), are placed in the respiration tubes.
	www.environmental-expert.com /technology/strathkelvin/strathkelvin.htm (1563 words)

	Activated Sludge Foaming Control (Site not responding. Last check: )
		The principles of dissolved air flotation (DAF) which could potentially be applied to solve activated sludge foaming problems are discussed in the relevant context.
		Modification of existing Activated Sludge Plants(ASP) by incorporating a DAF facility in parallel with the aeration basin conceptually indicates much promise as an alternative solution to foaming problems.
		Therefore, if the principles of DAF could be applied, in the relevant context of activated sludge foaming, it may be possible to separate foaming organisms from the activated sludge very rapidly by enhancing the selective flotation of these organisms.
	www.engr.uconn.edu /~faisal/research/daf.html (919 words)

	Activated Sludge (Site not responding. Last check: )
		Activated sludge uses microorganisms to break down dilute aqueous organic contaminants into less toxic compounds.
		The waste stream is sent to a clarifier for sludge removal (and partial recycle).
		The Activated Sludge process is generally effective for aqueous wastes where concentrations are less than 1%.
	tristate.apogee.net /et/ewtwasg.asp (116 words)

	Practical Control Methods For Activated Sludge Bulking and Foaming
		Type 1701 bulking has occurred in an oxygen activated sludge plant operated at high F/M at a DO concentration of 12-14 mg/L, which was cured by raising the DO to 20 mg/L. As a rule, always trust the microscopic observation of low DO filaments to indicate oxygen limitation rather than the aeration basin DO values.
		The goal of chlorination is to expose the activated sludge to sufficient chlorine to damage filaments extending from the floc surface while leaving organisms within the floc largely untouched.
		Microscopic examination of the activated sludge during chlorination is recommended to control chlorine application.
	www.dec.state.ny.us /website/dow/bwcp/ta_sludbulk.html (2898 words)

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