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Ask the Wastewater Expert

Daniel L. Theobald

Known in the industry as “Wastewater Dan,” Daniel L. Theobald, proprietor of Environmental Services, is a professional wastewater and safety consultant/trainer. He has more than 24 years of hands-on industry experience operating many variants of wastewater treatment processing units and is eager to share with others his knowledge about water conservation (

How sludge settles is a key performance indicator

Someone recently asked, 'What are some procedures for measuring settle-ability of activated sludge?'
Collecting samples, use of equipment for simulating settle-ability and the interpretation of results are all part of measuring activated-sludge settle-ability.
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For a firm grasp of trends, monitor wastewater treatment ‘look and feel’

Someone asks, 'What are the parameters relevant to visual and olfactory observation of activated sludge?'
Activated sludge is a biological wastewater treatment that speeds waste decomposition. It is added to wastewater and the mixture, referred to as “mixed liquor,” is aerated and agitated. Subsequently held in a tank, the mixture settles out by sedimentation and is disposed of, i.e., as they say, “wasted,” or returned to the aeration tank as needed. The remaining wastewater then undergoes further treatment.
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Getting back to basics: What is pH?

The most used measure in wastewater treatment, and for good reasons
The “potential of hydrogen” or “pH” is the measure of free hydrogen activity in water and thereby indicative of the measure of its free acidity or free alkalinity. Gauged on a numeric scale of 0-14, solutions with a pH of less than 7.0 are acids. Solutions with a pH greater than 7.0 are bases and solutions with a pH of 7.0 are neutral.
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Batch and continuous pH control compared and contrasted

Someone recently asked, “What are process controls for adjusting and maintaining pH during wastewater treatment?”
The pH is one of the most important and frequently used measurements in wastewater treatment. Dependence of pH occurs in practically every phase of water supply and wastewater treatment, e.g., acid-base neutralization, water softening, precipitation, coagulation, disinfection and corrosion control.
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What are operational process controls for overall effective sludge dewatering?

How sludge gets dry
Press filtration using plates or belts and centrifugation separation are common methods for dewatering sludge. Someone recently asked, “What are operational process controls for overall effective sludge dewatering?”
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What are process controls for dissolved oxygen during biological treatment?

Dissolved-oxygen effluent at the secondary clarifier is primarily affected by the dissolved-oxygen control processes during the activated-sludge process.
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What are the parameters of an extended-aeration activated-sludge system?

Even when regular wasting is carried out, a high degree of flow deviation in extended aeration plants will cause loss of solids.
he activated sludge process is the most widely used biological water and wastewater treatment. As is well known, by its means, suspended-growth microorganisms are applied to breakdown wastes. Aeration, the mixing of air and a liquid, is the means used to speed the reactions involved.
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What are the treatment options for landfill leachate?

New contributor to Water/Waste Processing aims to answer readers’ most pressing questions
It’s said the United States has 1,654 landfills, handling more than 250-million tons of trash each year.
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