Fine Screens

Main fine screen types are; static sieve screen, drum screen, micro screen etc.

Fine screens water level is measured at both sides of the screen by level meter (LE) sensor. Then electrical signal is sent to the transmitter (LT) in which the signal will convey the form that controller (LC) can understand. In the controller, the range for the head loss is entered.

Therefore, when that range will be exceeded, the controller makes the motor (M) of screen run and cleaning procedure starts automatically. For warning purposes, there is an alarm (LAH) on the panel mounted instrument that will inform the operator about the high head loss.

There is no automation difference in fine screens, since; they are also mechanical screens.

Wastewater Sludge

What is Sludge in Environmental Engineering?

Sludge is a semi-solid substance formed during water and wastewater treatment that is removed by settlement. It is a substance that requires further treatment; unless this is done it may pose harm to the environment and public health.

Why further treatment is needed for sludge?
Because sludge includes; large amounts of organic matter, nurients, pathogenic microorganism, huge amount of water.

Sludge production amounts
In order to calculate the amounf of sludge produced in a conventional domestic wastewater treatment plant, dry solid matter content is assumed as roughly 0.09 kg per capita per day in wastewater treatment. For instance, for a residential area with 1.000.000 population, 90-100 tons sludge production can be expected in a day.

Sludge	Conc.of Solids (%)	Characteristics
Raw Primary	4-8	Bad odor, gray-brown color, does not drain well on drying beds, can be dewatered mechanically
Anaerobic Primary Digested	6-10	Black color, produces gas, dewaters well on drying beds
Wasted Activated Sludge	0.5-1.5	Little or no odor, yellow-brown color, flufly, biologically active, difficult to dewater
Mixed Digested (Primary and Waste Activated)	2-4	Black-brown color, produces gas, not as easy to dewater as digested primary
Aerobic Digested	1-3	Yellow-brown color, biologically active, generally difficult to dewater
Waste Alum	0.5-1.5	Grey-yellow in color, odorless, very difficult to dewater