Environmental Engineering Reference
In-Depth Information
two belts move between a series of rollers, pressure squeezes additional
water out of the solids. The solids are then discharged onto a conveyor
belt for transport to storage or disposal. Performance factors for the belt
press include sludge feed rate, belt speed, belt tension, belt permeability,
chemical dosage, and chemical selection.
Filter presses have lower operation and maintenance costs than
vacuum filters or centrifuges. They typically produce a good-quality
cake and can be batch operated; however, construction and installation
costs are high. Moreover, chemical addition is required, and the presses
must be operated by skilled personnel.
10.7.3.1 Operational Considerations
Most plate and filter press operations are partially or fully auto-
mated. Operation consists of observation, maintenance, and sampling
and testing. Operation of belt filter presses consists of preparation of
conditioning chemicals, chemical feed rate adjustments, sludge feed rate
adjustments, belt alignment, belt speed and belt tension adjustments,
sampling and testing, and maintenance. Common operation problems,
causal factors, and recommended corrective actions for the plate press
and belt filter press are provided below:
•
symptom 1.
Plate press plates fail to seal.
Causal factors:
Poor alignment; inadequate shimming
Corrective actions:
Realign parts; adjust shimming of stay
bosses.
•
symptom 2.
Plate press cake discharge is difficult.
Causal factors:
Inadequate precoat; improper conditioning
Corrective actions:
Increase precoat and feed at 25 to 40
psig; change conditioner type or dosage (use filter leaf test to
determine).
•
symptom 3.
Plate press filter cycle times are excessive.
Causal factors:
Improper conditioning; low feed solids
Corrective actions:
Change chemical dosage; improve thicken-
ing operation.
•
symptom 4.
Plate press filter cake sticks to conveyors.
Causal factor:
Improper conditioning chemical or dosage
Corrective action:
Increase inorganic conditioner dose.
•
symptom 5.
Plate press precoat pressures gradually increase.
Causal factors:
Improper sludge conditioning; improper precoat
feed; plugged filter media; calcium buildup in media
