TROUBLE SHOOTING
TROUBLE SHOOTING FILTER PRESS PROBLEMS
Below we have listed some of the most common trouble spots in filter pressing, and have given a few hints in producing a consistently dense filter cake. It is important to remember that the most critical factor in pressing, and in water treatment in general is the quality and nature of the waste stream entering the system. For this report we will assume the press is operating properly.
WET SLUDGE CAKE
1) Lack of sufficient blowdown time, or improper placement of blowdown valves. 2) Oil or grease has blinded the press cloth. Needs to be cleaned and air dried. 3) Oil and grease needs to be coagulated and de-emulsified prior to pressing. 4) Hydroxide sludge has blinded the press cloth. Acid wash and rinse well. 5) Overdosing of DTC or other coagulants such as alum, which can blind a press. 6) Some aluminum solutions such as etchants are too dense to be pressed properly. 7) Starting the pump pressure too high at beginning of cycle; can blind press. 8) Insufficient pump pressure at end of cycle. 9) Opening press before pump cycle ends.
FILTER PRESS AIDS - PRE-COATS
There are a number of good filter aids on the market today. These can be purchased from many suppliers.
DE…….. Diatomaceous Earth for pre-coating or body feeding. Purlite…. Filter aid similar to DE; many grades available & non-hazardous. Carbon… Works to remove organics in wastewater, used with pre-coats.
FILTER PRESS AIDS - CHEMICALS
Magnesium Hydroxide Creates a more dense and dry cake. Can be used as a primary precipitant for metals, neutralizer, or as a body fill for added surface area.
Poly-Alum (PAC) A family of coagulants which help create large flocs that press well.
De-Tackifiers A family of chemicals used to coagulate photo resist, paints to aid in pressing.
Polymers A wide range of compounds to increase the mass and hence the fall-out rate of suspended waste particles.