Introduction: Is it Art, Science or Both 
Treatment plants must remain flexible in handling changes that occur from time to time and as they say 
"it all rolls downhill". Changes with flow, retention times, weather, upstream process changes, chemical additions all can seem like a challenge, cause frustration, and provide non-desired results, if the proper pre-treatment steps are not considered for sludge dewatering. In addition consistency of process, polymer selection, proper maintenance, and operator knowledge, are all factors to be considered when implementing mechanical dewatering equipment. If not properly managed, low cake solids will lead to not only frustration, but also higher cost for polymer, operation, and disposal. Poor filtrate quality can lead to a waste in time and process by sending unneeded solids back to the headworks, double processing, and increased cost of polymer, as well. 
Understanding pretreatment and the impact on dewatering is very important to a successful outcome. There are multiple ways to pretreat sludge before it enters the dewatering process, and it will be different for each facility. Sludge conditioning options are various, sometimes rather simple, and other times more complex if there is pretreatment, and knowledge of the process will assist in mitigating any headaches or costs. Environmental/weather conditions will impact outputs as sludge temperature and water temperatures impact dewatering by changing the characteristics of the sludge and polymer. Any change in upstream inputs can also change conditioning requirements, resulting in the use of too much or too little sludge, both causing financial impacts. Dialing in mechanical dewatering equipment will also allow for superior sludge processing. Proper maintenance of equipment and effective operator training are the final two considerations that with upkeep, both provide a good dewatering experience. 
Being able to dial in all factors for mechanical dewatering equipment will allow for superior sludge processing. Innovative dewatering equipment, knowledge, and industry partners can allow facilities to maximize their dewatering capabilities, reducing wasted time, money, and resources, and resulting in higher cake solids and a better filtrate quality.