Aim of work:
The studied Municipal Wastewater Treatment Plant which is located in Biskupiec, Warmian-Masurian voivodship, Poland. It serves Biskupiec city and Rukławki village. Inlet wastewater consists of household, industrial sewage from nearby meat plants and rainwater. The average capacity is 1,450 m3/d, with a maximum of 1,725 m3/d.
After mechanical and biological treatment, an excess sludge with humidity of approximately 99.7 – 99.8% is generated in an amount of approximately 360 m3/d, which is then gravitationally thickened to a dry solids content of 1.0 – 2.0% in an amount of approximately 60 – 120 m3/d. Earlier, the sludge was dewatered on the belt filter press and then utilized partially for agriculture needs as well as distributed to the sludge plots.
The necessity of reconstruction was caused by poor dewatering process efficiency which affected in the high humidity of dewatered cake (approx. 10 %). Additionally, the existing belt filter press capacity of approx. 60 m3/d was insufficient to process the entire amount of sludge even beside the fact it was operating with high accident rate.
As a company with a rich experience in municipal sludge dewatering technology, EKOTON Industrial Group was able to offer an appropriate solution and was accepted to work on this project.
Progress of work:
To get acquainted with the case, laboratory and pilot studies were carried out. First of all, flocculation tests were conducted and the optimal process parameters were obtained. Further pilot scale tests allowed them to find the optimal dewatering process parameters in real conditions. The results were analyzed and necessary calculations were done which gave EKOTON constructors the opportunity to fit and design the best appropriate dewatering technology.
After the old dewatering complex was removed the new equipment was installed with respect to all the client and labuor protection requirements. Then it was commissioned and all technological parameters were adjusted to meet the best dewatering efficiency for this kind of sludge.
|Average WWTP capacity||1450 m3/d|
|Sludge dewatering facility capacity||120-150 m3/d or 1,9 tDS/d (135 kgDS/h)|
|Average DS content in sludge||1,5 %|
|Average DS content in dewatered cake||15-17 %|
|TSS in filtrate||60-260 mg/l|
|Flocculant dosage||9,3 kg/tDS|
|Manual control time (for 8 h working shift)||20 min on adjustment + 30 min on overall maintenance (can be carried out during nonstop equipment operation)|
|Availability (as a metric of overall equipment efficiency)||90-97%|
The reconstruction of the sludge dewatering facility at the Municipal Wastewater Treatment Plant in Biskupiec allowed IT to increase its capacity from 60 to 120-150 m3/d.
Despite an extremely low dry solid content in initial sludge (caused by its specific composition and poor thickening process efficiency) the installed equipment managed to obtain dewatered cake of a transportable consistence and this allowed a save on the expenses of further transportation and utilization due to its quantity reduction. The new technology allows obtaining a higher dry solids content in cake (up to 17%) and cleaner filtrate (60-260 mgTSS/l) with fully automatic and reliable operation of the EKOTON equipment, even in such a complicated case when the average dry solids content in the inlet sludge is only 1,5%.
Moreover, implemented technology leads to additional operating costs decreasing due to water, electricity and reagent consumption reduction.