Chemical rehabilitation of rapid sand filter at Klagshamn WWTP in Malmö / Kemisk rekonditionering av sandfilter på Klagshamn ARV i Malmö

Chemical rehabilitation of rapid sand filter at Klagshamn WWTP in Malmö / Kemisk rekonditionering av sandfilter på Klagshamn ARV i Malmö

At many wastewater treatment plants (WWTPs), rapid sand filters are used as polishing step before the wastewater is released to the recipient. Thus, after time, the media gets clogged and the filters are regularly backwashed. In case of poor backwashing, the next filtration cycle will begin with an inefficient filter. Agglomerates of media grains, flocculation chemicals, biosolids and fats can lead to appearance of “mud balls”. “Mud balls” can grow rapidly and form cracks, increasing the local filtration rates or causing increased head loss and, consequently, destroy the filter. In such cases, rehabilitation of filter media is needed. Replacing the old media is a costly and time consuming procedure. In this paper, different chemical cleaning methods are compared with the aim to find a procedure that can be applied in a full scale without negative impact on the recipient or on the main process. Ten percent solution of sodium hydroxide has shown good impact on media characteristics and can solve problems with “mud balls”. Applied in full scale, the method has four to five time lower cost compared to replacement of the filter media.

Författare Dimitrova, I., Dabrowska, A.
Årgång 2019
Nummer 2
Sida 197-203
Nyckelord Rapid sand filter; chemical rehabilitation; mud balls; costs
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