Marek Romuald Rynkiewicz, Marta Kisielewska
Uniwersytet Warmińsko-Mazurski, Olsztyn

Impurities which are produced in the process of intensive fish breeding usually accumulate at the bottom of ponds and pools where the fattening is conducted, resulting in sludge rich in organic matter and biogenic elements. The sludge, consisting mainly of fish faeces and the fodder uneaten by the fish, accumulates in special zones intended for this purpose. As the experiment shows, the ability of the sludge to yield water is very poor and the sludge should be classed as poorly dewatering. Therefore, before it was dewatered in a laboratory the sludge was conditioned with inorganic compounds and cationic polyelectrolytes in order to facilitate the process. The inorganic compounds used for conditioning were: technical grade iron (III) sulphate – trade name “PIX 113”, aluminum sulphate and calcium oxide. The sludge was dewatered in a reduced pressure device, equipped with a Büchner funnel, which enables the determination of the specific resistance. The collected sludge contained variable amounts of dry matter and organic matter. The study presents the results of determination of the specific resistance, final dewatering of sludge and its content of organic matter, depending on the type and amount of the conditioning agent applied. The results also allowed the determination of the doses which optimally facilitate the dewatering process and reduce the degree of sludge hydration. The process effectiveness was found to be dependent mainly on organic matter content in sludge. It was also found that the specific resistance was most reduced by cationic polyelectrolytes, while the final hydration was the lowest when calcium oxide was used. The determined optimal doses depended on organic matter content and ranged: for iron sulphate from 0.7 to 15% (d.m.), for aluminum sulphate from 0.6 to 15% (d.m.), for calcium oxide from 7 to 30% (d.m.), for cationic polyelectrolytes from 0.064 to 0.19% (d.m.) of sludge. No statistically significant differences were found in dewatering effectiveness between iron sulphate and aluminium sulphate.

Słowa kluczowe
odwadnianie osadów; gospodarstwa rybackie

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