Geotextile filtration performance for lagoon sludges and liquid animal manures dewatering.

摘要

The maintenance and control of liquid levels in anaerobic lagoons and storage ponds is enhanced by pretreatment with liquid-solid separation or periodic removal of accumulated sludges. Until local disposal or nutrient recycling options become available, sludges can be contained, dewatered, and stored using geotextile filtration. A geotextile filtration testing method termed a hanging-bag test was used to treat dairy lagoon sludge, swine lagoon sludge, liquid dairy manure, and liquid swine manure. Hanging-bag performance was evaluated by: (1) determining solids and plant nutrient mass retention efficiencies (MRE); (2) quantifying the overall volume reduction; and (3) characterizing the dewatered manure. After three fill-dewater cycles, geotextile filtration performed similarly for the sludges, retaining an average 87.6% of total solids (TS), 58.4% of total ammoniacal nitrogen (TAN), and 86.7% total phosphorus (TP). Geotextile filtration was also effective in dewatering and concentrating the sludges; by highly concentrating the retained solids, it reduced the total influent sludge volume requiring disposal to less than 18.5%. Despite relatively high MRE values for liquid swine manure (70.2% of TS, 65.1% of TAN, and 75.7% of TP), geotextile filtration was ineffective as a primary liquid-solid separation, with 60.3% of the total influent volume remaining. For liquid dairy manure (TS=0.71%), geotextile filtration reduced the total influent volume to less than 1%, concentrated the solids and nutrients in the dewatered material 16 to 21 times greater than the influent, and retained 38.4% of TS, 25.8% of TAN, and 45.0% of TP, making this an effective liquid-solid separation technique.