Caracterização dos lodos produzidos na ETE Cabanga - Recife - Pernambuco.

Abstract

This research was carried out at Cabanga Sewage Treatment Plant, Recife-Pernambuco state (8o 10' 52" S, 34° 54' 0" O, 2m a.s.l.), belonging to COMPESA (Companhia Pernambucana de Saneamento). After preliminary treatment, raw sewage was conducted to primary settling tanks and raw sludge was treated in anaerobic digesters. The final sludge was unloaded into drying beds and dewatered through evaporation and drainage. This work aimed the characterization of (a) raw sludge from primary settling tanks; (b) digested sludge from anaerobic digesters; (c) dried sludge, after several drying periods and (d) draíned liquid. From March to October 1993 samples were taken at regular intervals and analysed for temperature, pH, total, fixed and volatile solids, specific weight, humidity, total nitrogen, ammonia, total phosphorus, salinity and helminth eggs. Results showed a drained liquid and raw and digested sludge with high leveis of salinity due to presence of sea water in the sewerage collecting system. Ti de movement promoted in raw sludge a wide variation of chloride and sodium concentration (7005 - 14244 mg/l and 5137 - 8318 mg/l respectively). During dewatering of digested sludge, chloride and sodium concentration were also high, varying from 4200 - 12175 mg/l and 3067 - 15330 mg/l respectively. Draíned liquid presented of values varying from 4118 to 10880 mg/l for chloride and from 2277 - 11270 mg/l for sodium. Helminth eggs counts were high in raw and digested sludge Ascaris lumbricoides varied in the former from 8600 - 45467 eggs/1 and within the range 15378 - 37422 eggs/1 in the latter. For Trichuris trichiura this variation comprised values from 533 to 1667 eggs/1 and 133 - 1267 eggs/1 respectively. Dried sludge high salinity and helminth eggs contents restricted tts agricultural use once they would cause soil and píant damage and environmental contamination.