Articles
COMPOSTING OF SEWAGE SLUDGE AND STRAW: LABORATORY SCALE SIMULATION AND EVALUATION OF SELECTED TEMPERATURES AND EFFECT ON COMPOSTING PERFORMANCE
Article number
302_11
Pages
113 – 124
Language
Abstract
Controlled static aerated pile composting via temperature feedback control enables the optimisation of microbial activity within a composting mass at a selected maximum temperature, by evaporative removal of heat with variable aeration.
A study was carried out to evaluate the losses from compostng a mixture of sewage sludge and straw (10:1 w/w) at selected temperatures between 30 and 65 degrees centigrade in a bench scale composting simulator, for two separate batches, series A and series B. Aeration flow rate was set at 1600 cc/min and operated as a periodic timer function until the maximum temperature set point (MTSP) of each run was achieved, where aeration became a function of temperature feedback control.
All runs except 30 and 35 in Series A and 30 in series B were controlled within 0.5°C of the MTSP. The duration of maximum temperature over the ten days composting of each run was found to decrease with increasing maximum temperature set point for all runs in both series A and B. Greater drying of material was achieved in runs below 50°C and maximum dry weight loss was found at 45°C. Oxygen consumption was also maximised in runs at 45°C whereas ammonia volatalisation at this temperature was found to be less than in runs at higher temperatures.
In series B aeration per kilogram moisture lost increased dramatically with decrease in temperature control from 65°–30°C.
A study was carried out to evaluate the losses from compostng a mixture of sewage sludge and straw (10:1 w/w) at selected temperatures between 30 and 65 degrees centigrade in a bench scale composting simulator, for two separate batches, series A and series B. Aeration flow rate was set at 1600 cc/min and operated as a periodic timer function until the maximum temperature set point (MTSP) of each run was achieved, where aeration became a function of temperature feedback control.
All runs except 30 and 35 in Series A and 30 in series B were controlled within 0.5°C of the MTSP. The duration of maximum temperature over the ten days composting of each run was found to decrease with increasing maximum temperature set point for all runs in both series A and B. Greater drying of material was achieved in runs below 50°C and maximum dry weight loss was found at 45°C. Oxygen consumption was also maximised in runs at 45°C whereas ammonia volatalisation at this temperature was found to be less than in runs at higher temperatures.
In series B aeration per kilogram moisture lost increased dramatically with decrease in temperature control from 65°–30°C.
Authors
E. Walter, J.M. Lopez-Real, J. Wharfe
Keywords
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