ABSTRACT
An unconventional cascade control system, for the regulation of air supply in activated sludge wastewater treatment plants (WWTPs), was tested. The dissolved oxygen (DO) set point in the aeration tank was dynamically calculated based on effluent ammonia concentration, following a fuzzy logic based approach. First, simulations were conducted, according to the BSM2 protocol, for a general comparison with more conventional control strategies. It turned out that the effluent quality could be improved by 7-8%, based on the EQI parameter. Moreover, the aeration energy requirement could be reduced up to 13%. Subsequently, the system was installed in a full-scale WWTP. While stably complying with the ammonia effluent standard (10 mg/L), excess air supply was prevented, and a reduction of the specific power consumption (kWh/kgCODremoved) of 40-50% was recorded with respect to the previously installed PID controller (fixed DO set point).
Subject(s)
Fuzzy Logic , Waste Disposal, Fluid , Ammonia , Sewage , WastewaterABSTRACT
Several indicators for the evaluation of the MSW collection systems have been proposed in the literature. These evaluation tools consider only some of the aspects that influence the operational efficiency of the collection service. The aim of this paper is to suggest a set of (easy to calculate) indicators that overcomes this limitation, taking into account both the characteristics of collected waste and the operational - economic performance. The main components of the collection system (labour, vehicles and containers) are separately considered so that it is possible to quantify and compare their role within the whole process. As an example of application, the proposed approach was used for comparing the MSW collection strategies adopted in four towns in Northern Italy. Results are discussed and a comparison with alternative assessment methods available in the scientific literature is reported.
