A simple method to equalize the workload when operating several small wastewater treatment plants: a case study

Abstract

The aim of the present study is to define a simple (and easy to use) method to equalize the workload of personnel operating several small wastewater treatment plants (SWWTPs). The approach is illustrated through a case study which is the result of collaboration between researchers and a water and wastewater management company operating in Southern Italy. The topic is important since personnel have a significant impact on the operating costs of SWWTPs, and the approach outlined results in the minimum number of staff being required to assure the management of the service. Four kinds of work units are considered: plant managers, assistant plant managers, laboratory technicians and executives. In order to develop a practical, feasible and easy to use method, the workload was evaluated considering only the population equivalent (PE) and the number of plants managed. The core of the method is the evaluation of the percentage of time that the personnel units devote to the operation of SWWTPs of the municipality considered. The proposed procedure offers a useful tool to equalize the workload, both in terms of PE and the number of plants managed, the procedure being easily modifiable to introduce other evaluation criteria. By using familiar concepts such as PE and number of plants managed, the approach of the method can easily be understood by management. It can also be readily adapted to other similar situations. IntroductionDespite the importance of cost efficiency in wastewater treatment, to the best of our knowledge there have been few studies of this topic reported in the literature. Possible factors are difficulties in obtaining the required information and the shortage of researchers carrying out economic analysis of treatment processes [1].Managing wastewater treatment plants involves both operational and maintenance costs (O&M). The operational costs include personnel, energy (typically, electrical energy), fuel, chemicals and sludge disposal. Maintenance costs are usually divided into ordinary maintenance (cleaning of premises, grass and vegetation cutting, machinery greasing, periodic painting, etc.) and extraordinary maintenance costs (replacement of machinery or parts, fundamental interventions in areas of the plant, general reconstruction of masonry structures, etc.) [2][3][4].From a monetary point of view, the O&M costs are not related to the value of the investment involved (design and construction). However, considered from a technical point of view it becomes clear that operating costs are determined almost entirely by the type of plant and equipment used. Consequently, careful consideration must be given

Validated predictive modelling of the environmental resistome

“…Assumption 1: The size of the WWTP will be reflected by the population equivalent. Population equivalent has previously been used as the standard method for inferring the size of a WWTP ( P ) ( De Feo et al , 2013 ).…”

Task Scheduling–Review of Algorithms and Analysis of Potential Use in a Biological Wastewater Treatment Plant

“…Research papers [5,20,25,54,58] deal with flow shop problems. Papes [ 10,11,18,61,62,45] concern problems related to human resource management and scheduling of work teams. On the other hand, papers [12,16,19,21,22,26,29,30,31,33,34,51,57] concern task scheduling problems in cloud computing.…”

“…The paper [62] deals with the balanced workload of personnel operating several wastewater treatment plants. The scheduling problem is defined as the distribution of annual working time of four types of work units: Manager, Assistant, Laboratory, Executive in a certain number of facilities.…”