PROJECT DESCRIPTION
BACKGROUND
The use of the sea for the disposal of sewerage effluents from coastal communities has been a world-wide practice for centuries. Increasing pressure has, however, been exerted on the assimilative capacities of receiving waters to self purify and disperse an ever growing pollution load from expanding population. There is currently an absence of reliable and economic methodologies for monitoring sea outfalls. With the need to control the effect of the discharge of waste water in water bodies more carefully, the availability of a simple and reliable system for the monitoring of the outfalls and henceforth to safeguard the environment of coastal communities has become evident. While the environmental effects of outfalls have been studied with costly monitoring campaigns, very little has been done in the area of monitoring the outfall performance, in terms of the synergy with the operation of the WWTP and overall efficiency. Most of what is available in the field of the diffuser “operational behaviour” remains at a theoretical stage. The scarceness of verification in the field of the available theoretical models and the present lack of a technique for the verification in real time of the functioning does not permit to formulate Guidelines for a more efficient design and for operating standards.
OBJECTIVES
The AQUARIUS project planned to define and to implement a reliable and transferable monitoring system of the outfalls discharging from Waste Water Treatment Plants (WWTP), based on techniques of real time acquisition of the parameters characterising the correct functioning of the diffusers and of the interaction between discharged waters and the receiving water bodies, with the use of underwater sensors and of acoustical underwater transmission technologies. The project would demonstrate, through model tests and the realisation of a prototype installed on an existing outfall - WWTP of Sturla, Genova - the applicability and reproducibility of a standard operating and environmental control system. At the end of the project the system would be integrated in the WWTP SCADA. To reach the objectives, the project would have to do the following: • definition of the control and monitoring system of the correct functioning of the diffuser through measures of flow rate/pressure or equivalent or the assessment of the operating functionality of the diffuser; • definition of the system for the monitoring of the jet velocity for the evaluation of the primary dilution as index of the diffuser's efficiency; • definition of the functionality of the acoustic data transmission systems for the verification of the correct operation of the diffuser through the WWTP SCADA; • verification through periodical environmental monitoring campaigns of the impact of the discharge on the most significant parameters characterising the marine environment around the diffuser, to evaluate eventual correlation of such data to the discharge parameters.
RESULTS
The project achieved the following results: - development of a tool for a better knowledge of the synergy between the depuration plant and its discharge conduit; - development of a tool for the field monitoring and control of dilution and diffusion into the marine environment of the effluents from the depuration plant; - development of a basic tool for the control of hydraulic functioning of the underwater diffusers; - possibility of continuous analysis of environmental changes and; - possibility of immediate interventions in case of malfunctioning. The cost/benefit analysis showed that the reproduction cost for the system is around € 100.000. The direct benefits of the system are: - reduction (or re-utilisation for other tasks) of one to two person/year for data collection and analysis; - € 15.000/year savings for underwater inspections by using divers (the saving is even greater if the inspections are carried out by using a ROV); - about € 25.000/year savings for boat and equipment rental for environmental controls (carried out by Ecoturtle in the Aquarius system). The indirect benefits are: - real-time data acquisition with the possibility of immediate analysis and evaluation and immediate detection of malfunctioning (identification of causes and correction interventions); - better monitoring of the environment due to the continuous control of discharges. The project idea could be potentially transferred to other coastal areas with comparable characterisics and/or problems. The technique proposed, though designed for a particular pilot outfall in a limited area of the Municipality of Genoa, could be applied without any particular difficulties to all old outfalls and to new ones. It could also be used for the monitoring of other environmental problems, such as: - assessment of the discharge parameters of industrial plants in the sewage system and; - determination of the mixing of waters in caption basins. In May 2005, a follow-up ex-post evaluation was carried out by the LIFE external monitoring team. Its main findings were that the pilot plant is still in operation and that the technology developed by the project is still valid, although it has not been adopted (replicated) so far. According to the beneficiary this is mainly due to the ‘legislation gap’ whereby administrators are not yet required by law to use real-time monitoring systems for the coastal outfalls. The study also showed the costs for the installation of the system and its maintenance are “reasonable” when compared to the entire costs for the installation of a new outfall. The project technology has also been acknowledged by the international scientific community at several conferences and congresses. Notably, the first international conference on Marine Waste Water Discharges (MWWD) was organised by the project team in Genoa, Italy on 27 November - 2 December 2000. Following this, regular conferences are held every second year. The next one will be in Santander, Spain, in 2006.