Laboratory experiments and simulation analysis to evaluate the application potential of pressure remote RTC in water distribution networks.

Experimental tests were performed to demonstrate applicability of remote real time control (RTC) of pressures for leakage reduction in water distribution networks (WDNs). The experimental tests were carried out in a laboratory pilot system equipped with a motorized plunger valve. A RTC system with the adoption of an integral-type control algorithm was implemented in order to adjust the valve on the basis of pressure measurements acquired in real time. A numerical model of the pilot system was used to verify the suitability of the hypothesis of steady-state conditions in simulating the laboratory tests. The results of the experiments show that, under appropriate calibration of the control algorithm, the RTC system is able to perform effective control of the pressure. Comparison between results of the simulations and experiments reveals that the steady-state model describes correctly the evolution of the pressure control processes observed in the laboratory pilot system, thus opening perspectives for testing remote RTC schemes for leakage management in real WDNs.

A model for non-uniform sediment transport induced by flushing in sewer channels.

A novel unsteady flow numerical model for the simulation of the transport of non-uniform non-cohesive sediment mixtures (SM) during flushing operation in sewers is presented in this paper. The model was applied to the case of a flush experimental test that was recently carried out in a combined sewer channel of the sewer system of Paris city that exhibits depositional problems due to relatively coarse sediments. The model output was compared to the results of the field experiments as well as to those obtained with a model for the transport of uniform sediments (US). The model for SM provided a reliable interpretation of the selective transport of the sediments deposited in the channel bed as induced by the flush. The comparison showed the model for SM to provide an enhanced description of the erosional effects of the flush on the deposits, including improved evaluation of the volume of sediments flushed out of the experimental channel in the field.

A field experiment to evaluate the cleaning performance of sewer flushing on non-uniform sediment deposits.

The results of a field experiment to evaluate the scouring effect of a single flush operation in a compound-section sewer channel in Paris, France, are presented in this paper. Full monitoring of the experiment allowed identifying flush-related transport/deposition key processes playing a role on the evolution of the deposited sediments. Overall, the flush was able to scour sediments accumulated over the channel invert up to a significant distance from the gate. The analysis of the results revealed that the flush had a different impact on the various sediments present in the bed mixtures, with most of the eroded volume including sediment particles smaller than the median grain size.

Urban rainwater harvesting systems: Research, implementation and future perspectives.

While the practice of rainwater harvesting (RWH) can be traced back millennia, the degree of its modern implementation varies greatly across the world, often with systems that do not maximize potential benefits. With a global focus, the pertinent practical, theoretical and social aspects of RWH are reviewed in order to ascertain the state of the art. Avenues for future research are also identified. A major finding is that the degree of RWH systems implementation and the technology selection are strongly influenced by economic constraints and local regulations. Moreover, despite design protocols having been set up in many countries, recommendations are still often organized only with the objective of conserving water without considering other potential benefits associated with the multiple-purpose nature of RWH. It is suggested that future work on RWH addresses three priority challenges. Firstly, more empirical data on system operation is needed to allow improved modelling by taking into account multiple objectives of RWH systems. Secondly, maintenance aspects and how they may impact the quality of collected rainwater should be explored in the future as a way to increase confidence on rainwater use. Finally, research should be devoted to the understanding of how institutional and socio-political support can be best targeted to improve system efficacy and community acceptance.