The MSB model of pollution flushing from a tidal basin, which is based on the analytical tidal prism model developed by Barber, has been applied to embayments with non-constant bathymetry and constant pollution loading. This paper extends the versatility of the MSB model by including alternative pollution loading functions. The model, written in Stella (Stella is a software product and trademark of High Performance Systems, Inc. Hanover, NH 03755 USA), can use both the internal functions of Stella as well as a user-defined functional representation that is part of the Stella toolset. The morphology of a pulse function applied at different times throughout the tidal cycle is studied. Results of these simulations are applied to answer a hypothetical yet useful question: if a certain mass of pollutant must be loaded into a tidal embayment, when should this loading be applied to minimize the time for the concentration to 'relax' to a certain critical level? These results and the multiple possibilities for extending the MSB model are explored.

The Microflush-Biofil(MB) toilet system, a prototype marriage of a macroorganism enhanced aerobic digester and an innovative valve that flushes on just 150 cc of water has proven to be an effective sanitation solution for developing world tropical communities. This paper examines the sustainable elements of this technology. We present the approach of the Ghana Sustainable Aid Project in readying the technology for a decentralized approach in moving to a global scale. The challenges and opportunities associated with such an ambitious plan.

The MSB single-embayment model of pollution flushing from a tidal basin has been applied to Great Salt Pond on Block Island and the results compared to an unpublished Rhodamine dye study conducted in 1986. The MSB model is based on the analytical tidal prism formulation developed by Barber. Both approaches have previously been validated against physical hydraulic modelling tests conducted on an idealised constant-depth rectangular basin, and the MSB model has been found to give excellent agreement against the laboratory data. However, until this present work, the MSB model has not been applied to a real embayment.The present paper details a simulation of pollution flushing from Great Salt Pond following the release of Rhodamine dye. Results for various values of the pollution return-flow parameter, b, have been obtained and the agreement between the measured dye concentration data and the model predictions is shown to be very good for a suitably chosen value of b.

The Microflush toilet system, a low-flush off-grid macro-organism enhanced aerobic digester has been prototyped and shown to be an effective toilet solution for rural communities in the tropical developing world. The system rapidly filters solids in the waste stream from liquids-urine and greywater from hand washing. The solids are digested and vermi-composted with e. fetida and other macro-organisms resulting in high mass reduction and pathogen removal. The resulting compost is harvested every 2-3 years. Successful field trials have been conducted on the system. This paper examines options for removing pathogens in the liquid filtrate. SOLDIS including solar thermal, UV and combination processes as well as SOLDIS-enhanced urine-ammonia treatment are examined. Dynamic models for SOLDIS thermal and UV processes have been developed in order to influence and study the effectiveness of alternative designs. Physical, economic and behavioral factors for each option are considered. Successful field trials will result in a virtually closed sustainable on-site sanitation solution with water used for handwashing, the resulting greywater used for micro-flushing, the blackwater processed to remove pathogens and the final solids product used for agriculture or other productive purposes with the entire process being off-grid.

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