To conserve water and also for avoiding the hazardous chemicals in cleaning, biochar is one of the means. The plates used for eating at the GEO research center are cleaned using biochar powder (rice husk biochar is ready to use). Biochar helps in cleaning the plate, including oily matter. The plate turn very clean and odor free, and ready to use it again. All this with out using any water. Very little water could be sprinkled on the plate to wipe it at the end, if required.
One could take the help of chicken too and also helping them with feeding left over food in the plate.
The biochar after cleaning the plates attains more value as a soil amendment.