Risk husk is fairly tough and difficult to digest. Assuming your UASB is a small-scale one, a suggestion, grind the husks into small pieces and pre-mixed with the sewage before feeding into UASB. This might not give a good results if the bacteria consortium initially used in the UASB is not acclimatized to digesting the risk husks. A suggestion, you need to prepare sufficient amount of seed of bacteria consortium in a separate batch process using the premixed composition. Then, this acclimatized seed of consortium can be used in the UASB. This might give a better result.
many Thanks for you Jobrun Nandong you are right, i think it is logic also to soak rice husk with sewage wastewater to prevent its floating inside the reactor
First you need to grind rice husk and then make a suspension 1: 100 flour rice husk and 100 parts of water and let the mixture for 7 days and then inoculate the UASB , this is very good.
Thank you for your scientifically logic answer, I think Soaking for 7 days are too much and may be impossible for life application. Actually only one day soaking may be useful and easy for applied application.