Sawdust toilet smells slightly

I'm somewhat new to compost toilets and have begun using a bucket toilet with a urine diverter with dry sawdust as the cover material. This is inside a very small cottage (120 sq ft). Most of the time there is no odor but sometimes there is. It's not offensive really but its not exactly desirable either (and its hard to describe). I'm wondering what I can do to decrease odor. Each deposit is covered completely with sawdust, usually two handfuls or so. I know in the Humanure Handbook he recommends using only rotted sawdust, not dried sawdust. I'm going to try to experiment with this but I'm hoping I don't end up with a fungus gnat problem with the added moisture

Any advice would be greatly appreciated

I've used such buckets for years. When I lived in an apartment where I wanted absolutely no risk of odor for visitors or landlord, I used semi-dry clay soil as the covering, which killed the odor completely, like cat litter. Since I moved onto private property I've used sawdust, usually semi-composted, but the bucket was usually in an outbuilding. You will get more odor with an organic covering like that. A few hints at minimizing this have come over the last few years:
1. Be sure the sawdust is NOT completely dry.....Somewhat moist is best.
2. Add about 10% ashes to the sawdust.
3. Another hugely helpful idea, not having to do with odor but with neatness when emptying the buckets.....line the buckets with newspaper, overlapping. The paper drops out with the rest and composts with it, leaving your buckets hose-rinse washable!

I've never tried this, but I wonder if charcoal left over from a wood fire would help. I happen to use wood for cooking and purposely have one stove set up for the production of biochar. I use biochar in the urine collection bucket. Amazingly no odor. If crushed fine, I wonder if it would help in the poo bucket. Just a thought.

...Su Ba
www.kaufarmer.blogspot.com