A kraft mill, even by utilizing the best available technology,
cannot be made completely odour-free. However, there are several
sulphide-free and non-sulphur pulping methods. Among these, sodaanthraquinone
(AQ) pulping process seems to be promissing.

The most practised chemical to-day is the kraft process. 95% of the present production of chemical 74 Pulp yield can be increased by using polysulphide, H2S or AQ
in the cook. The first two are used exclusively in kfraft cooking, and
so the odour problem cannot be overcome. AQ on the other hand,
is also suitable in a sulphur-free cook which eliminates the odour
problem of the pulp mill. Soda-AQ pulping is more suitable with
hardwoods.