NOVELTY - Complete anaerobic degradation of polymer mixtures containing: (a) 25-95 wt.% polyhydroxyalkanoate comprising poly-4-hydroxybutyrate, poly-3-hydroxybutyrate, poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate and poly(3-hydroxybutyrate-co-4-hydroxybutyrate); and (b) 5-75 wt.% an aliphatic-aromatic polyester containing (i) 5-36C dicarboxylic acid derivatives or 5-36C dicarboxylic acids, (ii) terephthalic acid derivative or a terephthalic acid, (iii) 2-8C alkylene diol or 2-6C oxyalkylene diol, (iv) at least one polyfunctional compound, is claimed.    USE - The method is useful for complete anaerobic degradation of polymer mixtures.    ADVANTAGE - The method enables production of mechanically strong films, which exhibit good anaerobic biodegradability and good processability.    DETAILED DESCRIPTION - Complete anaerobic degradation of polymer mixtures containing: (a) 25-95 wt.% polyhydroxyalkanoate comprising poly-4-hydroxybutyrate, poly-3-hydroxybutyrate, poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate and poly(3-hydroxybutyrate-co-4-hydroxybutyrate); and (b) 5-75 wt.% an aliphatic-aromatic polyester containing (i) 65-95 mole% 5-36C dicarboxylic acid derivatives or 5-36C dicarboxylic acids, (ii) 35-5 mole% terephthalic acid derivative or a terephthalic acid, (iii) 98-100 mole% 2-8C alkylene diol or 2-6C oxyalkylene diol, (iv) 0-2 wt.% at least one polyfunctional compound containing at least two isocyanate-, isocyanurate-, oxazoline- or epoxide-groups or at least three alcohol- or carboxylic acid groups, is claimed. INDEPENDENT CLAIMS are also included for:    (1) complete anaerobic degradation of packaging for bio-products, which contains polymer mixtures containing component (a) and component (b); and    (2) disposing the bio-products into a biogas plant, comprising collecting or filling the bio-products in a package which contains polymer mixtures containing component (a) and component (b), collecting the bio-products in the package from a waste disposal company and supplying the bio-products in the package to anaerobic fermentation in a biogas plant.