Use of humin in the form of humic acid or its salts, by converting it with redox catalysts or fermentation media using films or membranes impregnated with microorganisms, is new. The product is used for one of the following processes:    (a) as a catalyst or sorbent for abiotic hydrolysis and/or oxidation of chalcogenic sulphur or selenium compounds in the gaseous phase in the presence of free and/or capillary condensed aqueous and/or polar and/or salt-containing fluid phases, to form 1 of the compounds, chalcogen hydrogen, elementary chalcogen, poly-chalcogenide, thionate, polythionate, chalkogenite or chalcogenate;    (b) as a catalyst for abiotic oxidation of 1 compound containing sulphite, thiosulphate or polythionate groups, where the compounds are dissociated or undissociated in the aqueous phase;    (c) abiotic oxidation of compounds containing hydrogen and 1 of the element phosphorus, arsenic or antimony in the presence of free and/or capillary condensed aqueous and/or polar and/or salt-containing fluid phases, to form 1 compound containing these elements and oxygen;    (d) abiotic phosgene hydrolysis;    (e) abiotic oxidation and/or sorption of 1 element or compound containing iodine, precious metals, mercury or zinc in the gaseous or aqueous phase;    (f) heavy metal precipitation in the presence of sulphur or a sulphur compound, to produce a heavy metal sulphide;    (g) abiotic and/or biotic reduction of nitro-organic, halo-organic or oxyran-organic compounds in the presence of free, capillary condensed aqueous, polar and/or salt-containing fluid phases;    (h) biotic decomposition of the surface layer of sewage during water purification;    (i) biotic oxidation of sulphide-containing ores or sulphides to give the corresponding heavy metal sulphates;    (j) biotic decomposition of organic impurities in water or soil;    (k) biotic decomposition of microorganisms on the surface of plant roots or fungal mycelia or hyphae in water or soil;    (l) for street cleaning;    (m) for the care of plants and/or fungal cultures (i.e. as a fertiliser);    (n) as a fertiliser for plants/fungi, with the addition of root and/or mycelium and/or mycorrhiza substrate, and    (o) for the abiotic decomposition of pollutants, when used in combination with 1 other anti-pollutants.    Also claimed are coagulated particle agglomerates useful as flow-release fertilisers, these are made from coagulated humic acid.    ADVANTAGE -   The use of humic acid avoids the need for expensive catalysts such as platinum and activated charcoal, and complex builders, e.g. lanthanide/actinide heptane dioates. Such materials are also difficult to produce and often form environmentally damaging side products. Faster reaction times are achieved using humic acid. The purification can also be carried out at neutral pH values, rather than under alkaline conditions.