(FR2730226-A1)      Purification of waste comprises feeding water to several fixed-culture biological filters or other fixed-culture units operating in parallel at least once and at a constant rate, the number of filters to be fed being varied as a function of the total rate of flow.    The treatment pref. involves: (i) measuring, for each bio-filter, the cumulative duration or rate of flow over a given period of time, as well the amt. of time that the filters are not fed; and (ii) varying the order in which the filters are fed according to cumulative duration or rate of flow. The constant rate of flow to each filter corresponds to its max. purification capacity.    USE -   The process is applicable to municipal or industrial waste water, and in the purification of water for drinking purposes.    ADVANTAGE -   The performance of bio-filters is improved, fewer filters are used and nitrification yields are improved.    (JP8238493-A)      Purification of waste comprises feeding water to several fixed-culture biological filters or other fixed-culture units operating in parallel at least once and at a constant rate, the number of filters to be fed being varied as a function of the total rate of flow.    The treatment pref. involves: (i) measuring, for each bio-filter, the cumulative duration or rate of flow over a given period of time, as well the amt. of time that the filters are not fed; and (ii) varying the order in which the filters are fed according to cumulative duration or rate of flow. The constant rate of flow to each filter corresponds to its max. purification capacity.    USE -   The process is applicable to municipal or industrial waste water, and in the purification of water for drinking purposes.    ADVANTAGE -   The performance of bio-filters is improved, fewer filters are used and nitrification yields are improved.    (US5795481-A)      Purification of waste comprises feeding water to several fixed-culture biological filters or other fixed-culture units operating in parallel at least once and at a constant rate, the number of filters to be fed being varied as a function of the total rate of flow.    The treatment pref. involves: (i) measuring, for each bio-filter, the cumulative duration or rate of flow over a given period of time, as well the amt. of time that the filters are not fed; and (ii) varying the order in which the filters are fed according to cumulative duration or rate of flow. The constant rate of flow to each filter corresponds to its max. purification capacity.    USE -   The process is applicable to municipal or industrial waste water, and in the purification of water for drinking purposes.    ADVANTAGE -   The performance of bio-filters is improved, fewer filters are used and nitrification yields are improved.    (EP725042-B1)      Purification of waste comprises feeding water to several fixed-culture biological filters or other fixed-culture units operating in parallel at least once and at a constant rate, the number of filters to be fed being varied as a function of the total rate of flow.    The treatment pref. involves: (i) measuring, for each bio-filter, the cumulative duration or rate of flow over a given period of time, as well the amt. of time that the filters are not fed; and (ii) varying the order in which the filters are fed according to cumulative duration or rate of flow. The constant rate of flow to each filter corresponds to its max. purification capacity.    USE -   The process is applicable to municipal or industrial waste water, and in the purification of water for drinking purposes.    ADVANTAGE -   The performance of bio-filters is improved, fewer filters are used and nitrification yields are improved.