OVERVIEW MAINTENANCE AND SERVICE

Depending on their design, chemical-physical wastewater systems must be operated in accordance with § Section 60 paragraph 1 WHG (Water Resources Act) in accordance with the state of technology or the generally recognized rules of technology. This can be done by expert operating personnel or by an external company. The requirements for expertise are defined in DWA-M 1000. In addition to the Quality assurance system (e.g. ISO 9001) and a certified WHG specialist company certificate (e.g. for maintenance work on AwSV-LAU systems (chemical storage tanks)), the specialists (internal or external) actually carrying out the work must have appropriate training in the respective profession, demonstrable knowledge of civil, administrative and environmental criminal law, industrial safety and the generally recognized rules of technology, which must be checked by the responsible operator manager.

Appropriately trained personnel are available for the maintenance of systems, including those from other manufacturers, within the scope of the service range, i.e. industrial, chemical-physical wastewater treatment systems.

Filter systems are often part of chemical-physical wastewater systems. Depending on the filling, these are called sand filters, gravel filters, multi-layer filters or media filters. In addition to regular backwashing, and particularly in the case of multi-layer filters with an activated carbon layer, these require regular refilling of the activated carbon by the operator. In addition to the actual maintenance of the system mimicry, the contents of the gravel filter may also be emptied as part of the maintenance. If there is a clogging, e.g. due to a clear water discharge before the end of the sedimentation phase in a batch treatment, it is determined whether this can be treated chemically and what the cause is, as the mining removal of clogging in gravel filters is often not very economical.

Larger quantities of filter medium are emptied using suction or turbine trolleys.

An ion exchanger system and selective exchanger system are filled with ion exchangers that are subject to wear. Depending on the application and resin, it may be necessary to replace the resin or the ion exchanger after a few years. Cation exchange resins have a typical service life of 10-15 years, anion exchange resins of 7 to 10 years, although this can be reduced to less than 2 years due to demanding operating conditions such as oxidative substances, biology or mineral oils.

Depending on the ingredients present in the inflow to the ion exchanger, precipitation may occur in the resin bed as an undesirable reaction. To remove some of these precipitation products, input materials that are otherwise incompatible with ion exchange resins must sometimes be used in order to dissolve the precipitation products via chemical conversion. Alternatively, a resin exchange and separation of the wastewater streams can be the result.

Chemical storage tanks from 220L (e.g. for hydrochloric acid and caustic soda) are so-called AwSV storage systems (storage, filling and handling (LAU) systems) and require regular, at least annual, maintenance in accordance with AwSV. Up to hazard level B, this can generally be carried out by the operator’s own expert personnel for completely visible, above-ground systems. In all other cases, a WHG specialist company is required. In particular, this also applies to installations that are hazard level A installations, but which are not completely visibly installed including the pipelines associated with the system (e.g. via a wall duct).

As part of the maintenance, the tank and the associated piping are inspected, the system documentation is inspected and the tank’s safety devices are checked.

An industrial reverse osmosis system, including the necessary pre-treatment such as system separators, softening, etc., requires regular maintenance over its entire service life. According to DIN EN 806-5:2012-04 Annex A.1 in conjunction with DIN EN 12729:2020, an inspection by the operator at least every six months and annual maintenance of the system separator at the drinking water network transfer point is required.

As part of the maintenance of a reverse osmosis system (RO system), the various operating parameters of the system and any ancillary systems, such as upstream softeners, system separators, etc., are checked and any safety systems are triggered. Typically, the membranes in reverse osmosis systems are replaced after between 5-7 years, depending on how much they are used. Indicators that a membrane change may be necessary at an earlier stage are, for example, an increase in the required pressure of the high-pressure pump and/or a drop in the permeate output at a constant temperature.