DWA-M 760: What the New Guideline Means for Sewer Network Operators and Municipalities

Grease in wastewater is not a new problem — but its consequences are underestimated. Fatty acids from kitchens and food service bind with calcium in the sewer to form soap-like deposits known as fatbergs. These narrow pipes, create anaerobic conditions and promote the formation of hydrogen sulphide (H₂S).

H₂S is not just odour-intensive — it is biogenically aggressive. In moisture it oxidises to sulphuric acid, which destroys concrete sewers from within. For sewer operators this means: increased rehabilitation costs, shortened service lives, and in densely populated areas, acute complaints from odour emissions.

Connections from food service, communal catering and food processing are particularly affected. A single poorly maintained grease trap can degrade the condition of entire sewer sections.

Guideline M 760 of the German Association for Water, Wastewater and Waste (DWA) defines requirements for the treatment of fat-containing wastewater along the entire disposal chain. New compared to earlier regulations: the focus is no longer exclusively on the grease trap as a stand-alone structure, but on the systemic context.

In practice this means: the effectiveness of a grease trap alone is no longer sufficient as evidence. Sewer network operators and municipalities must assess the actual fat input into the sewer — via influent measurements, inspection data and operating logs. Indirect dischargers (restaurants, commercial kitchens) are held more accountable.

Important for practitioners: the guideline explicitly acknowledges that mechanical separators and biological measures can act in a complementary way. Where grease traps reach their limits — for example with high temperature fluctuations, short retention times or biologically difficult fatty acid combinations — supplementary measures are legitimate and effective.

lipasanF® is a biological product based on selectively cultured lipolytic bacterial strains. It is dosed directly into the grease trap or the sewer influent and breaks down triglycerides enzymatically — before they combine into solid deposits.

Its effectiveness has been verified by measurements in several municipal pilot projects. Amperverband Bayern documented 25 m³ of biologically degraded fat over a twelve-week measurement period — with a measurable reduction in floating sludge and H₂S concentration in the influent shaft. Similar results were recorded in Groß-Gerau, Pfungstadt and at the LINEG water association (North Rhine-Westphalia).

These projects show that biological fat degradation is not a replacement for mechanical cleaning — but a systemic complement that addresses exactly where grease traps alone are insufficient: in the sewer network, in the influent and in the biological treatment stage.