I agree with Erik Rumbaugh. ...

I agree with Erik Rumbaugh.  Formaldehyde is actually produced by selected bacteria in a bio-digester, and in general is not a problem in wastewater treatment works, except at exceptionally high concentrations.  Many chemical toilets use formaldehyde to inhibit bacterial growth within the toilet system.  However the contents are normally disposed of at wastewater treatment works where they can be bio-degraded.  The following is the conclusion from a report I have attached on a study undertaken in South Africa on formaldehyde use in sanitation:

"The overall conclusion is that the use of formaldehyde in chemical toilets does not pose a
problem to normal wastewater treatment facilities below a conservative estimate of say
20 mg/litre, whether it is a septic tank, aerobic treatment or anaerobic treatment. Given the
low concentration of formaldehyde in the chemicals used, the large dilution when added to
the holding tanks, and the rapid biodegradation of formaldehyde in a wastewater
environment, this is a value which is very unlikely to be reached, of which no examples could
be found. Even in the unusual case of King Shaka airport, the levels of formaldehyde is at
least about four orders of magnitude lower than the level suggested."