The pH values of these solutions are less than 6. They are acidic aqueous solutions that must be free of
- Cyanides (otherwise hydrogen cyanide would be formed!),
- ammonium ions (max. allowed 0.1 mol/L), and
- Any kind of organic substances (e.g. solvents, fats and oils).
Used acids containing nitric acid (e.g. nitrant mixtures) must be neutralized and then disposed of as "Wash and rinse water".
Acid solutions that do not contain heavy metals or other hazardous substances can be neutralized with sodium hydroxide or sodium hydrogen carbonate in equimolecular amounts and then discharged into the laboratory wastewater.
Bases, Alkaline Mixtures, and Mordants
This waste category includes liquid wastes with a pH greater than 8. These are solutions of alkaline hydroxides that must be free from
- cCanides,
- ammonium ions (max. 0.1 mol/L, otherwise ammonia would be emitted!), and
- Any kind of organic substances (e.g. solvents, fats and oils).
Alkaline solutions that do not contain heavy metals or other hazardous substances can be neutralized with equimolecular amounts of hydrochloric acid and then discharged into the laboratory waste water.
Washing and rinsing waters, containing metallic salts.
This category of waste includes aqueous solutions of metallic salts which must be free from
- Cyanides,
- ammonium ions (max. permitted 0.1 mol/L!), and
- Any kind of organic substances (e.g. solvents, fats and oils).
In the case of these aqueous solutions it is possible to achieve significant volume reductions by applying concentration measurements.