13 Jul What are the signs of a non-functioning effluent pond?
Non-performing effluent systems are instantly recognisable by the presence of persistent surface crusting and their pervasive odour. A common symptom is the formation of a crust, whereby undigested solids form a crust up to 50 cm thick on the surface of the pond. Besides harbouring vermin, insect pests and weeds, this crust creates an anaerobic environment underneath.
The depletion of oxygen in the water, combined with lack of sunlight, reduces microbial digestion. Nutrients may remain at toxic levels or settle within the sludge, where they become “locked up” in forms that are unavailable to plants.
The proliferation of anaerobic bacteria can lead to an increase in hydrogen sulphide (i.e. rotten egg gas) and increased pH (i.e. alkalinity). High temperatures can also stimulate anaerobic bacteria at the bottom of the pond.