Sewage lagoon design using wetlands and other upgrading technologies to achieve non-acutely toxic effluent

One of the key issues of concern to both the Federal and Provincial governments is to identifi whether such sources are acutely toxic to fish and to identi& remedial actions which can be taken reduce any identified fish toxicity as identified using the LCWtest. [...] The first section introduces the background to the regulatory concerns, with respect to lagoon effluent toxicity, which have resulted in the need to prepare a design guideline manual. [...] Although toxicity may be caused by a siigle elevated toxic contaminant, typically toxicity data is dficult to interpret as to the cause of toxicity, due to the complex nature of the contaminants present in the wastewater. [...] Whh the exception of lagoon systems receiving u a high proportion of industrialwastewater, most metals are unlikely to be present in a dissolved form at potentially toxic concentrations in the lagoon effluents,and would be expected to be rapidly diluted to even lower concentrations within the receiving environment. [...] For example, the un-ionized ammonia concentration increases from 0.06210/0 of the total ammonia at a pH of 6.5 and temperature of O“C, to 28.4°4 of the total ammonia at a pH b of 9.0 and a temperature of 20°C (Emerson et al., 1975).