Ciliated protozoa (ciliates) are an important component of the microbial community in aerobic biological wastewater-treatment plants with about 175 species reported. They commonly number 50 million cells per litre in the mixed liquor of the activated-sludge process where their major role is the removal of dispersed bacteria by predation. It has long been known that ciliates can be used as reliable indicators of effluent quality in biological aerobic sewage-treatment processes. The advantage of using ciliates as bioindicators is that of speed, with an accurate prediction of effluent quality being available within an hour or two of sampling. Ciliates are rarely used on site in this way, however, mainly because of the difficulty that non-specialists have in identifying them. The main aim of this project is to produce a multimedia, user-friendly guide that can be used by specialists and non-specialists alike for both training and routine monitoring.

Above: Amphileptus pleurosigma, a free-swimming ciliate. Scale bar = 50 micrometres.

Download Video clip Amphileptus
claparedei (2 Mb)

Showing typical swimming activity, several peripherally-located
contractile vacuoles and two ovoid macronuclei.

Download Video
clip Euplotes moebiusi (1.6 Mb)

(1) Dorso-ventral view of stationary cell, showing pattern of cirri
on ventral surface; (2) lateral view of moving cell, showing typical
crawling activity on floc.

Download Video clip
Carchesium polypinum (2.5 Mb)

Low magnification - showing that separate branches of the colony
can contract independently of one another. Higher magnification
- showing; 1, zooids (mature adult cells) on end of stalks, and
2, developing telotroch (larval stage) with its extra row of cilia
near the posterior end of the cell which it uses for locomotion.

In order to mitigate the problem of recognising organisms observed
in fresh samples under the microscope, photographs and/or video
clips in vivo are provided in addition to descriptions and
line diagrams. There are video clips for the 75 or so species most
commonly encountered and/or which are of the greatest indicator
value. These digitised images are included in order to show key
behavioural patterns, eg swimming, feeding etc. Taxonomic descriptions
are presented in a way that emphasises the differences between the
species known to occur in wastewater treatment, rather than emphasising
the features of systematic importance.

Above: Euplotes aediculatus, a crawling ciliate. Scale bar = 50 micrometres.

Samples are identified by date and location within the sewage-treatment
plant and a profile of ciliate diversity is built using the system.
The key is essentially pictorial and multi-entry, meaning that users
can skip questions that they cannot answer with confidence. Once
an identification is reached, the user can review all data associated
with the species and confirm or decline the identification for accumulation
into the sample profile. There are numerous short-cuts that can
be taken for more experienced users. Species are quantified on a
scale of abundance (eg few, several, many) rather than counted.