PhD ThesisThis research involved survey, laboratory and field studies. First, an evaluation of the
present status of intestinal parasitic infections was made in the Jordanian population.
Second, laboratory investigations were conducted on the development of a new technique
to detect the viability of Ascaris eggs. Third, field studies were carried out to investigate
the survival and occurrence of indigenous parasite eggs and indicator pathogens in
domestic waste sludges in Jordan. Field investigations were also conducted on the effect
of open natural drying beds on the inactivation of parasite eggs and bacterial pathogens.
The results of this study and a survey of available literature indicated a need for a
universally accepted definition of a "viable" Ascaris egg.
A staining technique for detecting Ascaris egg viability was developed in conjunction with
research studies of Ascaris eggs in sludge. The vital stain Crystal violet showed high
correlation with the incubation method, and was more precise than the other stains tested.
Crystal violet showed the best spontaneous detection of changes in egg viability and,
within certain limits, it was found to be a strong indicator of the state of egg viability;
furthermore it did not show any evidence of toxicity. In the staining method, Crystal
violet stain is added directly to an egg preparation and observations are then made
immediately using a light microscope. The results are available in only 10 minutes,
compared to the 30 days required for the Incubation method. Since only stained or
unstained eggs were observed, the method is less subjective than the Incubation method.
In order to evaluate the versatility of the staining method, the effect of UV light and
temperature was also investigated.
The ultimate disposal of domestic wastewater treatment plant sludges has been recognised
recently as a problem in Jordan, and has never previously been investigated from the point
of view of pathogen survival and transmission. This study showed that a huge volume of
sludge (36,600 m3 dry weight basis) accumulated from 1985-1993 in six anaerobic ponds,
now requires desludging, treatment and disposal. Anaerobic pond sludges displayed some
physico-chemical similarities to digested primary sludge.....This research concludes that sludge drying beds can be an effective method for
inactivating parasite eggs, particularly in warmer geographic locations, and thus the
treated sludge can be considered safe in terms of parasite transmission for application to
agricultural land. Ascaris eggs had degenerated when the percentage of total solids was
recorded as more than 88%; this took a shorter time in sand than in gravel drying beds.
The inactivation of Ascaris eggs in drying beds is probably due to more factors than
desiccation alone. Temperature, oxygen content, solar radiation, exposure time, mould
activity, type of sludge, type of media etc., may also affect survival of the eggs. Anaerobic
pond sludge bacterial counts showed higher resistance to desiccation and treatment
conditions in drying beds compared with oxidation ditch sludge.European Development Fund of the European
Commission, The British Council:
The Arab British Chamber Charitable Foundation