TABLE 4.

Percentage of HAV-positive wastewater samples in influents and effluents and percentage of virus removal by wastewater treatment process

Season	Wastewater treatment process
	Conventional activated sludge (medium charge)a			Extended aeration oxidation ditch activated sludge (low charge)b			Extended aeration activated sludge (low charge)c
	% HAV-positive influent samples	% HAV-positive effluent samples	% virus removal	% HAV-positive influent samples	% HAV-positive effluent samples	% virus removal	% HAV-positive influent samples	% HAV-positive effluent samples	% virus removal
Winter	60	40	33.3	42.9	7.1	83.3	100	14.3	85.7
Spring	50	57.1	0	42.9	50	0	85.7	14.3	83.3
Summer	78.6	85.7	0	64.3	35.7	44.4	100	14.3	85.7
Autumn	91.7	75	18.2	50	9.1	81.8	100	50	50
Total	69.1	63.6	7.9	50	26.4	47.2	96.3	22.2	76.9

^aTreatment used by Sousse-South and Dekhila STPs.

^bTreatment used by Sahline and Kairouan STPs.

^cTreatment used by Jammel STP.