Occurrence and removal of protozoan cysts and helminth eggs in waste stabilisation ponds in Marrakech

Abstract

The present study aimed to determine the occurrence and removal of protozoan cysts and helminth eggs from municipal wastewater by pilot waste stabilisation ponds in the arid climate of Marrakech (Morocco). Protozoan cysts detected in raw wastewater at the entrance of the system were identified as Entamoeba histolytica, Giardia sp. and Entamoeba coli at a mean concentration of 1.5×104 cysts/l. Helminth eggs identified were Ascaris, Trichuris, Hymenolepis, Enterobius and Taenia with an average of 7.6 eggs/l. The effluent at the system outlet did not contain detectable cysts or eggs. Sludge samples collected in the pond basins resulted in detection of protozoan cysts and helminth eggs. Sedimentation therefore seems to be the main factor for cyst and egg elimination during wastewater treatment by waste stabilisation ponds. This phenomenon leads however to parasite accumulation in the sediment.

The survival and dispersal of Taenia eggs in the environment: what are the implications for transmission? A systematic review

“…egg presence in the influent/effluent of wastewater treatment systems. Country Wastewater treatment system Egg recovery Influent Effluent Year of publication Reference Morocco Activated sludge and natural lagoon Modified Bailenger method (sedimentation, centrifugation, flotation and McMaster) 5.28 eggs/l ( N = 6) and 0 eggs/L ( N = 6) 0 eggs/l ( N = 6) and 0 eggs/L ( N = 6) 2018 [ 110 ] Colombia Series of anaerobic, facultative and maturation ponds Modified Bailenger method 63 helminth eggs/l ( N = 8) 0 eggs/l ( N = 8) 2002 [ 111 ] Iran Activated sludge Natural lagoons Modified Bailenger method Low number present in 2 of 8 plants (3 and 1.25 eggs/l) ( N = 16/plant) < 1 egg/l ( N = 16/plant) 2006 [ 112 ] Morocco Stabilization ponds Bailenger method 0.1 eggs/l ( N = 48) 0 eggs/l ( N = 48) 2000 [ 113 ] Tunisia Activated sludge Stabilization ponds Bailenger method From 28 to 208 eggs/l ( N = 174) From 17 to 52 eggs/l ( N = 174) 2009 [ 88 ] Colombia Anaerobic biodigestors …”

Waste Stabilization Ponds

“…to 2 f,g~0 to 1 f,g 2.2 (1.9 to 2.4) a Sources: (Al-Salem and Lumbers, 1987;Anceno et al, 2007;Araki et al, 2001Araki et al, , 2000Ayres et al, 1993;Bausum et al, 1983;Bouhoum et al, 2000;Da Silva et al, 2011;De Oliveira et al, 2011;Dixo et al, 1995;García et al, 2008;Grimason et al, 1996aGrimason et al, , 1996bHachich et al, 2013;Hassani et al, 1992;Hewitt et al, 2011;Joshi et al, 1973;Konaté et al, 2013aKonaté et al, , 2013bMara and Silva, 1986;Nupen, 1970;Oakley, 2004;Oragui et al, 1995Oragui et al, , 1987Ouazzani et al, 1995;Rao et al, 1981;Pescod, 1992, 1991;Schwartzbrod et al, 1989Schwartzbrod et al, , 1987Stott et al, 2003;von Sperling and Mascarenhas, 2005;von Sperling et al, , 2003von Sperling et al, , 2002Young et al, 2016). Typical log 10 removals are arithmetic mean values of the log 10 removals reported in the literature; typical ranges are +/-one standard deviation of the mean.…”

Diagnostic tools for the detection of taeniid eggs in different environmental matrices: A systematic review.

“… Quantitative N.M. N.M. 6–10 ≤ 24 h Vietnam Noda et al, 2009 Sedimentation by centrifugation, ZnSO 4 flotation (s.g. 1.3) and microscopy Wastewater Echinococcus / Taenia spp. Quantitative N.M. N.M. 7 ≤ 24 h Morocco Bouhoum et al, 2000 7 28d South Africa Amoah et al, 2018 Filtration, ZnSO 4 flotation (s.g. 1.3) and microscopy Wastewater Echinococcus / Taenia spp. Quantitative Se: 80–90% Sp: 99% N.M. 4 ≤ 12 h Mexico Jimenez et al, 2016 Modified Bailenger technique based on sedimentation, ethyl acetate and ZnSO 4 flotation (s.g. 1.3) with microscopy Wastewater Echinococcus / Taenia spp.…”

“…Mostly, the sample is either filtered, left to settle, or centrifuged for sedimentation, after which the supernatant is discarded and a saturated zinc sulfate solution added ( Jimenez et al, 2016 ). The flotation samples are generally aliquoted and centrifuged with a cover slip on top, or directly examined under the microscope without centrifugation ( Bouhoum et al, 2000 ). Alternatively, the supernatant is poured through a sieve, after which the contents of the sieve are washed and centrifuged for final examination of the sediment ( Amoah et al, 2018 ).…”