Occurrence and removal of Giardia and Cryptosporidium at the Goreangab reclamation plant

Abstract

This paper deals with the occurrence of Giardia and Cryptosporidium in the water sources available for the Goreangab Reclamation Plant (GRP) and the subsequent removal during treatment at the reclamation plant. Giardia is detected more often than Cryptosporidium. 60% of the time it is detected in the samples from the dam and in 55% of the samples from the maturation pond effluent. During the investigation, Giardia was detected in the final water 5% of the time and Cryptosporidium 2% of the time. The maximum Giardia cysts detected in a sample was 30, the 99% percentile was 20 and the 97% percentile 10 cysts. A maximum of 20 Cryptosporidium oocysts was detected in a sample. The 99% percentile counted 6.2 oocysts and the 97% percentile 0 oocysts. From the data presented it is clear that the polluted dam water has the same risk level of Giardia and Cryptosporidium pollution as treated wastewater effluent. This emphasises the fact that the sources should be monitored continuously for these parasites. The sporadic high counts of Giardia and Cryptosporidium in the raw water sources indicate that a multiple-barrier approach must be followed to ensure the safe operation of even conventional treatment plants using polluted source water. No correlation could be found between cyst and oocyst removal and other water quality parameters. The advocating of a final water turbidity of 0.1 NTU and the use of particle counters can only be supported by these findings, as it is possible to achieve a turbidity of less than 0.1 NTU at the sand filter outlet, even in a developing country like Namibia. The challenge lies with the maintenance of equipment and vigilance of the operators.

Neglected tropical diseases of Namibia: Unsolved mysteries

“…In 2001, Menge et al detailed the occurrence of Giardia and Cryptosporidium in the reclamation plant outside of Windhoek (Khomas region) (Menge et al, 2001). Between 1996 and 1999, Giardia crossed into the water supply five times, endangering the health of Windhoek residents.…”

Zoonoses: a potential obstacle to the growing wildlife industry of Namibia

“…They have been found in most surface waters, where their concentration is related to the level of faecal pollution or human use of the water ( 125 ). The sporadic high counts of Giardia and Cryptosporidium in the Namibian raw water sources indicate that a multiple-barrier approach must be followed to ensure the safe operation of treatment plants using polluted source water ( 126 ).The role of wildlife in transmitting Giardia to humans has been controversial although a variety of Giardia species has been isolated from wild mammals, birds, amphibians and reptiles ( 127 ).…”

Fundamental membrane processes, science and engineering

“…UF guarantees a constant water quality at low cost, virtually independent of the feed water quality. Multiple large scale plants are today in operation in The Netherlands, Belgium, Germany, Spain, Namibia, Singapore, Kuwait and the USA (Futselaar et al, 2004;Von Gottberg et al, 2003;Menge et al, 2001;Lim, 2005). UF has also been accepted as an alternative to conventional pretreatment for brackish surface water RO systems.…”