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A wastewater tertiary treatment system based on membrane ultrafiltration and fed with secondary-treated municipal wastewater was evaluated for its Giardia cyst and Cryptosporidium oocyst removal efficiency. Giardia duodenalis (assemblages A and B) and Cryptosporidium parvum were identified in feed water but were found in filtered water only during occasional failure of the filtration system.Treated wastewater can be utilized as an alternative water source for agricultural irrigation, but advanced treatment is required to minimize its potentially negative impact on public health. In particular, chlorine-based disinfection tools cannot destroy the resistant stages of protozoan parasites Giardia and Cryptosporidium (7, 11), and there is an urgent need for specific treatments to remove these protozoa from wastewater. Membrane technologies have a strong potential in this respect, and ultrafiltration (pore size of 0.002 to 0.1 m) can achieve complete removal of protozoan cysts (4 to 15 m) by physical sieving (2, 16). This is especially interesting for wastewater reclamation and makes it possible to avoid chemical disinfection and consequent possible formation of toxic by-products (14).In a previous investigation, a pilot-scale membrane system was evaluated for reuse of treated wastewater in irrigation and gave very good performances in terms of suspended solids and bacterial removal (17). This work refers to the same experimental plant and reports results on (i) the presence of Giardia cysts and Cryptosporidium oocysts in well water used for irrigation in southern Italy and in secondary-treated wastewater from urban areas, (ii) the (oo)cyst removal efficiency of the tertiary treatment system based on membrane filtration, and (iii) the presence of (oo)cysts in soil and vegetables irrigated with well water and water filtered by the above-mentioned method.Wastewater tertiary treatment was carried out at the pilot scale by membrane ultrafiltration using a submerged hollowfiber system. All details of the pilot plant, equipped with a Zenon ZeeWeed membrane module (Zenon Environmental Inc., Canada), were provided in a previous article (17). A simplified scheme of the pilot plant is shown in Fig. 1. The permeate after filtration was collected and stored in six tanks (5 m 3 each). Although each irrigation required about 15 m 3 of water, a total stored volume of 30 m 3 was always available in order to match the continuous plant operation with the discontinuous demand for treated water for irrigation and to have a buffer of treated water in case of possible equipment failures. The test field was located about 100 m from the pilot plant and was connected to the storage tanks by a pipeline. In this experimental field, 2-year studies were carried out to compare, on four crops in succession (fennel, lettuce, chicory, and processing tomato), two types of water: tertiary filtered municipal wastewater and well water commonly used for irrigation.Giardia cyst and Cryptosporidium oocyst detection in water and wastewater was performed acco...

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Giardia and Cryptosporidium spp. are important enteric protozoan pathogens for humans and animals, and have been found to contaminate water as well as edible shellfish all over the world. This is the first study to simultaneously investigate the presence of Giardia and Cryptosporidium in inflowing water and harvested shellfish in a geographically closed environment (Varano Lagoon, Southern Italy). Samples of treated wastewater were collected each month - at the outlet from the treatment plant, and downstream at the inlet into the lagoon - from the channels flowing into the Lagoon, together with specimens of Ruditapes decussatus and Mytilus galloprovincialis from shellfish-farms on the same lagoon. Giardia cysts were found by immunofluorescence (IF) microscopy in 16 out of 21 samples of treated wastewater and in 7 out of 21 samples from downstream water channels, and viable cysts were also detected by a beta-giardin RT-PCR. G. duodenalis Assemblages A and B were identified by small ribosomal subunit (18S-rDNA) and triosephosphate isomerase (tpi)-PCR, followed by sequencing. Cryptosporidium oocysts were found by IF in 5 out of 21 wastewater samples, and in 8 out of 21 samples from water channels. Molecular analysis identified the zoonotic species Cryptosporidium parvum by oocyst wall protein (COWP)-PCR and sequencing. Higher concentrations of Giardia cysts than Cryptosporidium oocysts were registered in almost all wastewater and water samples. IF and molecular testing of shellfish gave negative results for both protozoa. Wastewaters carrying Giardia and Cryptosporidium (oo)cysts are discharged into the Lagoon; however, the shellfish harvested in the same environment were found to be unaffected, thus suggesting that physical, ecological and climatic conditions may prevent contamination of harvested shellfish.

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