Evaluation des risques sanitaire lié à la contamination des éléments traces métalliques des eaux souterraines du Quaternaire des côtes Ouest-Africaine: cas de la côte l’Ouest de Lomé, Togo.

Koudjo ADJE^1,2*, Housseni AHOUDI¹, Kamilou OURO-SAMA¹, Hodabalo DheoulabaSOLITOKE¹,  Kissao GNANDI¹.

1 Université de Lomé, Faculté Des Sciences, Laboratoire de Gestion, Traitement et Valorisation des Déchets, Département de Géologie et Environnement, BP : 1515, Lomé-Togo.

2 Ecole Normale Supérieure d’Atakpamé, Département Sciences de la Vie et de la Terre, 200 BP 80, Atakpamé-Togo

*Email : adjekoudjo@gmail.com, +228 90 74 23 46

Abstract

The problem of water contamination is preoccupying in the cities of Africa. The objective of this study is to assess the health risks linked to the consumption of water from wells in the Kodjoviakopé district (Lomé). To achieve this objective, the analysis of physicochemical parameters such as turbidity, pH and conductivity, as well as certain metallic trace elements (cadmium, lead, iron, arsenic, and chromium) were analyzed in 24 water samples from the wells in this area collected in March 2023. It appears from the analysis of the results that the water is highly mineralized, contaminated with cadmium, lead and arsenic and present a strong contamination factors. In descending order of contamination factor, we note 220 times higher than the WHO standard for arsenic; 33.92 times for lead and 1.76 times for cadmium. The calculated risk quotient is greater than 1 for As, Cd and Pb in both adults and children as well as Cr in children. The overall, collected well water is contaminated. This therefore poses a public health problem. Raising public awareness of the effects of water contaminants and the policy of drinking water supply and sanitation in the area must be a priority for the country’s authorities.

Keywords: groundwater, contaminants, wells, water, west coast, Kodjoviakopé

Résumé

Le problème de la contamination de l’eau est préoccupant dans les villes d’Afrique. L’objectif de cette étude est d’évaluer les risques sanitaires liés à la consommation de l’eau des puits du quartier de Kodjoviakopé (Lomé). Pour atteindre cet objectif, l’analyse des paramètres physico-chimiques tels que la turbidité, le pH et la conductivité ainsi que certains oligo-éléments métalliques (cadmium, plomb, fer, arsenic et chrome) ont été analysés dans 24 échantillons d’eau des puits de ce secteur collectés, en mars 2023. Il ressort de l’analyse des résultats que l’eau est fortement minéralisée, contaminée en cadmium, plomb et arsenic et présente de forts facteurs de contamination. Par ordre décroissant de facteur de contamination, on note 220 fois supérieur à la norme OMS pour l’arsenic ; 33,92 fois pour le plomb et 1,76 fois pour le cadmium. Le quotient de risque calculé est supérieur à 1 pour l’As, le Cd et le Pb chez l’adulte et l’enfant ainsi que pour le Cr chez l’enfant. L’ensemble de l’eau du puits collectée est contaminée. Cela pose donc un problème de santé publique. La sensibilisation du public aux effets des contaminants de l’eau et à la politique d’approvisionnement en eau potable et d’assainissement dans la zone doit être une priorité pour les autorités du pays.

Mots clés : eaux souterraines, contaminants, puits, eau, côte ouest, Kodjoviakopé

SEINO Richard Akwanjoh¹, ENDUM Lucas Akacha¹, NGYANYIYI Abdoul²

1. Laboratory of Genetic Toxicology & Orthopterology (LAGTO), Department of Zoology, Faculty of Science, The University of Bamenda, P.O. Box 39 Bambili- Bamenda, Cameroon.

• Applied Biology and Ecology Research Unit (URBEA), Department of Animal Biology,

Faculty of Science, University of Dschang. P.O. Box 57 Dschang, West Region, Cameroon.

ABSTRACT

Purpose:  In Cameroon, the African walnut Tetracarpidium conophorum is used in the traditional treatment of prostate cancer. The antimitotic activity of this nut is yet to be investigated. The purpose of this study is to evaluate the antimitotic activities of this African walnut Tetracarpidium conophorum since cancer is a disease of mitosis.

Methods: Five aqueous extracts of boiled nuts were used to investigate the antimitotic properties of Tetracarpidium conophorum by the Allium cepa assay. Percentage sprouting and growth of roots of treated A. cepa were measured and compared to the control which was water. Mitotic index, mitotic inhibition index and chromosomal abnormalities were determined on treatment of A. cepa bulbs with various aqueous concentrations of Tetracarpidium conophorum.

Statistical analysis: The Student’s t test and the SPSS 15.0 statistical package was use for the analysis.

Results: Aqueous extracts of Tetracarpidium conophorum inhibited root sprouting and growth in A. cepa. Inhibition was proportional to concentration of aqueous extract and was greater than 50% at 30% concentration of the extract. Chromosomal abnormalities recorded included bridges, laggards, ghost cells, chromosome fragments and Anaphase vagrants.

Conclusion: Our findings show cytotoxic and genotoxic effects of these concentrations of GA and indicate that the difference among control and treatment groups were statistically significant. Therefore, Tetracarpidium conophorum possesses antimitotic properties and henceis a potential anticancer agent that require further studies and development.

Key words: Tetracarpidium conophorum, Mitotic Index, Mitotic Inhibition, Chromosomal abnormalities, Allium cepa.  

SEINO Richard Akwanjoh^1&2, ENDUM Lucas AKACHA¹, NGYANYIYI Abdoul²

1. Laboratory for Genetic Toxicology & Orthopterology (LAGTO), Department of Zoology, Faculty of Science, The University of Bamenda, P.O. Box 39 Bambili- Bamenda, Cameroon.

• Applied Biology and Ecology Research Unit (URBEA), Department of Animal Biology, Faculty of Science, University of Dschang. P.O. Box 57 Dschang, West Region, Cameroon.

ABSTRACT

Background: Many bioactive substances in plants have the potentials to affect physiological processes in both plants and animals. One of the most common tests used in the evaluation of antimitotic and antiproliferation properties of plant extracts is the Allium cepa assay.

Aim:

This study was aimed to screen the seeds of P. nigrum, a common spice used in Cameroonian cuisines, for antiproliferative and antimitotic properties to and hence confirm their anticancer activity.

Materials and Methods:

Onion bulbs were treated to various concentration of the water extracts of dried seeds of P. nigrum for 72 hours. To determine the antiproliferative and antimitotic effects of the extracts, the onion bulbs were examined for sprouting of new roots, growth in length of the roots, mitotic indices and chromosomal abnormalities.

Results and conclusion:

The extracts were antiproliferative and antimitotic to the roots of A. cepa. The number of roots sprouted, the length of the roots and mitotic index (MI) significantly decreased with increase in concentration of the extract. Chromosomal aberrations such as chromosome bridges, chromosome laggards, chromosome stickiness and vagrants were recorded indicating the cytogenotoxic nature of the extracts.  

Key words: Antiproliferative, Antimitotic, water extract, P. nigrum seeds, allium cepa.

 Department of Chemistry and Chemical Engineering,  University of Malawi, Chirunga Road, Zomba, Malawi, University of MALAWI

Abstract

This study was carried out in the city of Zomba which happen to be the formal capita of Malawi. Three rivers where selected which are: Likangala, Mulunguzi and the Domasi river with each of the rivers having particular characteristics. The Likangala catchment is affected by increasing population which has resulted in urban sprawl. It also originates on Zomba Plateau and flows into Mulunguzi Dam which provides water to Zomba city. The Domasi River collect all the effluent from Domasi market and prison. Generally, 9 sampling stations were studied in 3 streams of the Zomba urban town and a total of 98 taxa were identified, in which 96 were identified to the species or generic level and 2 to the family level. These taxa belong to 3 phyla (Arthropods, Mollusca and Annelids), 4 classes (Crustaceans, Insects, Gastropods and Achaeta), 12 orders and 50 families. Arthropods are the most diversified with 2 classes, 9 orders, 49 families and 92 morphotypes. There are followed by Mollusca with a single class, order, family and 3 morphotyps. The Annelids has just a single family with 2 species. The class of Insects in the most represented with 90 morphotypes divided into 8 orders and 46 families. The Mollusca have 3 species in 2 families and 1 order while the Annelids showed 2 species in a single family. The class of crustaceans had just a single family and species. Of the 8 orders identified in the class of insects, that of Hemiptera is the most represented with 27 taxa and 11 families, it was followed by the Diptera (19 taxa and 7 families), Coleoptera (16 taxa in 7 families), Trichoptera (9 taxa and 9 families), Odonata (8 taxa and 5 families), Ephemeroptera (6 taxa and 5 families) and finally we have the Plecoptera and Aquatic Lepidoptera with just 1 taxon and family each.  

Key words: Biodiversity, macroinvertebrates, abiotic factors, three streams, Malawi.

Yede1*, Mahob² Raymond Joseph, Akama³ Pierre Dieudonné, Mbenoun Masse¹ Paul Serge, Mballa Ndzié¹ Paul Arnaud, Ibrahim¹ Housseinatou, Nkale Moukoudi Tonton1, Dimi Mvelé¹ Pierre, Messie Djegome¹ Mariam and Bilong Bilong² Charles Félix

¹Laboratory of Zoology, Department of Animal Biology and Physiology, University of Yaoundé I, P.O Box 812 Yaoundé-Cameroon; ²Laboratory of Parasitology and Ecology, Department of Animal Biology and Physiology, University of Yaoundé I, P.O Box 812, Yaoundé-Cameroon; ³Department of biological sciences, higher teacher training college, University of Yaoundé I, P.O Box 47 Yaoundé-Cameroon

Corresponding author E-mail: e * yede@facsciences-uy1.cm

Abstract

The knowledge of insect biodiversity in general, and heteropteran species in particular under field conditions, which are needed to optimize the preservation of the entomofauna diversity sensu lato, especially endangered species in one hand, and the protection of cocoa-based agroforestry systems against their main insect pests on the other hand. For this reason, we are characterized the community of Heteropterans and their ecological status in 12 cocoa farms of three localities (Bokito, Obala and Ngomedgzap) in the Centre Region of Cameroon, using the Chemical Knock Down Method, relevant dichotomous keys and reference insect collections for insect’s identification and diversity indices: H’ index of Shannon-Weaver, J Equitability index of Pielou and Is Similarity index of Sorensen in 2023. A total of 4904 individuals were collected in all the studied cocoa farms, divided into 137 Heteropteran species, 90 genera and 16 familles. This insect community belong to four ecological groups: 11 (8% in the total) specimens were recognized as cocoa insect pests, 8 (6%) as predators, 13 (9%) as unknown and 105 (74%) as opportunistic. Compared to other ecological groups, insect pests were more abundant with 2664 (54.33%) up to 4904 individuals, followed by unknown 1725(35.17%), opportunistic 483(9,85%), then 32(0.65%) were predators. The abundance of insect pest varied from 2019 (41.17%) individuals for Sahlbergella singularis (Miridae) to 1 (0.02%) individual for Haliomorpha annulicornis (Pentamidae).The current study provides valuable data regarding heteropteran species biodiversity under field conditions in order to optimize the preservation of the entomofauna diversity sensu lato, especially endangered species in one hand; and improve sustainability in the protection of cocoa-based agroforestry systems against their main insect pests via the integrated pest management (IPM) programs in order to increase the annual cocoa farms yield i.e. the cocoa farmers’ incomes on the other hand.

.

Keys words: Heteropteran biodiversity, ecological status, cocoa farms, Centre region of Cameroon, IPM

*ABONDO MATHIEU SERGE¹, MBOUOUMBUO MAMA^1,2, ACHA YANNICK ACHA¹, *Gideon A,A¹

¹Laboratory of Hydrobiology and Environment, Faculty of Sciences, University of Yaounde 1

²Institute of Water and Environnement, University of Ebolowa    *Corresponding author: abondoams70@gmail.com,Tel+237697583912; ajeagahg@yahoo.com, 237675916857.

ABSTRACT

With the aim of evaluating the physicochemical and biological quality of the waters of the Tongolo river, in the central region of Cameroon, a physicochemical analysis coupled with that of ciliated protozoa was carried out from April to September 2023. The samples were carried out on a monthly basis. The physicochemical parameters were measured following the recommendations of Rodier. Ciliates were sampled by the direct method in several multihabitats of the aquatic ecosystem. The physicochemical analyzes reveal that the waters studied have fairly good oxygenation (62.94 ± 25.76%), are neutral to basic (pH = 7.01 ± 0.46), poor in oxidizable organic matter (15.64 ± 11.02 mg/L), in nitrogen compounds (2.70 ± 2.20 mg/L of ammoniacal nitrogen; 3.37 ± 2.34 mg/L of nitrates; 1.66 ± 1.37 mg/L of nitrites) and very mineralized (conductivity = 163.22 ± 16.95 μs/cm) and colored (457.61 ± 59.66 Pt-Co), thus reflecting poor quality water. A total of 1769 ciliated individuals were identified and divided into 39 species, 3 classes, 8 orders and 21 families. Biological analyzes reveal a mesosaprobe to polysaprobe environment dominated by the Paramecidae and Vorticellidae families. 

 Keywords: Ciliated, Mesosaprobe, Polysaprobe, watercourse, Poor quality.

RESUME

Dans le but d’évaluer la qualité physicochimique et biologique des eaux du cours d’eau Tongolo, dans la région du centre du Cameroun, une analyse physicochimique couplée à celle des protozoaires ciliés a été menée d’avril à septembre 2023. Les prélèvements ont été réalisés suivant une fréquence mensuelle. Les paramètres physicochimiques ont été mesurés suivant les recommandations de Rodier. Les ciliés ont été échantillonnés par la méthode directe dans plusieurs multihabitats de l’écosystème aquatique. Les analyses physicochimiques révèlent que les eaux étudiées ont une assez bonne oxygénation (62,94 ± 25,76%), sont neutres à basiques (pH=7,01 ± 0,46), pauvres en matières organiques oxydables (15,64 ± 11,02 mg/L), en composés azotés (2,70 ± 2,20 mg/L d’azote ammoniacal ; 3,37 ± 2,34 mg/L de nitrates ; 1,66 ± 1,37 mg/L de nitrites) et très minéralisée (conductivité =163,22 ± 16,95 μs/cm) et colorées (457,61 ± 59,66 Pt-Co), traduisant ainsi les eaux de mauvaise qualité. Un total de 1769 individus ciliés a été identifié et réparti en 39 espèces, 3 classes, 8 ordres et 21 familles.Les analyses biologiques révèlent un milieu mésosaprobe à polysaprobe dominé par les familles des Paramecidae et des Vorticellidae. 

                Mots clés : Cilié, Mésosaprobe, Polysaprobe, cours d’eau, Mauvaise qualité.

* ABONDO MATHIEU SERGE¹, MBOUOUMBUO MAMA^1,2, ACHA YANNICK ACHA¹, *Gideon A,A¹

¹Laboratory of Hydrobiology and Environment, Faculty of Sciences, University of Yaounde 1

²Institute of Water and Environnement, University of Ebolowa *Corresponding author: abondoams70@gmail.com,Tel+237697583912; ajeagahg@yahoo.com, 237675916857.

RESUME

Dans le but de décrire les protozoaires ciliés dans les milieux tropicaux une analyse de ces infusoires a été menée d’avril à septembre 2023 à Yaoundé au Cameroun. Ces organismes, unicellulaires, présentent des formes très variées et se caractérisent, principalement, par de nombreux cils vibratiles locomoteurs qui définissent le phylum. Les Ciliés sont parmi les unicellulaires les plus complexes en structure, morphologie et en eco-physiologie. Les cils sont implantés sur les lignes appelées cinéties, tous les cils d’une cinetie battent l’un après l’autre provoquant la propulsion de la cellule. La cellule est polarisée, et les organites forment des zones spécialisées dans la nutrition, la motricité ou l’excrétion. Parmi ces espèces décrites, 17 appartiennent à la classe des Polyhyminephora, 12 à la classe des Kinetophragminophora et 10 à la classe des Oligohymenophora avec des abondances relatives respectives de 43%, 31% et 26%.

Mots clés : morphologie, Cilié, milieux aquatique, zone tropicale

ABSTRACT

With the aim of describing ciliated protozoa in tropical environments, an analysis of these infusoria was carried out from April to September 2023 in Yaoundé, Cameroon. These unicellular organisms have very varied shapes and are characterized, mainly, by numerous vibratile locomotor cilia which define the phylum. Ciliates are among the most complex unicellular organisms in structure, morphology and eco-physiology. The cilia are implanted on the lines called kinetias, all the cilia of a kinetia beat one after the other causing the propulsion of the cell. The cell is polarized, and the organelles form areas specialized in nutrition, motor skills or excretion. Among these species described, 17 belong to the class Polyhyminephora, 12 to the class Kinetophragminophora and 10 to the class Oligohymenophora with respective relative abundances of 43%, 31% and 26%.  

Keywords: morphology, Ciliate, aquatic environments, tropical zone

COMPARISON OF MORPHOLOGICAL PARAMETERS AND GERMINATION CAPACITY OF CASHEW NUTS (ANACARDIUM OCCIDENTALE L.) FROM THE FOUR PRODUCTION ZONES IN SENEGAL.

Khémes Marie Odile THIOCONE^1*, Mohamed Mahamoud CHARAHABIL¹, Etienne TENDENG², Diariatou NIANG² et Landing NDIAYE¹

¹ Université Assane Seck de Ziguinchor, Laboratoire d’Agroforesterie et d’Ecologie, BP 523, Ziguinchor, Sénégal

¹ Université Assane Seck de Ziguinchor, Laboratoire d’Agroforesterie et d’Ecologie, BP 523, Ziguinchor, Sénégal

²Université Cheikh Anta Diop de Dakar, Laboratoire de Production et de Protection intégrées en Agroécosystèmes, BP 5005, Dakar, Sénégal

²Université Cheikh Anta Diop de Dakar, Laboratoire Commun de Microbiologie des sols, BP 1386, Dakar, Sénégal

¹ Université Assane Seck de Ziguinchor, Laboratoire d’Agroforesterie et d’Ecologie, BP 523, Ziguinchor, Sénégal

*Auteur correspondant, E-mail : k.thiocone5328@zig.univ.sn, Téléphone : +221773863152

 Abstract

     The current challenge of the cashew sector in Senegal is essentially linked to productivity. To do this, germination capacity is one of the important steps to master to assess the quality of seeds. This study aims to evaluate the relationship between the morphological parameters of nuts and their germination capacity. A batch of 250 cashew nuts was taken from the four production zones of Senegal. Measurements of length, width, thickness and weight of the nuts were taken. The aril up mode was used for sowing. Thirty days after sowing, germination rate, speed and time were evaluated. The results obtained show that nuts from Fatick presented the best morphological parameters and those from Kolda the lowest values. The shortest germination speed was obtained with the Kolda provenance (3rd day after sowing) with 65.85% of germinated nuts and the longest speed with the Fatick nuts (7th day after sowing) with 53.33%. sprouted nuts. The germination time was 15 days for nuts from Fatick, Ziguinchor, and Kolda and 17 days for nuts from Sédhiou. The best germination rate was recorded by the Ziguinchor provenance (64.62%) and the lowest by the Fatick provenance (23.08%). The results of this study constitute a decision-making tool for producers on the choice of cashew seeds.

Keywords: Parameter, Morphological, Origin, Germination, Cashew tree

Résumé

Le défi actuel de la filière anacarde au Sénégal, est essentiellement lié à la productivité. Pour se faire, la capacité germinative est une des étapes importantes à maitriser pour évaluer la qualité des semences. Cette étude a pour objectif d’évaluer la relation entre les paramètres morphologiques des noix et leur capacité de germination. Un lot de 250 noix de cajou a été prélevé dans les quatre zones de production du Sénégal. Des mesures de longueur, de largeur, d’épaisseur et de poids des noix ont été effectués. Le mode arille vers le haut a été utilisé pour le semis. Trente jours après semi, le taux, la vitesse et le délai de germination ont été évalués. Les résultats obtenus montrent que les noix en provenance de Fatick ont présenté les meilleurs paramètres morphologiques et celles de Kolda les plus faibles valeurs. La plus courte vitesse de germination a été obtenue avec la provenance Kolda (3 e jour après semis) avec 65,85% de noix germées et la plus longue vitesse avec les noix de Fatick (7 e jour après semis) avec 53,33 % de noix germées. Le délai de germination était de 15 jours pour les noix en provenance de Fatick, Ziguinchor, et Kolda et 17 jours pour les noix en provenance de Sédhiou. Le meilleur taux de germination a été enregistré par la provenance Ziguinchor (64,62%) et le plus par faible par la provenance Fatick (23,08 %). Les résultats de cette étude constituent un outil d’aide à la décision pour les producteurs sur le choix des semences d’anacarde. 

Mots clés : Paramètre, Morphologique, Provenance, Germination, Anacardier

Baleba^1,2 Laurent Justinien, Moumbagna Mboutngam³ Mouhamadou, Mahot¹ Hermine Claudine, Essono³ Damien Marie, Beyegue-Djonko¹ Honoré, Koga Mang’Dobara³, Nkobe Keghe¹ Martin, Ngansop⁴ Eric, Mvondo Awono² Jean Pierre, and Mahob^3* Raymond Joseph

¹Institute of Agricultural Research for Development (IRAD), P.O Box 2067, Yaoundé, Cameroon, ² Department of Crop Sciences, University of Dschang, P.O Box 222, Dschang, Cameroon, ³Faculty of Science, University of Yaoundé I, P.O Box 812, Yaoundé, Cameroon, ⁴National Herbarium of Cameroon (HNC), IRAD, P.O Box 1601, Yaoundé

*Corresponding author E-mail: raymondmahob@gmail.com; Tel.: (+237) 679 18 76 46/695 92 62 00

Abstract

The study aimed to assess the biodiversity, ecological status and farmers’ use/perception of non-coffee plants species (NCPS) in contrasting locations, due to the lack of these valuable data regardless of agroecological services and/or environmental conservation. Thus, investigations through the transverse study have been carried out within 17 Robusta coffee plantations, 7 villages and 3 sub-divisions of Noun Division. NCPS were identified using relevant dichotomous keys whereas their recovery rate was estimated via Braun-Blanquet method. Biodiversity of NCPS was estimated using the specific richness and/or diversity indices while their ecological status and farmers’ use/perception were determined through Dajoz (1982) modified method and structured questionnaires respectively. In total, 48 NCPS divided into 38 genera and 17 families were inventoried. Elaeis guineensis revealed most frequent species, with 30.85% of occurrence while Albizia adianthifolia, A. glaberrima, Antidesma laciniatum, Citrus medica, C. sinensis, Erythrophleum suaveolens, Ficus mucuso, F. polita, F. umbellata, Macaranga sp., Mangifera foetida, Piptadeniastrum africana, Pterocarpus erinaceus, P. milbraedii, Pycnanthus angolensis, Sarcocephalus diderrichii, Sterculia tragacantha, Trilepisium madagascariense and Voacanga africana, were found scarce, with 0.25% of occurrence each. NCPS circumference and recovery rate varied significantly (p<5%) between the studied plots, from 64.75 ± 3.17 to 181.86 ± 43.81 cm and 8% to 100% respectively. Plants abundance and specific richness/diversity also varied between plots, villages and sub-divisions, with respective values of 2 to 44 individuals, 28 to 117 and 91 to 177 (for abundance) versus 0.00 to 3.34, 0.57 to 5.04 and 0.58 to 7.54 (for specific richness/diversity). 66.66% of inventoried NCPS were abundant and 33.34% were extremely rare. According to the respondents, NCPS have different status/functions: 89.47%, 34.21%, 23.68 and 7.89% serve as shade trees, timber, therapeutic purposes/food, and soil enrichment respectively. Our findings revealed the need to take appropriate measures to preserve endangered species for sustainability environmental conservation of the studied agrosystems.

Keywords: Specific richness/diversity, associated perennial trees, Robusta Coffee Agrosystems, environmental conservation, ecosystem services

Biological and physicochemical characterization of wastewater in an anthropogenic zone          

Asi Quiggle Atud^[1]*, Zoua  Vincent de Paul ^[1],  Visiy Edna Buhnyuy ^[1]

^[1] Ecole Nationale Supérieure des Travaux Publics, BP 510, Département de Génie de l’Environnement, Yaoundé Cameroun

       * Correspondance: asiatud@yahoo.com                                                                      

             ORCID iD: 0000-0002-2658-3684

Résume

Dans le but d’évaluer le devenir des parasites lors du cycle de traitement des eaux usées, les échantillons ont été prélevés à l’entrée et à la sortie dans deux stations de traitement des eaux usées. Les analyses physicochimiques et le taux d’abattement ont été réalisés par les méthodes standards. Les analyses biologiques ont été réalisées par les techniques de sédimentation, Ziehl-Neelsen modifiée et les Trichrome de Weber. Les résultats montrent que les taux d’abattement de la Matière organique (77.18%), de la  DBO₅ (99.33%) et  MES (95.72%) sont relativement élevés. Alors que les valeurs de  l’oxygène dissous et la résistivité indicateurs de la qualité des eaux sont élevés au niveau des stations de sortie. L’analyse parasitologique de ces eaux usées a montré que, ces eaux contiennent plusieurs types de parasites caractérisées par une diversité de formes et d’espèces notamment les formes des oocystes, des kystes et des spores de Protozoaires ( Cryptosporidium spp., Entamoeba histolytica, Giardia intestinalis, Microsporidium…) ainsi que des œufs et des larves d’ Helminthes pathogènes (Ascaris sp., Hymenolepis nana, Trongyloides sp…). L’abattement des spores, oocystes, kystes, œufs et larves sont respectivement croisant de 53 %, 76 %, 80 %, 100 % et 100 %. Le taux d’élimination d’Helminthes plus important, serait lie à la sédimentation et pouvoir de résistance faible contrairement  aux Protozoaires de petite taille et plus résistants. Ces résultats démontrent des améliorations des qualités physicochimiques et biologiques des organismes de grandes tailles à la sortie avec une meilleure performance à la station de Messa.  L’efficacité de ces centres d’épuration des eaux usées serait d’avantage plus optimisée  en associant une station tertiaire pour désinfection des parasites  de forte capacité de résistance qui échappent les mailles de traitement secondaire. Cette étude ressort en plus, l’intérêt d’intégrer les spores microsporidiennes plus résistantes, caractéristiques de bio indicateur pour l’évaluation et le contrôle de la qualité d’eau  en conformité avec les normes des rejets des eaux usées.

Mots clés Eaux usées domestiques. Parasites. Taux d’abattement. Physicochimie. Eaux épurées. Station d’épuration. Yaoundé

Abstract

In order to assess the fate of parasites and the effectiveness of wastewater treatment, samples were taken at the inlet and outlet of two wastewater treatment technology. The physicochemical analysis and the abatement rate were carried out using standard methods. Biological analysis were carried out using sedimentation, modified Ziehl-Neelsen and Weber Trichrome technique. The results show that the abatement rates of Organic Matter (77.18%), BOD₅ (90.33%) and suspended solids (95.72%) are relatively high. While the dissolved oxygen values and resistivity, indicators of water quality, are high at the outlet stations.  The parasitological analysis of this wastewater has shown that this water contains several types of parasites characterized by a diversity of forms and species, including the forms of oocysts, cysts and spores of Protozoa ( Cryptosporidium spp., Entamoeba histolytica, Giardia intestinalis, Microsporidium, etc.). as well as eggs and larvae of pathogenic Helminths (Ascaris sp., Hymenolepis nana, Trongyloides sp….). The reduction of spores, oocysts, cysts, eggs and larvae is 53%, 76%, 80%, 100% and 100% respectively. The Helminth Elimination Rate more important, would be linked to sedimentation and weak resistance power unlike the small size of  Protozoa that is  more resistant. These results demonstrate improvements in the physicochemical and biological qualities of large organisms at the outlet with a better performance at the Messa station.  The efficiency of these wastewater treatment technologies would be further optimised by combining a tertiary station for disinfection of parasites with a high resistance capacity that escapes the secondary treatment meshes. This study also highlights the interest of integrating microsporidian spores, more resistant and characteristics of bio indicator for the evaluation and control of water quality in accordance with wastewater discharge standards.

Keywords  Domestic wastewater. Parasites. abatement rate.  Physicochemical parameters. Purified water. Wastewater treatment technology. Yaounde