Etude comparative des performances des plateformes de compostage de Siteu et de Ngui Ã Dschang (Cameroun)
Authors: Laure Ngahane Emilienne , JoÃ«l Sagne MoubÃ© , Paulin Nana 
Published: June 2021

A Dschang, le compostage artisanal est le mode de traitement de la fraction fermentescible majoritaire dans les dÃ©chets locaux. QualifiÃ© dâ€™activitÃ© Ã haute intensitÃ© de main dâ€™Å“uvre (HIMO), il permet de crÃ©er trois emplois directs par tonne/jour de dÃ©chets traitÃ©s. Les deux plateformes fonctionnelles de nos jours Ã Dschang occupent une quarantaine de personnes et permettent de traiter en moyenne 3 000 tonnes de dÃ©chets chaque annÃ©e. Afin dâ€™entrevoir leur autonomie, les Ã©quipes ont Ã©tÃ© Ã©valuÃ©es par la mÃ©thode du bilan main dâ€™Å“uvre. Cette mÃ©thode est pratique et permet dâ€™exprimer la productivitÃ© des agents afin dâ€™Ã©valuer le coÃ»t de production et dâ€™identifier les leviers dâ€™optimisation. En ce sens, lâ€™augmentation des quantitÃ©s de dÃ©chets traitÃ©s par agent afin de diminuer le coÃ»t de production et lâ€™amÃ©lioration de la qualitÃ© de compost produit afin de faciliter son utilisation ont Ã©tÃ© identifiÃ©es comme les leviers internes. Cependant, sâ€™il est aisÃ©ment admis que la qualitÃ© obtenue est surtout conditionnÃ©e par la nature des dÃ©chets initiaux ; la quantitÃ© obtenue lâ€™est tout aussi. En effet, lâ€™Ã©tape de tri ainsi que lâ€™Ã©tape dâ€™affinage (criblage), nÃ©cessaires pour lâ€™obtention dâ€™un compost de qualitÃ©, reprÃ©sentent aussi les Ã©tapes les plus chronophages et qui dÃ©terminent objectivement leur productivitÃ©. A Dschang, ces deux Ã©tapes reprÃ©sentent en moyenne 84% (66% pour le tri et 18% pour le criblage) du temps de travail. Les performances de compostage mesurÃ©es diffÃ¨rent de 22% en faveur de Ngui oÃ¹ la productivitÃ© se situe Ã 10,41 ttraitÃ©es/homme.mois tandis quâ€™elle se situe Ã 8,53 ttraitÃ©es/homme.mois Ã Siteu. Les facteurs majeurs justifiant ces variations sont la qualitÃ© des dÃ©chets entrants (Ã 46,2%) et lâ€™amÃ©nagement des sites (Ã 34,3%). Aussi, quelques retours nÃ©gatifs, liÃ©s Ã la prÃ©sence dâ€™indÃ©sirables, ont Ã©tÃ© enregistrÃ©s auprÃ¨s des utilisateurs du compost produit Ã Siteu. Donc, du fait de la meilleure qualitÃ© des dÃ©chets entrants et de la concentration des activitÃ©s sur un espace limitÃ© Ã Ngui par rapport Ã Siteu, la consolidation des emplois crÃ©Ã©s et la pÃ©rennisation de lâ€™activitÃ© de compostage seraient assurÃ©es sur le site de Ngui car il a Ã©tÃ© Ã©tabli que ces derniÃ¨res passeraient, entre autres, par lâ€™atteinte dâ€™une productivitÃ© minimale de 10 ttraitÃ©es/homme.mois. Ceci renforce lâ€™argument de dÃ©velopper le compostage de proximitÃ© (au plus prÃ¨s de la production des dÃ©chets) et questionne sur la construction de grands sites.

Artisanal composting is the method of treating the wasteâ€™s fermentable fraction in Dschang. Qualified as a high intensity workforce, it provides three direct jobs per ton of daily treated waste. Around 40 people work in the two nowadays operational platforms and treat an average of 3,000 ton of waste each year. To foresee their autonomy, the guarantee of the sustainability of activities and consolidation of these jobs, the teams were assessed using the workforce assessment method. Itâ€™s a practical method for expressing the productivity of workers to express the cost of production and identify optimization levers. In this vein, the increase in the quantities of waste treated per agent in order to reduce the production cost and the improvement of the quality of the compost produced in order to facilitate its use have been identified as the internal levers. However, if it is readily accepted that the quality of compost is mainly conditioned by the nature of the initial waste; so is the quantity of compost obtained. In fact, the sorting stage as well as the screening stage, necessary to obtain good quality compost, also represent the most time-consuming stages and which objectively determine the workerâ€™s productivity. In Dschang, these two stages represent 84% (66% for sorting and 18% for screening). Nguiâ€™s team with a monthly productivity of 10.41 ton of waste treated/person performs 22% more than Siteuâ€™s team with a monthly productivity of 8.53 ton of waste treated/person. The major factors justifying these variations are the quality of incoming waste (at 46.2%) and site development (at 34.3%). Some negative feedback due to the presence of unwanted items were also recorded among users of the compost produced in Siteu. Therefore, due to the better quality of incoming waste and the concentration of activities on a limited space on the Ngui platform compared to that of Siteu, the consolidation of the jobs created and the sustainability of the composting activity would be ensured at Ngui. It was established that continuation of activities would require, among other things, the achievement of a minimum monthly productivity of 10 ton of waste treated/person. This strengthens the argument for developing local composting (as close as possible to waste production) and raises questions about the construction of large sites.vvvv