Speaker: Prajakta Pratap Patil
The main objective of the study was to safely manage faecal sludge for pathogen removal. Two different methods, vermicomposting and lactic acid fermentation was used to achieve complete pathogen removal. The number of activated Helminth eggs and bacterial pathogens along with the physicochemical parameters were analyzed at every step of the experiment. The relation between pathogen reduction, physicochemical parameters and time was studied to get the best quality final product. The study utilized a combination of different waste products giving a valuable agricultural fertilizer limiting the health risk to users.
Introduction: Composting is perceived to be the most promising among the various biological treatment methods for faecal sludge management since it is cheaper, tolerates fluctuations in the composition of organic matter and produces more stable organic fertilizers (Costa et al.,2016). While composting allows the destruction of pathogens and the removal of toxic compounds, vermicomposting reduces particle size and increases the availability of nutrients (Ndegwa and Thompson, 2001). Despite the benefits of the method, there is widespread reporting of regrowth and recontamination of pathogens in compost, which are composting challenges (Wilkinson, K.G., 2007). Among the other pathogen’s helminths are the most important because literature data indicate that helminth eggs can survive in tropical climates for 10–12 months. (Larsen and Roepstorff, 1999; Sangui-netti et al., 2005). Vermicomposting is known to significantly reduce the pathogen content (Valdez-Perez et al., 2011). In this study two different methods of vermicomposting have been studied and compared for their pathogen removal efficiency.
Methods: Ten tanks were set up each of 1 m3 capacity to collect septage from honeysucker (8000L). The solids and liquids were allowed to separate by leaving the set up undisturbed for 24 hours. The separated liquid was treated using two stage vertical flow constructed wetland. The solids were treated by vermicomposting process using two different methods. In the first method the dewatered faecal sludge was mixed with sugarcane press mud in 2:1 ratio followed by vermicomposting up to 40 days. and in the second procedure, lactic acid fermentation of faecal sludge and sugarcane press mud was done using lactic acid bacteria followed by vermicomposting. The pathogen assessment included Helminth eggs viability (Ascaris lumbricoides and Trichuris trichiura) and detection of bacterial pathogens (Total coliform, Faecal coliform, E.coli, Pseudomonas sp., Salmonella sp., and Shigella sp.) along with the physicochemical parameters, (Moisture, temperature, pH, conductivity, particle size, bulk density, total carbon, total nitrogen, total phosphorous, total potassium, and heavy metal analysis). These analyses were done at every step of the experiment, helminth eggs viability was checked microscopically and bacterial pathogens were detected using agar spread plate method.
Results and discussion: Most of the values of physicochemical parameter of compost were according to FCO guidelines. The liquid treated using constructed wetland showed good results. The pathogen analysis is an ongoing experiment. so far, we have got results of our trial experiment which included 15 days fermentation and 20 days vermicomposting. We observed reduction in the bacterial pathogens after the lactic acid fermentation and composting. Number of viable Helminth eggs were also reduced but total inactivation was not achieved. In the ongoing experiments we have increased the composting time expecting the complete inactivation of helminths eggs as well as bacterial pathogen reduction. Comparison of two methods will be done to check if the fermentation is necessary or vermicomposting alone can achieve complete pathogen removal, this will allow to reduce the overall time of the composting. The relationship study between physicochemical parameters and pathogen removal is also included to understand the quality of final compost.
This research focuses on the disease prevention, caused by Helminth eggs due to application of poorly treated faecal sludge in the agricultural fields. Vermicomposting along with lactic acid fermentation will safely manage the faecal sludge ensuring the complete inactivation of Helminth eggs as well as other bacterial pathogens. Quality of the final compost will be assured by the analysis of physicochemical parameters along with the pathogen analysis. This study utilizes the wastes (faecal sludge and sugarcane press mud) in ecofriendly and cost-effective way limiting the health risk to users.