Dr Thuy Doan1, Bs. Minh Do2, Dr. Huong Mai2, Dr. Pascal Jouquet3, Dr. Jean-Luc Meaght1,3
1Soils And Fertilizers Research Institute, Ha Noi, Viet Nam, 2France- VietNam university (USTH), Cau Giay, Việt Nam, 3Institute of the Research for Development (IRD), Northern Tu Liem, Việt Nam
The latest innovation in waste management, Vermifiltration technology, which uses epigeic earthworms as an environmentally friendly and economical wastewater treatment technique, was almost unknown in developing countries, particularly in South East Asia. Viet Nam has a rapidly growing pig farming industry. However, the majority of the country’s pig raising (75-80%) is done in small farms, which lack the appropriate swine wastewater management to control the level of pathogen, odor and loss of nutrients in nutrient flows. This study aims to (i) optimize the parameters for the effectiveness of local organic flow vermifilter (wood-chip, sand, biohar and graviety ) in removing swine effluents ; (ii)to manipulate the understanding of hydraulic retention time to minimize the clogging of organic loads and maximize the earthworm population’s ability to transform them.
The experiment used 15 mesocosms of around 50 L, which were inoculated by the 50 adults.mesocosm-1 from mixed earthworm species (Adrei Eseinia and Pyrnovax Excavatus). It also used wastewater from swine house which was diluted by 20 times. Over the course of one month, this diluted wastewater was hand-irrigated to the mesocosms in a cycle of five different volumes as the 5 treatments: 3, 5, 7, 9, and 11 liters. day-1. This cycle was repeated three times throughout this month. The results showed, that the wastewater with high chemical properties (pH: 7.3., TSS, COD, BOD5, Pb, As: 162077, 178, 65 and 9 mg.l-1 ; Total contents of N,P,K: 348, 20 and 0.8 %; Coliform bacteria: 533 MNP.100ml-1, respectively ) was reached a removal efficiency of around 88-99% for TSS, total N,P, Pb and coliform bacteria; 28-62% for COD and total K ; 11-27% of As and 4-10% of pH for all level volumes. Mature vermicast with a C: N ratio of 19-25 was obtained when irrigated 5, 7litters.day-1. The application of these volumes of wastewaters on a vermifilter bed, with a 24-minute hydraulic retention time, led to an increase in the number of live and functioning earthworms. This experiment indicates that the Vermifilter system has potential to fundamentally change chemico-biological approaches towards water quality and earthworm development.
I have 22 years research experience in bio-technology, agronomy and soil ecology. I spent 12 years working on improve the quality of crop production via using the Biotechnology (in vitro propagation and molecular technique). I have 10 years studying the effect of organic amendment like compost, vermicompost and biochar on plant growth, soil and water quality. Since 2008, my work as part of the activities in the MSEC (Multi scale Environmental Change management – M tropic program) and LMI LUSES project: dynamic of Land Use changes and Soil Ecosystem Service, fundamental findings were the understanding of the ecological concepts. These concepts and theories are now required for the design of agronomical systems with cross cutting knowledge on soil and water science, agronomy, biodiversity. In this study, several functions or properties impacted by organic fertilization were considered: (i) soil chemical quality, (ii) soil macro fauna and soil microbial diversity, (ii) plant growth and yield, and (iv) water quality. At regional scale, the ecological concepts have been applied for designing experiment in Laos, Thai land and India. Furthermore, the extension of an economical and friendly vermicomposting process has also been trained to Farmers in Viet Nam via the NGO’s program