Bioconversion of filter mud using vermicomposting employing two exotic and one local earthworm species Meena Khwairakpam a, * , Renu Bhargava b a Department of Civil Engineering, Malviya National Institute of Technology (MNIT), Jaipur 302017, India b Department of Civil Engineering, Indian Institute of Technology Roorkee (IITR), Roorkee 247667, India article info Article history: Received 19 March 2009 Received in revised form 9 June 2009 Accepted 12 June 2009 Available online 15 July 2009 Keywords: Filter mud Vermicomposting Eisenia fetida Eudrilus eugeniae Perionyx excavatus abstract Three different earthworm species Eisenia fetida, Eudrilus eugeniae and Perionyx excavatus in individual (Monocultures) and combinations (Polycultures) were utilized to compare the suitability of worm species for vermicomposting of filter mud as well as the quality of the end product. The filter mud blended with saw dust can be directly converted into good quality fertilizer (vermicompost). Eight different reactors including three monocultures and four polycultures of E. fetida, E. eugeniae and P. excavatus and one con- trol were used for the experiment. Vermicomposting resulted in significant reduction in C/N ratio, pH, total organic matter (TOC) but increase in electrical conductivity (EC), total nitrogen (TN), total phospho- rus (TP) and macronutrients (K, Ca and Na). Oxygen uptake rate (OUR) dropped up to 1.64–1.95 mg/g (volatile solids) VS/day for monoculture reactors and 1.45–1.78 mg/g VS/day for polycultures reactors, respectively, after 45 days of vermicomposting. Cocoon production and the earthworm biomass increased as vermicomposting progressed. On an overall the mono as well as polyculture reactors pro- duced high quality stable compost free from pathogens and no specific differentiation could be inferred between the reactors. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction The present society, with its high population densities, heavy industrialization and intensive methods of agriculture produces ever increasing quantities of solid wastes. One of the industries that generate large quantities of recyclable organic materials is the sugarcane industry. Sugar is mainly manufactured from sugar- cane and beetroot. In India, sugarcane is the key raw material for the production of sugar. India is the second largest sugar producer in the world (after Brazil), accounting for around 10–12% of world’s sugar production (ICRA, 2006). According to the Indian Directorate of Economics and Statistics, India produces on average 270 million tones of sugar cane per year and it is one of the most polluting industries. Sugarcane industry generates huge quantity of residue after the sugarcane juice has been clarified commonly known as fil- ter mud. For about 134 million tones of sugarcane crushed, 4.0 mil- lion tones of filter mud are generated (Yadav, 1995). There is a major disposal problem for the filter mud although it is fairly rich in organic nutrients; it finds little use as agricultural fertilizer. The primary reason for this is the insoluble and imbalanced nature of the nutrient content in it. It generates intense heat (65 °C), foul odor and takes long time for natural decomposition (Sen and Chan- dra, 2006). Disposal of this waste is becoming one of the major areas of concern for a developing country like India. Currently, a very mea- ger quantity of the filter mud is usually used as fertilizer source and soil conditioner, or it is returned to cane fields. However, this approach is not desirable practice in view of the odor from biolog- ical degradation (Tsai et al., 2003). Available literature has proved that application of un-decomposed wastes or non-stabilized compost to land may lead to immobilization of plant nutrients and cause phytotoxicity (Butler et al., 2001). Several technologies are harnessed to deal with the organics that have the potential to pollute the environment. Existing technologies concentrate to oxidize the organics in the waste pro- ducing a new stream that has its own disposal problems. The need of the hour is to develop close loop technologies which harness the renewable energy and/or nutrient of these waste organics to fuel/ or amend the soil. Vermitechnology can be one of the appropriate techniques for the safe treatment and reuse of non-toxic filter mud by natural biodegradation. Filter mud is an ideal substrate for worms for bioconversion into fertilizer because of its fine particle size and presence of microbes. Vermitechnology application also helps in cost effective and efficient recycling of animal wastes, agricultural residues and industrial wastes. Several epigeics (Eisenia fetida, Eisenia andrei, Eudrilus eugeniae, Perionyx excavatus and Perionyx sansibaricus) have been identified as potential candidates to decompose organic waste materials (Suthar, 2007a). Some attempts have been made to biodegrade a variety of materials using vermitechnology 0960-8524/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.biortech.2009.06.038 * Corresponding author. Tel.: +91 141 2713121; fax: +91 141 2529062. E-mail address: meena.kh@gmail.com (M. Khwairakpam). Bioresource Technology 100 (2009) 5846–5852 Contents lists available at ScienceDirect Bioresource Technology journal homepage: www.elsevier.com/locate/biortech