STUDY ON CHARACTERISTICS OF AEROBIC MICROBIAL FLOC IN OUTDOOR LINED POND

The aerobic microbial floc (AMF) characteristics such as size, settling velocity, volume, density index and porosity directly or indirectly determines the structure, nature and quality of floc. The characteristics of floc highly influenced by physiochemical parameters of culture water. The fertilizers used, particularly the carbon source is responsible for floc composition and nutrient profile. Spent wash is the cheapest best carbon source which acts as substratum for floc development. Basic understanding on the floc characteristics has not been reported systematically, the present study was carried out to develop in depth knowledge on the characteristic of floc developed using the spent wash in order to understand its beneficiary effects.

The experiment was conducted in outdoor lined pond (100 ton capacity) in duplicate. The aerobic microbial floc was developed using spent wash as carbon source by following Dr. Nyan Taw protocol with minor modification.  Culture ponds were facilitated with aspirator aerator to keep the floc in suspension.

The four week study was conducted and the quality of floc was assessed by the  parameters such as floc volume, floc volume index (FVI), floc density index (FDI), floc size, structure, settling velocity, porosity, total suspended solids (TSS), volatile suspended solids (VSS) and total organic carbon (TOC) as per standard protocol. The floc characteristics were analyzed at 6 days interval. The floc volume was found to be increased from         13 ± 0.6 to 43 ± 1.5 ml/l in aerobic microbial floc system (figure 1). The floc volume positively influenced the total suspended solids and volatile suspended solids. The mixed intensity have connection with floc size which is correlated with physics settling velocity and nature of porosity. The floc structure was irregular in shape with smaller size in initial period as young floc and larger size in final period as matured floc. The proximate composition of aerobic microbial floc revealed the status of available nutrients. The protein content (16.61 ± 0.02%) was found in the developed AMF which can be useful to balance the low protein feed with high nutrition. This study paves keystone to understand the characteristics of aerobic microbial floc.