Design and operation of nitrifying trickling filters in recirculating aquaculture: A review

The Nitrification Capacity of Different Types of Biological Filters An Overview

“…Trickling Filter A common biofilter type is the trickling filter due to its simplicity and non-mechanical nature. The main advantages of trickling filters compared to other filter types applied in aquaculture are: high process stability due to constant high oxygen levels; CO2 removal by degassing; water cooling in summertime; and simplicity of design, construction, operation and management [19]. While, the main disadvantages of trickling filters are: the relatively low volumetric removal rates (with consequently large sized biofilters); biofilm shedding; and risk of clogging when not properly designed and operated.…”

Experimental Study on Maize Cob Trickling Filter-Based Wastewater Treatment System: Design, Development, and Performance Evaluation

“…After the development of biofilm growth on maize cobs, the developed MCTF-WWT system was operated at constant hydraulic loading rate (HLR) of 113±2m /day in order to flush out the possible solids accumulated in the media. The removal efficiencies (η) were calculated using the following relationship [15,27,33]: (1) …where C in [mg/l] and C out [mg/l] are the influent and effluent concentrations, respectively.…”

“…Most of these materials (e.g., plastic, geotextiles, commercial rings, polyurethane foam, tire-derived rubber, sponge, biochar chips, and ceramics) are being prepared synthetically and cannot work without introducing specific seeding/ acclimatization of the microbial community. It would eventually increase operational costs of the treatment system [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. Moreover, technically trained human power is required to operate the treatment systems and also not easily available by the small landholder farmers.…”

“…It contains microorganisms for the biodegradation of the substrates to remove these substrates from the wastewater. The microbial community contains aerobic and facultative bacteria, fungi, algae, and protozoans [14][15]. Many factors affect the aerobic zone of the biofilm such as organic substrate, oxygen concentration, temperature, ventilation, wastewater pH, and characteristics of filter media including size, depth, weight, specific surface area, and void ratio, etc.…”

“…Effective media plays a key role in the development of microbial community/biofilm. Several biofilm support media have been used to increase the performance of a trickling filter, such as rocks/plastic [14], a nylon pot scrubber [18], commercial rings (e.g., crushed leca, kaldnes, and Norton), calcitic gravel [15][16], luffa cylindrical [19], geotextile [20], pall rings [21], polyurethane foam pores [22], coal cinder [23], tire-derived drubber [24], oyster shell [25], corrugated plastic sheet [26], stone [27], gravel and zeolite [28], sponge [29], zeolite and ceramsite [30], polypropylene plastic [31], biochar chips [32], and ceramic particles [33]. These are either costly or not easily available by small landholder farmers.…”