Comparison of the Nitrification Efficiencies of Three Biofilter Media in a Freshwater System

Transcription

1 Originl Artile Fish Aqut Si 4(4), , 2 Comprison of the Nitrifition Effiienies of Three Biofilter Medi in Freshwter System Diky Hrwnto,2, Sung-Yong Oh 3 nd Je-Yoon Jo,4 * Deprtment of Fisheries Biology, Pukyong Ntionl University, Busn , Kore 2 Deprtment of Fisheries nd Mrine Siene, Diponegoro University, Semrng 5275, Indonesi 3 Mrine Biology nd Living Resoures Reserh Deprtment, Kore Oen Reserh nd Development Institute, Seoul 425-6, Kore 4 Tinjin Agriulturl University, No. 22, Jinjing Rod, Xiqing Distrit Tinjin, 3384, P.R. Chin Astrt Totl mmoni nitrogen (TAN) removl effiienies of snd filter (), polystyrene miroed filter (), nd Kldnes ed filter () medi were evluted under mmoni loding rtes of 5, 25, nd 5 g m -3 dy -. The volume of eh filter medi tested ws 7 L, nd the wter flow rte for ll filter medi ws 24 L/min. The speifi surfe res of the,, nd were 7,836, 3,287, nd 5 m 2 /m 3, respetively. Snd ws fluidized nd the other two medi were trikle filtered. The volumetri TAN removl rte inresed with inresing mmoni loding rte for ll filter medi. Men volumetri TAN removl rtes under the mmoni loding rtes of 5, 25, nd 5 g m -3 dy - in (39.3, 68.6, nd g m -3 dy -, respetively) were higher thn those in (35., 57.4, nd 3.5 g m -3 dy -, respetively) nd (32., 42.5, nd 288. g m -3 dy -, respetively). These results were relted to differenes in the speifi surfe res of the filter medi. ws the most eonomi medi for effiiently removing TAN. Key words: Reirultion system, Biofilter medi, Nitrifition, Freshwter, Ammoni removl Introdution Mny studies hve een onduted to otin iofilter performne dt for mintining good wter qulity in reirulting system. Eh type of iofilter hs dvntges nd disdvntges (Wheton et l., 994). Although vrious types of iofilter medi re in use, efforts to identify the most effetive, eonomi, nd effiient medi re ongoing. Snd (Wheton et l., 994; Shnel et l., 22; Summerfelt, 26), polystyrene miroeds (Greiner nd Timmons, 998; Mlone nd Beeher, 2; Mlone nd Pfeiffer, 26; Timmons et l., 26), nd rtifiil plsti (Eikerokk, 99; Eikerokk nd Ulgenes, 998; Rusten et l., 26) hve eome importnt iofilter medi. Limited dt re ville out iofilter nitrifition performne nd mintining wter qulity onsidering totl medi volume. Medi volume eomes importnt when onsidering the speifi surfe re (SSA) nd iofilter spe (Wheton et l., 994; Lekng nd Kleppe, 2). Medi with different SSAs produe different surfe res in the sme volume. Medi with lower SSA require higher volume nd iofilter spe to otin the sme surfe re s medi with high SSA. Hene, omprison of the performnes of different iofilter medi t the sme volume is needed. Snd is the most well-known nturl medi nd hs een used suessfully (Wheton et l., 994, Losordo et l., 998; Shnel et l., 22; Summerfelt, 26). Among rtifiil medi, polystyrene hs widespred ommeril use (Greinner nd Timmons, 998; Mlone nd Beeher, 2; Mlone nd Pfeiffer, 26; Timmons et l., 26), nd Kldnes medium is reently developed rtifiil plsti medium (Lekng nd Kleppe, 2; Rusten et l., 26). The ojetive of this study Open Aess This is n Open Aess rtile distriuted under the terms of the Cretive Commons Attriution Non-Commeril Liense ( org/lienses/y-n/3./) whih permits unrestrited non-ommeril use, distriution, nd reprodution in ny medium, provided the originl work is properly ited. pissn: eissn: Reeived Septemer 2; Revised 2 Otoer 2; Aepted 9 Novemer 2 *Corresponding Author E-mil: jyjo@pknu..kr Copyright The Koren Soiety of Fisheries nd Aquti Siene 363

2 Fish Aqut Si 4(4), , 2 H H H seprtely in 7 L filter ylinders. The snd filter ws up-flow filtered to fluidize the snd, nd the other two were filtered y down-flow movement. The SSAs of the,, nd medi were 7,836, 3,287, nd 5 m 2 /m 3, respetively. P P PP P Ammoni loding rte : Wter flow (24 L/min) : Syntheti wstewter flow (7 ml/min) : Snd filter P : Pump : Polystyrene miroed filter PP : Peristlti pumps : Kldnes ed filter SW : Syntheti wstewter tnk H : Sumersile heter Fig.. Shemti digrm of reirulting quulture systems used for nitrifition effiieny studies of three different iofilter medi:,, nd. ws to ompre totl mmoni nitrogen (TAN) removl effiienies mong three iofilter medi, i.e., snd (), polystyrene miroeds (), nd Kldnes eds () under three different mmoni loding rtes in fresh wter. We lso onsidered the ost of eh medium. Mterils nd Methods System design The experiments were onduted in three losed reirulting system units. Eh system onsisted of one qurium (width, 45 m; length, 6 m; dimeter, 45 m), one iofilter ylinder (dimeter, 9 m; length, m), nd one pump (Fig. ). The totl wter volume used in eh system ws L. Wter from the qurium ws pumped into iofilter ylinder nd then flowed k to the qurium. A 4 L syntheti wstewter tnk ws instlled nd three peristlti pumps (Cheon Sei, Kore) were employed to distriute syntheti wstewter (7 ml/min) into eh of the iofilters. The omposition of the syntheti wstewter used in this study is shown in Tle. A sumersile heter ws used in eh system to mintin temperture t C. The three iofilter medi (,, nd ) were instlled Tle. Composition nd mount of hemils (g) used for mking 4 L of syntheti wstewter (modified from Roger nd Klementson, 985 ) Composition Tretment (g) * Tretment 2 (g) Tretment 3 (g) (NH 4 ) 2 SO NHCO N 2 HPO Gluose MnSO * Ammoni loding rte is 5 g m -3 d -, Ammoni loding rte is 25 g m -3 d -, Ammoni loding rte is 5 g m -3 d -. SW Three mmoni loding rtes of 5, 25, nd 5 g/m 3 wter per dy were pplied s tretments, 2, nd 3, respetively. These mmoni loding rtes were sed on the mmoni exretion rtes of Nile tilpi fingerlings (Oh, 2) nd equivlent to tilpi iomsses of 5, 25, nd 5 kg/m 3 wter. The syntheti wstewter ws moved with peristlti pumps, whih were djusted to 7 ml/min for eh filter system. This djustment provided L of syntheti wstewter dily to eh iofilter system. The flow rtes through the iofilters were djusted to 24 L/min. Preprtion of iofilter onditioning Ativted sludge ws tken from the iofilter of losed reirulting quulture system, the Intensive Bio-Prodution Kore system, t the Fish Culture Sttion Center, Pukyong Ntionl University, Kore, nd ultured in tnk with syntheti wstewter loding rte of 2 mg L - dy - for 2 weeks. When the nitrifying teri were inoulted into the experimentl iofilters, the mixed liquid suspended solid onentrtion of teri ws 4,5 mg/l. Bteri were ultured ontinuously in the syntheti wstewter with n mmoni loding rte of 5 g m -3 dy - for 3 weeks. When nitrifition hd stilized, wter from eh system ws hnged with ged groundwter of the sme temperture, nd the experiment ws strted. Conentrtions of TAN, nitrite-nitrogen ( -N), nd nitrte nitrogen ( -N) were monitored dily to ssess estlishment of nitrifiers nd their tivity. The limted ondition for eh iofilter ws determined when TAN nd -N onentrtions of the inlet nd outlet wter for eh iofilter system were mintined t onstnt onentrtions. Biofilter performne experiments were initited following this limtion. Before hnging the mmoni loding rte, wter from ll systems ws exhnged with new ged groundwter, nd the limtion proess ws repeted. Wter smpling Wter smples were olleted dily nd mesured in situ to monitor removl of nitrogenous ompounds. Smples were tken from three smpling points in eh iofilter system, i.e., from the qurium nd from the inlet nd outlet of the iofilter. These smples were nlyzed for TAN, -N, nd - N. Other prmeters, inluding wter temperture, dissolved oxygen (DO), nd ph were mesured dily in the qurium. Ammoni removl effiieny dt were olleted when TAN 364

3 Hrwnto et l. (2) Nitrifition Effiienies of Three Biofilter Medi onentrtions in ll iofilter systems deresed shrply during the limtion period. Equl volumes of syntheti wstewter ( L/dy) were dded to eh iofilter system ontinuously for 24 hours using the peristlti pumps. Consequently, L of wter from eh iofilter system ws removed dily to mintin totl wter volume in eh system. TAN (mg/l) Wter qulity mesurement methods TAN onentrtion ws mesured with n ORION mmoni meter (Model 72 A, USA). Ion hromtogrphy ws used to mesure nd onentrtions. Wter temperture nd DO were determined using OxyGurd. A Pin Point ph Monitor from Amerin Mrine In. ws used to determine ph. Volumetri mmoni removl rtes (VAR, g m -3 dy - ) nd rel mmoni removl rtes (AAR, g m -2 d - ) were lulted y the following eqution: -N (mg/l) VAR = (TAN in - TAN out ) Q V - (Oh, 2) AAR = (TAN in - TAN out ) Q V - S - (Kmstr et l., 998) 5 4 where TAN in nd TAN out re the onentrtions of TAN t the inlet nd outlet of the iofilter (g/m 3 ), respetively, Q is the totl wter flow through the filter (m 3 /dy), V is the volume of the filter ed (m 3 ), nd S is the SSA of the medium (m 2 /m 3 ) -N (mg/l) 3 2 Sttistil nlysis All sttistil nlyses were performed using the Minit sttistil softwre pkge relese version.2 (Minit, In., Stte College, PA, USA). The onentrtions of mmoni nd mmoni removl rtes in eh iofilter system were ompred using one-wy nlysis of vrine. The differenes etween mmoni onentrtion nd mmoni removl rte were nlyzed using Tukey s HSD test, with P <.5 onsidered signifint. Results Experimentl onditions Tempertures in,, nd remined in the rnge of C, nd the ph level remined in the rnge of during the study period. DO levels in the iofilters rnged from 6.7 to 9. mg/l. Biofilter onditioning The onditioning proess for eh tretment (mmoni loding rtes of 5, 25, nd 5 g m 3 d - ) ws strted in ll three iofilter systems t the sme time. The mmoni loding rte Dy Fig. 2. Chnges of totl mmoni nitrogen (TAN), nitrite nitrogen ( -N), nd nitrte nitrogen ( -N) in snd filter (), polystyrene miroed filter (), nd Kldnes ed filter () under mmoni loding rte of 5 g m -3 dy -. ws mintined t the sme mount for eh iofilter system throughout the entire period of onditioning nd the experiment. In tretment (mmoni loding rte of 5 g m 3 dy - ), TAN onentrtions in,, nd rehed their peks on dys 2, 3, nd 4, respetively, fter the experiment hd strted, nd the pek onentrtions were 3.5, 3.9, nd 4.7 mg/l, respetively (Fig. 2). Following the TAN pek, the mmoni onentrtions in,, nd deresed grdully nd rehed < mg/l on dys 8, 9, nd, respetively. When the TAN level entered the stedy stte ondition, the onentrtion of TAN remined < mg/l until the end of the experiment. The -N onentrtions in ll iofilter systems on dy were lmost mg/l. However, the onentrtions inresed shrply the next dy nd rehed their highest levels in,, nd on dys 3, 4, nd 5, respetively, with onentrtions of.44,.44, nd.5 mg/l. Then, -N onentrtions de

4 Fish Aqut Si 4(4), , 2 TAN (mg/l) -N (mg/l) -N (mg/l) Dy resed grdully nd were in stedy stte t pproximtely.2 mg/l. When TAN onentrtion entered the stedy stte, the -N onentrtions lso entered the stedy stte. -N onentrtions in,, nd inresed ontinuously from dy 2 of the experiment. After TAN entered stedy stte, the -N onentrtions in ll iofilters did not inrese s fst s efore. The highest onentrtions of -N in,, nd rehed 38.8, 36.5, nd 3.8 mg/l, respetively, t the end of the experimentl period. In tretment 2 (mmoni loding rte of 25 g m 3 dy - ), TAN onentrtions in,, nd peked on dy 5, nd the pek onentrtions were 9.2, 2., nd 22.3 mg/l, respetively (Fig. 3). Following the TAN pek, TAN onentrtions in,, nd deresed grdully nd rehed stedy stte t.7 mg/l on dy 4. Stedy stte TAN onentrtions remined until the end of the experiment. The -N onentrtion in tretment 2 flututed during Fig. 3. Chnges of totl mmoni nitrogen (TAN), nitrite nitrogen ( -N), nd nitrte nitrogen ( -N) in snd filter (), polystyrene miroed filter (), nd Kldnes ed filter () under mmoni loding rte of 25 g m -3 dy -. the first 8 dys. The onentrtions of -N in ll iofilter systems shrply inresed on dy 2 ut dropped on dys 3 nd 4 nd then rehed their highest level on dy 5 with onentrtions of 2.6, 3., nd 3.3 mg/l in,, nd, respetively. After peking, the -N onentrtions deresed shrply to.6 mg/l in ll iofilters; the onentrtions then inresed gin up to.2 mg/l in oth nd nd.7 mg/l in. Susequently, -N onentrtions deresed grdully nd were in stedy stte t pproximtely.4 mg/l in nd nd t pproximtely.8 mg/l in on dy 3. When the TAN onentrtion entered the stedy stte, the -N onentrtions hd lso entered stedy stte. -N onentrtions in,, nd inresed ontinuously up to dy 3 of the experiment. After TAN entered stedy stte, the -N onentrtions in ll iofilters did not inrese s rpidly s efore. The highest -N onentrtions in,, nd were 22.6, 27.4, nd 22.6 mg/l, respetively, t the end of the experiment. In tretment 3 (mmoni loding rte 5 g m 3 dy - ), TAN onentrtions in,, nd ll peked on dy 3 t 47.4, 49.2, nd 52.2 mg/l, respetively (Fig. 4). Following the TAN pek, the TAN onentrtions in,, nd deresed grdully nd rehed stedy stte in nd t.5 mg/l on dy 5 nd in t.9 mg/l on dy 3. Tretment 3 -N onentrtions flututed until dy. The pek -N onentrtion in ws rehed on dy 5 nd those in nd ourred on dy 4, with onentrtions of.6, 6.9, nd 7.9 mg/l, respetively. Susequently, -N onentrtions deresed grdully nd ttined stedy stte in nd t pproximtely.3 mg/l nd in t pproximtely.9 mg/l on dy 3. When the TAN onentrtion entered stedy stte, the -N onentrtions lso entered stedy stte. The -N onentrtions in,, nd inresed ontinuously from dy. After TAN entered stedy stte, the -N onentrtions in ll iofilters did not inrese s quikly s efore. The highest -N onentrtions in,, nd were 284.3, 28.9, nd mg/l, respetively, t the end of the experiment. Biofilter performne Signifint differenes were oserved in the volumetri mmoni removl rtes mong the three iofilters (Fig. 5). The highest volumetri mmoni removl rtes were found in for ll mmoni loding rtes of 5, 25, nd 5 g m 3 dy -, nd mmoni removl rtes were 39.3, 68.6, nd g m -3 dy -, respetively. Ammoni removl rtes in for the 5, 25, nd 5 g m 3 dy - loding rtes were 35., 57.4, nd 3.5 g m -3 dy -, respetively, wheres those in were 32., 42.5, nd 288. g m -3 dy -, respetively. The volumetri mmoni removl rtes inresed with inresing mmoni loding rtes in ll iofilter systems. showed the highest mmoni removl rte sed on 366

5 Hrwnto et l. (2) Nitrifition Effiienies of Three Biofilter Medi -N (mg/l) TAN (mg/l) iofilter re (Fig. 6). The rel mmoni removl rtes for under the mmoni loding rtes of 5, 25, nd 5 g m -3 dy - were 64., 285., nd mg m -2 dy -, respetively, followed y (.6, 47.9, nd 94.5 mg m -2 dy -, respetively) nd (5., 2.5, nd 4.2 mg m -2 dy -, respetively). Arel mmoni removl rtes lso inresed with inresing mmoni loding rtes in ll iofilters. Similr to the TAN removl effiienies, -N volumetri removl rtes under the mmoni loding rtes of 5, 25, nd 5 g m -3 dy - were the highest in with tul vlues of 6.2, 8.6, nd 8.6 g m -3 dy -, respetively, followed y those in (4.5, 7.3, nd 8. g m -3 dy -, respetively). -N volumetri removl rtes in under the mmoni loding rtes of 5, 25, nd 5 g m -3 dy - were 5.2, 5.6, nd 2.4 g m -3 dy -, respetively. The -N onentrtions in t the end of the experiment were the highest mong ll iofilter systems nd ll mmoni loding rtes. The -N onentrtions under mmoni loding rtes of 5, 25, nd 5 g m 3 d - were 39.5, 224.3, nd mg/l, respetively, followed y (37.3, 2., nd 28.9 mg/l, respetively) nd (32.3, 25.3, nd mg/l, respetively). -N (mg/l) Dy Fig. 4. Chnges of totl mmoni nitrogen (TAN), nitrite nitrogen ( -N), nd nitrte nitrogen ( -N) in snd filter (), polystyrene miroed filter (), nd Kldnes ed filter () under mmoni loding rte of 5 g m -3 dy -. Disussion Experimentl onditions Temperture rnged from C, DO rnged from mg/l, nd ph rnged from in ll systems under the different mmoni loding rtes. These vlues re in the pproprite rnges for nitrifition (Wheton et l., 994). TAN is the most ritil wter qulity prmeter in intensive reirulting systems. Aording to Wheton et l. (994) nd Losordo et l. (998), TAN should e mintined t < Volumetri Ammoni Removl Rte (g m -3 d - ) Snd Polystyrene miroed Kldnes ed Arel Ammoni Removl Rte (mg m -2 d - ) Snd Polystyrene miroed Kldnes ed Ammoni Loding Rte (g m -3 d - ) Ammoni Loding Rte (g m -3 d - ) Fig. 5. Comprisons of volumetri mmoni removl rtes of three different filter medi, snd, polystyrene miroed, nd Kldnes ed filter under three different mmoni loding rtes. Different letters on the rs in sme mmoni loding rte ws signifintly different (P <.5). Fig. 6. Comprisons of rel mmoni removl rtes of three different filter medi, snd, polystyrene miroed, nd Kldnes ed filter under three different mmoni loding rtes. Different letters on the rs in sme mmoni loding rte ws signifintly different (P <.5)

6 Fish Aqut Si 4(4), , 2 mg/l in intensive reirulting systems. TAN onsists of unionized mmoni (NH 3 ) nd ionized mmoni (NH 4+ ), nd the former is highly toxi to fish. The proportion of un-ionized TAN is dependent on ph nd wter temperture. When wter ph nd temperture inrese, un-ionized mmoni inreses. Biofilter limtion The TAN onentrtion in ll systems remined t > mg/l during the limtion period. However, fter the nitrifying teri hd fully developed (stedy-stte phse), TAN onentrtions in ll systems were mintined t < mg/l. - N, s produt of mmoni oxidtion, should e mintined t < mg/l (Wheton et l., 994; Losordo et l., 998). Men onentrtions of -N were mintined t < mg/l in ll tretments one TAN entered the stedy-stte phse. -N onentrtions were mg/l in ll quri with the three different mmoni loding rtes t the end of the study. These vlues re within eptle limits for quulture. Aquti speies n tolerte extremely high levels (>2 mg/l) of nitrte-nitrogen in prodution systems (Losordo et l., 998). Furthermore, Msser et l. (999) reported tht nitrte, the end produt of nitrifition, is reltively non-toxi exept t very high onentrtions (>3 mg/l). Biofilter performne hd the est TAN removl rte ompred to the other filter medi. This ws relted to the filter medi hrteristis. Snd medi hs very high SSA (7,836 m 2 /m 3 ) ompred to the SSAs of (3,287 m 2 /m 3 ) nd medi (5 m 2 /m 3 ). The polystyrene miroeds in showed etter performne thn tht of the Kldnes eds in. This result ws lso ssoited with the SSA. The SSA of ws higher thn tht of. Mlone nd Pfeiffer (26) noted tht snd nd polystyrene re high SSA medi. Wheton et l. (994) stted tht the higher SSA of medi, the more teri n grow per unit volume of medi, nd the totl mmoni removl per unit volume of filter will lso e higher. Furthermore, Lekng nd Kleppe (2) reported tht filter medi with higher SSAs provide lrger surfe res for teril growth. TAN onentrtions in ll systems should e mintined under the limit of < mg/l. The studied systems mintined TAN onentrtions t < mg/l, inditing good performne y ll three iofilters. TAN volumetri removl rtes in in the present study were g m -3 dy -, whih were lower thn those in the study of Shnel et l. (22). The volumetri removl rtes in their study were 624.-,56. g m -3 dy -, whih were due to the omintion of fluidized snd filter nd sreen filter nd reltively high mmoni loding rtes of,38-,339 g m -3 dy -. However, the present results re omprle with those of Summerfelt nd Shrrer (24), Pfeiffer nd Mlone (26), nd Summerfelt (26). Summerfelt nd Shrrer (24) found tht the volumetri mmoni removl rte ws. g m -3 dy - with n mmoni loding rte of 4.6 g m -3 dy -. Additionlly, the volumetri TAN removl rtes of Pfeiffer nd Mlone (26) were g m -3 dy - with mmoni loding rtes of g m -3 dy -. TAN removl rtes of Summerfelt (26) were g m -3 dy - when using Mpleton snd with mmoni loding rtes of g m -3 dy - nd were 7. g m -3 dy - when using Rihmond Dle snd with mmoni loding rtes of g m -3 dy -. The TAN volumetri removl rtes in of the present study were g m -3 dy - with mmoni loding rtes of 5-5 g m -3 dy -. These results re lower thn those of the two other studies. Greiner nd Timmons (998) reported tht TAN removl rtes y polystyrene were g m -3 dy - in high density tilpi ulture (68 kg/m 3 ). Timmons et l. (26) lso reported tht the TAN removl rte of polystyrene eds ws,2 g m -3 dy - with n mmoni loding rte of,56 g m -3 dy -. These differenes my e due to differenes in the operting hrteristis of the iofilter medi suh s flow rte, temperture, nd wter qulity prmeters. TAN volumetri removl rtes in of the present study ( g m -3 dy - ) were higher thn those in the studies of Lekng nd Kleppe (2), who used Norton rings nd Finturf nd Kldnes filters (22., 56.8, nd 6. g m -3 dy -, respetively). These differenes might e due to differenes in the SSA nd mmoni loding rte. The SSAs of Norton rings nd Finturf medi were 22 nd 284 m 2 /m 3, respetively, ompred to 5 m 2 /m 3 for in the present study. Lekng nd Kleppe (2) lso used lower mmoni loding rte (.5 g m -3 dy - ) thn tht used in the present study (5-5 g m -3 dy - ). The volumetri removl rte y in the present study ws lso higher thn tht in study y Ridh nd Cruz (2), who used polyethylene loks (8.9 g m -3 dy - ) nd polypropylene plsti hips (9.3 g m -3 dy - ), s oth medi lso hve lower SSA (2 m 2 /m 3 ) thn tht of Kldnes nd were treted with lower mmoni loding rte (.3 g m -3 dy - ). Compred with the results of Al-Hfedz et l. (23), who used plsti rolls, PVC pipes, nd sru pds (3.46, 2.95, nd 3.2 g m -3 dy -, respetively), the removl rte y in the present study showed higher performne, onsidering tht the previous study used lower mmoni loding rte (.8 g m -3 dy - ) thn tht in the present study. showed the lowest TAN removl rte sed on re (P <.5), wheres showed the highest TAN removl rte t ll mmoni loding rtes of 5, 25, nd 5 g m -3 dy -. The lowest vlue ws oserved in nd ws ttriuted to the high SSA of. -N onentrtions in ll iofilter systems were mintined under the limit (< mg/l), inditing tht the three iofilters performed well to mintin wter qulity. lwys showed higher -N volumetri removl rte thn tht of the other medi. showed the lowest removl rte nd ws in the middle. This result ws lso relted with the SSAs of the iofilter medi; the SSA of ws higher thn those of 368

7 Hrwnto et l. (2) Nitrifition Effiienies of Three Biofilter Medi nd. The highest -N onentrtions in,, nd were 284.3, 28.9, nd 25.3 mg/l, respetively, nd these were still under the >3 mg/l limit suggested y Msser et l. (999). Filter medi eonomis Biofilter medi preferene depends on mny ftors suh s surfe re, durility, nd ost. Low pitl ost is n importnt ftor to onsider when estlishing reirulting system for fish ulture (Al-Hfedh et l., 23). The pries of,, nd per ui meter sed on reent pries given y online sellers re pproximtely 5 US$, US$, nd 5 US$, respetively. Considering vritions in SSA mong these medi, the ost for otining m 2 surfe re is pproximtely 2 US$ for, 3 US$ for, nd 3 US$ for. However, requires high energy requirements to fluidize the snd ed (Wheton et l., 994; Summerfelt, 26), whih inreses energy osts. Therefore, polystyrene miroeds re reommended due to their good mmoni removl performne, light weight, nd high eonomy per surfe re volume. Aknowledgments Prtil funding of this study ws provided y the Kore Oen Reserh nd Development Institute through projet PE98593, PE98565 nd PK792. Referenes Al-Hfedh YS, Alm A nd Alm MA. 23. Performne of plsti iofilter medi with different onfigurtion in wter reirultion system for the ulture of Nile tilpi (Oreohromis nilotius). Aqu Eng 29, Eikerokk B. 99. Design nd performne of the BIOFISH wter reirultion system. Aqu Eng 9, Eikerokk B nd Ulgenes Y Reirultion tehnologies in Norwegin quulture. In: Proeedings of the 2nd Interntionl Conferene on Reirulting Aquulture. Liey GS nd Timmons MB, eds. Virgini Polytehni Institute nd Stte Universiy, Blksurg, VA, US, pp Greiner AD nd Timmons MB Evlution of the nitrifition rtes of miroed nd trikling filters in n intensive reirulting tilpi prodution fility. Aqu Eng 8, Kmstr A, vn der Heul JW nd Nijhof M Performne nd optimiztion of trikling filters on eel frms. Aqu Eng 7, Lekng OI nd Kleppe H. 2. Effiieny of nitrifition in trikling filters using different filter medi. Aqu Eng 2, Losordo TM, Msser MP nd Rkoy J Reirulting Aquulture Tnk Prodution Systems: An Overview of Critil Considertions. Southern Regionl Aquulture Center Pulition No. 45. Southern Regionl Aquulture Center, Soneville, MS, US. Mlone RF nd Beeher LE. 2. Use of floting ed filters to reondition reirulting wters in wrmwter quulture prodution systems. Aqu Eng 22, Mlone RF nd Pfeiffer TJ. 26. Rting fixed film nitrifying iofilters used in reirulting quulture systems. Aqu Eng 34, Msser MP, Rkoy J nd Losordo TM Reirulting Aquulture Tnk Prodution Systems: Mngement of Reirulting Systems. Southern Regionl Aquulture Center Pulition No Southern Regionl Aquulture Center, Soneville, MS, US. Oh SY. 2. Nitrogen loding rte of Nile Tilpi nd nitrifition rte of rotting iologil onttor. Unpulished Ph.D. disserttion. Pukyong Ntionl University, Busn, KR. Pfeiffer T nd Mlone RF. 26. Nitrifition performne of propeller-wshed ed lrifier supporting fluidized snd iofilter in reirulting wrmwter fish systems. Aqu Eng 34, Ridh MT nd Cruz EM. 2. Effet of iofilter medi on wter qulity nd iologil performne of the Nile tilpi Oreohromis nilotius L. rered in simple reirulting system. Aqu Eng 24, Rogers GL nd Klemetson SL Ammoni removl in seleted quulture wter reuse iofilters. Aqu Eng 4, Rusten B, Eikerokk B, Ulgenes Y nd Lygren E. 26. Design nd opertion of the Kldnes moving ed iofilm retors. Aqu Eng 34, Shnel N, Brk Y, Ezer T, Dfni Z nd vn Rijn J. 22. Design nd performne of zero-dishrge tilpi reirulting system. Aqu Eng 26, Summerfelt ST. 26. Design nd mngement of onventionl fluidized-snd iofilters. Aqu Eng 34, Summerfelt ST nd Shrrer MJ. 24. Design implition of ron dioxide prodution within iofilters ontined in reirulting slmonid ulture systems. Aqu Eng 32, Timmons MB, Holder JL nd Eeling JM. 26. Applition of miroed iologil filters. Aqu Eng 34, Wheton FW, Hohheimer JN, Kiser GE, Mlone RF, Krones MJ, Liey GS nd Ester CC Nitrifition filter priniples. In: Aquulture Wter Reuse Systems: Engineering Design nd Mngement. Development in Aquulture nd Fisheries Siene. Vol. 27. Timmons MB nd Losordo TM, eds. Elsevier, Amsterdm, NL, pp Wheton FW, Hohheimer JN, Kiser GE, Mlone RF, Krones MJ, Liey GS nd Ester CC Nitrifition filter design methods. In: Aquulture Wter Reuse Systems: Engineering Design nd Mngement. Development in Aquulture nd Fisheries Siene. Vol. 27. Timmons MB nd Losordo TM, eds. Elsevier, Amsterdm, NL, pp