J. Jpn. Soc. Soil Phys. No. 33, p.1-2-,**/, ******* Influence of Flow Rate on Nitrate Removal in Flow Process Toshio TABUCHI*, Hisao KURODA**, Akiko IKENOBE** and Mayumi HIRANO** * Former professor of The University of Tokyo ** College of Agriculture, Ibaraki University, Chuo -,++, Ami-machi, Inashiki-gun, Ibaraki, -***-3- Japan Abstract Influence of flow rate on nitrate removal in the flow process was examined in a paddy field plot. Flow rate was changed for three stages. In the first stage flow rate was controlled at *.*.* md +, in the second stage at *.*1- md + and in the third stage at *.+-0 md +. Corresponding to the increase of flow rate, water flows through a plot rapidly. The retention time is,0.- hours in the first stage, +0./ hours in the second stage and 3 hours in the third stage. With the increase of flow rate, the nitrate concentrations of outflow water gradually increased. The decrease of nitrate concentration through the flow process also changed. Coe$cients of nitrate removal rate (a) changed in a day, but the daily average values (a) in each stage were almost constant. Key words : Paddy field, Coe$cient of nitrate removal rate, Temperature, TOC + +321 +33- +330,**+,*** +332 a, b -,**/ q, +-,/ m, +.. m, -/ m, +,**- 2,. -* +/ ml s +,. - -2./.3 mm,0.- +0./ 3.* 0.,/ m / +* - EC, ph, DO, * -***--+.0-*+*. ** -***-3- -,++ : TOC
74 33,**/ NO --N, T-N, COD, TOC, TIC, T-P, / NO --N TOC TiO, - -+ -++ -3 +1,, 2,1,. mm + +*, + -+, + Fig. + Experimental plot. /,* -/ - -+-. t i t +, t, t +t + t + t, t,t - t -t,t, t -t. t.t /. t + t / t + i T i, t -,0,0 +0./,0,,,1 / 3 +/+2 +* Fig.,, Changes of water temperature.
: 75 Fig. - - Changes of mean water temperature. Fig... Explanation for water temperature in flow process. -, -,+ NO --N T-N NO --N /,1 0* 3 0 + NO --N 0.2 mg L +, ++.0 mg L +. +-.+ mg L + + 0 T-N NO --N NO --N T-N 3* T-N -,, COD, TOC, TIC COD / 0 COD +, mg L + TOC COD /- TIC COD, TOC CO, -,- T-P T-P *.+ mg L + T-P,1,2 -,. Cl EC Cl -/ mg L + -* mg L + EC Cl,/*-** mscm + --
76 33,**/ Fig. / / Changes of water qualities of outflow water. + mg L +, ms cm + Table + Daily mean values of concentrations of outflow water T-N NO --N COD TOC TIC Cl EC T-P 24+ 042 04+ -4. 34+ -/4*,/- *4*. +,4, ++40.4/ +43 14- -043,03 *4*. +.41 +-4+,4. +4. /4. -+4*,11 *4*- ++40 +*4/.4.,4, 14- -.4-,01 *4*. 3 +/, --+ NO --N NO --N 1
: 77 3 +/ Cl COD, TOC, ph, DO NO --N, EC. 0 Fig. 0 NO --N COD Relationship between flow rate and the concentration of NO --N and COD of outflow water., 2 mg L +. +. mg L + 3 +/ --, COD, TOC, TIC COD TOC +/ 3 TIC TOC --- T-P T-P +/ 3 --. ph ph +/ 2 --/ DO DO 3 +. mg L + --0 EC, Cl EC NO --N.+ NO --N.++ +321 NO --N +330 +332 a,,***,**+ Tabuchi,,**+ X LXoexpaq X L ; NO --N mg L + Xo ; NO --N mg L + a ; md + q ; md + x XxXoexpaxqL Xx ; x mg L + x ; m L; m X L Xo a q -,**+ Proc.,**+ R g m, d + q o, q L Rq oxoq LX L Rq oxoq L Xoexpaq qq oq L
78 33,**/ Fig. 1 1 Changes of water qualities in flow process.
: 79 RqXo+expaq Xo a R q.+, NO --N X L X L Xo X L q / X L a X L Xo X LXo, X LXo aq X LXoexpaq a q q - a aqlog ex LXo, q X LXo a *.*-- *.*-, *.*-, *.*-, q a.+- a a q a 2 *.*- md + *.*+ md + a o.+. a o a T a o a o 2 a a o a *.*+**.*+/ md + *.*+,*.*+- md +, a o a,0 a o a +,,+ a o,a 3 3 a o +/,+ +2 a * a o * a TOC TOC +,, 3 0 Table, Mean values of each stage q o Xo X L X LXo R a a o f md + mg L + mg L + gm, d + md + md + *4*.* +140 042 *4-3 *4.3 *4*-- *4*+-,4/ *4*1- +242 ++40 *40, *402 *4*-, *4*+,,41 *4+-0 +041 +-4+ *413 *40* *4*-, *4*+,,41
80 33,**/ Fig. 2 2 a, a o f Changes of coe$cient of nitrate removal rate (a), coe$cients of nitrate removal rate in laboratory (a o) and field coe$cient for nitrate removal (f). 3 Fig. 3 a a o TOC Changes of the values of a, a o and TOC concentration ( stage). +2 +.0+.3 mg L + - +.- mg L + TOC a,**+ - +2 - +332.+/ f a o a
: 81,- +33/ +330,**+ a a o faa o f 2 +,,+ f a o a a a o,./,.1., q.,+ q XxXoexpaxqL a*.*- q xl +* q q q*.*- m d + *.1 1* /*.,, q R RXoq+expaq a RXo q ++ RXo q a a *.*+ RXo q *.+ *.*+ q RXo*.*+ a*.*+ q*.+ R*.*+Xo R Xo *.*+ +32/,*** Tabuchi,,**+ a *.*+ q a ++ RXo a +* Fig. +* a*.*- md + The influence of flow rate (q) onno --N concentration in flow process (a*.*- md + ). ++ R Fig. ++ The influence of flow rate (q) on nitrate removal rate R.
82 33,**/ RaXo a *.*- q a *.*+ q +332 c,,***,*** Knight +33- q R*.01qXo,2q,,*** q / X L R a f a*.*-,,**+,*** : 02 3 : /30/.,**+ : +. : 3,+*+. +332 : 03, : +0,+03. +32/ : p +12. +321 : // 2 : /-/2. +33- : 0+ +, : +3,.. +33/ : 1, : -2. +330 : 0.. :,1-,. +332 a : 12 : +++2. +332 b : 12 : +3,.. +332 c : 2.22.,*** : +- : -/...,**+ : 21 :,1-0. Tabuchi, T. (,**+) : Nitrate removal in the flooded paddy field. Proceedings of the International Workshop on E$ciency of Purification Processes in Riparian Bu#er Zones, published by National Agricultural Research Center for Hokkaido Region. 2+3*.
: 83,**/ : 33 : 0/1,.,*** : 0 : ++,0. Knight, R.L., Ruble, R.W., Kadlec, R.H. and Reed, S. (+33-) : Wetland for Wastewater Treatment : Performance Database, Moshiri, G.A. edited Constructed Wetlands for Water Quality Improvement, Lewis Publishers, -//2. Proceedings of the International Workshop on E$ciency of Purification Processes in Riparian Bu#er Zones, edited by The Organizing Committee, published by National Agricultural Research Center for Hokkaido Region.,**+. - *.*.* md +, *.*1- md +. *.+-0 md +,0.- +0./ 3.* a *.*-, md + :,**. 2 +1 :,**/, +