subroutine sep_biozone !! ~ ~ ~ PURPOSE ~ ~ ~ !! This subroutine conducts biophysical processes occuring !! in the biozone layer of a septic HRU. !! ~ ~ ~ INCOMING VARIABLES ~ ~ ~ !! name |units |definition !! ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ !! bio_bd(:) |kg/m^3 |density of biomass !! bio_bod(:) |kg/ha |BOD concentration in biozone !! biom(:) |kg/ha |biomass of live bacteria in biozone !! bz_thk(:) |mm |thickness of biozone !! coeff_bod_dc(:) |m^3/day |BOD decay rate coefficient !! coeff_bod_conv(:)|none |BOD to live bacteria biomass conversion factor !! coeff_denitr(:) |none |Denitrification rate coefficient !! coeff_fc1(:) |none |field capacity calibration parameter 1 !! coeff_fc2(:) |none |field capacity calibration parameter 2 !! coeff_fecal(:) |m^3/day |Fecal coliform bacteria decay rate coefficient !! coeff_mrt(:) |none |mortality rate coefficient !! coeff_nitr(:) |none |Nitrification rate coefficient !! coeff_plq(:) |none |Conversion factor for plaque from TDS !! coeff_rsp(:) |none |respiration rate coefficient !! coeff_slg1(:) |none |slough-off calibration parameter !! coeff_slg2(:) |none |slough-off calibration parameter !! fcoli(:) |cfu/100ml |concentration of the fecal coliform in the biozone !! | |septic tank effluent !! ihru |none |HRU number !! i_sep(:) |none |soil layer where biozone exists !! isep_opt(:) |none |Septic system operation flag (1=active,2=failing,0=not operated) !! plqm |kg/ha |plaque in biozone !! rbiom(:) |kg/ha |daily change in biomass of live bacteria !! ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ !! ~ ~ ~ ~ ~ ~ END SPECIFICATIONS ~ ~ ~ ~ ~ ~ !! Coded by J.Jeong and C.Santhi. BRC, Temple TX !! Septic algorithm adapted from Siegrist et al., 2005 use septic_data_module use basin_module use pathogen_data_module use organic_mineral_mass_module use hru_module, only : hru, ihru, i_sep, iseptic, qstemm, bz_perc, isep, sep_tsincefail, & biom, plqm, bio_bod, fcoli, rbiom, isep use soil_module use time_module implicit none integer :: bz_lyr = 0 !none |soil layer where biozone exists integer :: isp = 0 !none |type of septic system for current hru integer :: j = 0 !none |hru integer :: nly = 0 ! | real*8 :: bz_vol = 0.d0 !m^3 |volume of biozone real*8 :: rtrate = 0.d0 ! | real*8 :: qin = 0.d0 !m^3 H2O |water in reach during time step real*8 :: qout = 0.d0 ! | real*8 :: rplqm = 0.d0 !kg/ha |daily change in plaque real*8 :: ntr_rt = 0.d0 !1/day |nitrification reaction rate real*8 :: dentr_rt = 0.d0 !1/day |denitrification reaction rate real*8 :: bod_rt = 0.d0 !1/day |BOD reaction rate real*8 :: fcoli_rt = 0.d0 !1/day |fecal coliform reaction rate real*8 :: rtof = 0.d0 !none |weighting factor used to partition the ! |organic N & P concentration of septic effluent ! |between the fresh organic and the stable ! |organic pools real*8 :: xx = 0.d0 !none |temp variable, used to hold calculated ! |value needed in later equations real*8 :: bodi = 0.d0 ! | real*8 :: bode = 0.d0 ! | real*8 :: rnit = 0.d0 !kg/ha |nitrification during the day real*8 :: rdenit = 0.d0 !kg/ha |denitrification during the day real*8 :: rmort = 0.d0 !kg/ha |daily mortality of bacteria real*8 :: rrsp = 0.d0 !kg/ha |daily resparation of bacteria real*8 :: rslg = 0.d0 !kg/ha |daily slough-off bacteria real*8 :: rbod = 0.d0 !mg/l |daily change in bod concentration real*8 :: rfcoli = 0.d0 !cfu/100ml |daily change in fecal coliform real*8 :: nh3_begin = 0.d0 ! | real*8 :: nh3_end = 0.d0 ! | real*8 :: nh3_inflw_ste = 0.d0! | real*8 :: no3_begin = 0.d0 ! | real*8 :: no3_end = 0.d0 ! | real*8 :: no3_inflow_ste = 0.d0! | real*8 :: bza = 0.d0 ! | real*8 :: qi = 0.d0 ! | real*8 :: nperc = 0.d0 ! | real*8 :: nh3_init = 0.d0 ! | real*8 :: no3_init = 0.d0 ! | real*8 :: hvol = 0.d0 ! | real*8 :: solpconc = 0.d0 ! | real*8 :: solpsorb = 0.d0 ! | real*8 :: qlyr = 0.d0 ! | real*8 :: qsrf = 0.d0 ! | real*8 :: solp_init = 0.d0 ! | real*8 :: solp_begin = 0.d0 ! | real*8 :: solp_end = 0.d0 ! | real*8 :: svolp = 0.d0 ! | real*8 :: totalp = 0.d0 ! | real*8 :: ctmp = 0.d0 ! | real*8 :: percp = 0.d0 ! | j = ihru nly = soil(j)%nly isep = iseptic(j) isp = sep(isep)%typ !! J.Jeong 3/09/09 bz_lyr = i_sep(j) bza = hru(j)%area_ha bz_vol = sep(isep)%thk * bza * 10. !m^3 qlyr = qstemm(j) qsrf = 0 !temperature correction factor for bacteria growth/dieoff (Eppley, 1972) !ibac = 1 !there should be a loop for all pathogens in this hru !ctmp = path_db(ibac)%t_adj ** (soil(j)%phys(bz_lyr)%tmp- 20.) ctmp = 1. ! initial water volume qi = (soil(j)%phys(bz_lyr)%st + soil(j)%ly(bz_lyr-1)%prk + qstemm(j)) * & bza * 10. !m3 ! STE volume qin = qstemm(j) * bza * 10. ! m^3 ! leaching to septic layer qout = bz_perc(j) * bza * 10. !m3/d ! final volume hvol = soil(j)%phys(bz_lyr)%st * bza * 10. rtof = 0.5 nh3_init = soil1(j)%mn(bz_lyr)%nh4 no3_init = soil1(j)%mn(bz_lyr)%no3 solp_init = soil1(j)%mp(bz_lyr)%lab !! Failing system: STE saturates upper soil layers if (sep(isep)%opt == 2) then ! increment the number of failing days if(sep_tsincefail(j)>0) sep_tsincefail(j) = sep_tsincefail(j) + 1 ! convert the failing system into an active system if duration of failing ends if (sep_tsincefail(j) >= sep(isep)%tfail) then sep(isep)%opt = 1 soil(j)%phys(bz_lyr)%ul=sep(isep)%thk * & (soil(j)%phys(bz_lyr)%por - soil(j)%phys(bz_lyr)%wp) soil(j)%phys(bz_lyr)%fc=sep(isep)%thk*(soil(j)%phys(bz_lyr)%up- & soil(j)%phys(bz_lyr)%wp) soil1(j)%mn(bz_lyr)%nh4 = 0 soil1(j)%mn(bz_lyr)%no3 = 0 soil1(j)%hsta(bz_lyr)%n = 0 soil1(j)%hsta(bz_lyr)%p = 0 soil1(j)%tot(bz_lyr)%p = 0 soil1(j)%mp(bz_lyr)%lab = 0 soil1(j)%mp(bz_lyr)%act = 0 biom(j) = 0 plqm(j) = 0 bio_bod(j) = 0 fcoli(j) = 0 sep_tsincefail(j) = 0 end if return endif !! Active system !! Water content(eqn 4-12), biozone hydraulic conductivity(eqn 4-9), !! and percolation (eqn 4-8,10,11) are computed in percmain/percmicro ! Add STE nutrients to appropriate soil pools in mass unit xx = qin / bza / 1000. ! used for unit conversion: mg/l -> kg/ha soil1(j)%mn(bz_lyr)%no3 = soil1(j)%mn(bz_lyr)%no3 + xx * & (sepdb(sep(isep)%typ)%no3concs + & sepdb(sep(isep)%typ)%no2concs) soil1(j)%mn(bz_lyr)%nh4 = soil1(j)%mn(bz_lyr)%nh4 + xx * & sepdb(sep(isep)%typ)%nh4concs soil1(j)%hsta(bz_lyr)%n = soil1(j)%hsta(bz_lyr)%n + xx * & sepdb(sep(isep)%typ)%orgnconcs*rtof soil1(j)%tot(bz_lyr)%n = soil1(j)%tot(bz_lyr)%n + & xx*sepdb(sep(isep)%typ)%orgnconcs*(1-rtof) soil1(j)%hsta(bz_lyr)%p = soil1(j)%hsta(bz_lyr)%p + xx * & sepdb(sep(isep)%typ)%orgps*rtof soil1(j)%tot(bz_lyr)%p = soil1(j)%tot(bz_lyr)%p + xx * & sepdb(sep(isep)%typ)%orgps* & (1-rtof) soil1(j)%mp(bz_lyr)%lab = soil1(j)%mp(bz_lyr)%lab + xx* & sepdb(sep(isep)%typ)%minps bio_bod(j)=bio_bod(j)+xx*sepdb(sep(isep)%typ)%bodconcs ! J.Jeong 4/03/09 bodi = bio_bod(j) * bza / qi * 1000. !mg/l !! Field capacity in the biozone Eq. 4-6 ! soil(j)%phys(bz_lyr)%fc = soil(j)%phys(bz_lyr)%fc + sep(isep)%fc1 & * (soil(j)%phys(bz_lyr)%ul - soil(j)%phys(bz_lyr)%fc) ** & sep(isep)%fc2 * rbiom(j) / (sep(isep)%bd * 10) !! Saturated water content in the biozone - Eq. 4-7 ! mm = mm - kg/ha / (kg/m^3 * 10) soil(j)%phys(bz_lyr)%ul = soil(j)%phys(bz_lyr)%por * & sep(isep)%thk-plqm(j) /(sep(isep)%bd*10.) if(soil(j)%phys(bz_lyr)%ul.le.soil(j)%phys(bz_lyr)%fc) then soil(j)%phys(bz_lyr)%ul = soil(j)%phys(bz_lyr)%fc sep(isep)%opt = 2 endif !! Respiration rate(kg/ha) Eq. 4-2 rrsp = ctmp * sep(isep)%rsp * biom(j) !! Mortality rate(kg/ha) Eq. 4-3 rmort = ctmp * sep(isep)%mrt * biom(j) !! Slough-off rate(kg/ha) rslg = sep(isep)%slg1 * bz_perc(j) ** sep(isep)%slg2 * biom(j) !! Build up of plqm(kg/ha) Eq.4-5 ! kg/ha (perday) = kg/ha + dimensionless * m^3/d * mg/l / (1000*ha) rplqm = (rmort - rslg) + sep(isep)%plq * qin * & sepdb(sep(isep)%typ)%tssconcs / (1000. * bza) rplqm = max(0.,rplqm) !! Add build up to plqm ! kg/ha = kg/ha + kg/ha plqm(j) = plqm(j) + rplqm nh3_inflw_ste = xx * sepdb(sep(isep)%typ)%nh4concs no3_inflow_ste = xx*(sepdb(sep(isep)%typ)%no3concs + & sepdb(sep(isep)%typ)%no2concs) nh3_begin = soil1(j)%mn(bz_lyr)%nh4 no3_begin = soil1(j)%mn(bz_lyr)%no3 solp_begin = soil1(j)%mp(bz_lyr)%lab !! Add STE f.coli concentration by volumetric averaging xx = 10.* soil(j)%phys(bz_lyr)%st * bza / (qin & + 10.* soil(j)%phys(bz_lyr)%st * bza) fcoli(j) = fcoli(j) * xx + sepdb(sep(isep)%typ)%fcolis * (1.- xx) ! J.Jeong 3/09/09 !! nutrients reaction rate (Equation 4-13) rtrate = biom(j) * bza / (bz_vol * soil(j)%phys(bz_lyr)%por) !! BOD (kg/ha) 4-14 ! bod_rt = max(0.,sep(isep)%bod_dc * rtrate) !bod if (bod_rt>4) bod_rt=4 rbod = bodi * (1.- Exp(-bod_rt)) bode = bodi - rbod !mg/l bio_bod(j) = bode * (soil(j)%phys(bz_lyr)%st * 10)/1000. !kg/ha !! Fecal coliform(cfu/100ml) Eq 4-14, J.Jeong 3/09/09 fcoli_rt = max(0.,sep(isep)%fecal * rtrate) !fecal coliform rfcoli = fcoli(j) * (1.- exp(-fcoli_rt)) fcoli(j) = fcoli(j) - rfcoli !! change in nh3 & no3 in soil pools due to nitrification(kg/ha) Eq.4-13, 4-14 ntr_rt = max(0.,sep(isep)%nitr * rtrate) !nitrification rnit = soil1(j)%mn(bz_lyr)%nh4 * (1. - Exp(-ntr_rt)) !! J.Jeong 4/03/09 soil1(j)%mn(bz_lyr)%nh4 = soil1(j)%mn(bz_lyr)%nh4 - rnit !J.Jeong 3/09/09 soil1(j)%mn(bz_lyr)%no3 = soil1(j)%mn(bz_lyr)%no3 + rnit !J.Jeong 3/09/09 !ammonium percolation nperc = 0.2 * qout / qi * soil1(j)%mn(bz_lyr)%nh4 nperc = min(nperc,0.5 * soil1(j)%mn(bz_lyr)%nh4) soil1(j)%mn(bz_lyr)%nh4 = soil1(j)%mn(bz_lyr)%nh4 - nperc soil1(j)%mn(bz_lyr+1)%nh4 = soil1(j)%mn(bz_lyr+1)%nh4 + nperc !! denitrification,(kg/ha) Eq 4-14 dentr_rt = max(0.,sep(isep)%denitr * rtrate) !denitrification rdenit = soil1(j)%mn(bz_lyr)%no3 * (1. - Exp(-dentr_rt)) !J.Jeong 3/09/09 soil1(j)%mn(bz_lyr)%no3 = soil1(j)%mn(bz_lyr)%no3 - rdenit !J.Jeong 3/09/09 !soil volume for sorption: soil thickness below biozone svolp = (soil(j)%phys(nly)%d - sep(isep)%z) * bza * 10. !m3, !max adsorption amnt: linear isotherm, McCray 2005 solpconc = soil1(j)%mp(bz_lyr)%lab * bza / qi * 1000. !mg/l solpsorb = min(sep(isep)%pdistrb * solpconc,sep(isep)%psorpmax) !mgP/kgSoil solpsorb = 1.6 * 1.e-3 * solpsorb * svolp * & (1-soil(j)%phys(bz_lyr)%por) !kgP sorption potential !check if max. P sorption is reached if(soil1(j)%mp(bz_lyr)%lab * bza<solpsorb) then totalp = soil1(j)%mp(bz_lyr)%lab + soil1(j)%mp(bz_lyr)%act solp_end = sep(isep)%solpslp * totalp + sep(isep)%solpintc if (solp_end > soil1(j)%mp(bz_lyr)%lab) then solp_end = soil1(j)%mp(bz_lyr)%lab endif soil1(j)%mp(bz_lyr)%act = soil1(j)%mp(bz_lyr)%act + & soil1(j)%mp(bz_lyr)%lab - solp_end soil1(j)%mp(bz_lyr)%lab = solp_end endif solpconc = soil1(j)%mp(bz_lyr)%lab * bza / qi * 1000. !mg/l percp = 0.01*solpconc * qout / bza * 1.e-3 soil1(j)%mp(bz_lyr)%lab = soil1(j)%mp(bz_lyr)%lab - percp !kg/ha soil1(j)%mp(bz_lyr+1)%lab = soil1(j)%mp(bz_lyr+1)%lab + percp !kg/ha nh3_end = soil1(j)%mn(bz_lyr)%nh4 no3_end = soil1(j)%mn(bz_lyr)%no3 solp_end = soil1(j)%mp(bz_lyr)%lab !! daily change in live bacteria biomass(kg/ha) Eq. 4-1 ! kg/ha = m^3 * mg/L/(1000.*ha)6 rbiom(j) = ctmp*sep(isep)%bod_conv*(qin* & sepdb(sep(isep)%typ)%bodconcs - & qout * bode) / (1000. * bza) - (rrsp + rmort + rslg) rbiom(j) = max(1.e-06,rbiom(j)) !! total live biomass in biozone(kg/ha) biom(j) = biom(j) + rbiom(j) 1000 format(3i5,50es15.4) return end subroutine sep_biozone