﻿August, 
  1907 
  

  

  AMERICAN 
  HOMES 
  AND 
  GARDENS 
  

  

  313 
  

  

  the 
  foss 
  is 
  the 
  seat 
  of 
  very 
  active 
  anaerobic 
  fermentation, 
  in 
  

   consequence 
  of 
  which 
  a 
  portion 
  of 
  the 
  deposit 
  is 
  dissolved 
  

   and 
  another 
  portion 
  is 
  converted 
  into 
  gases, 
  chiefly 
  formene 
  

   and 
  hydrogen, 
  which 
  are 
  evolved 
  in 
  great 
  quantities. 
  Hence 
  

   the 
  sediment 
  does 
  not 
  accumulate 
  and 
  fill 
  the 
  foss. 
  Dr. 
  

   Calmette 
  found 
  only 
  about 
  200 
  cubic 
  feet 
  of 
  mud 
  in 
  a 
  septic 
  

   foss 
  of 
  nearly 
  9000 
  cubic 
  feet 
  capacity, 
  at 
  La 
  Madeleine, 
  

   after 
  a 
  year 
  of 
  service, 
  during 
  which 
  102 
  tons 
  of 
  solid 
  matter 
  

   in 
  suspension 
  had 
  entered 
  the 
  foss. 
  This 
  result 
  shows 
  the 
  

   great 
  effect 
  of 
  bacterial 
  action 
  in 
  decomposing 
  and 
  dissolving 
  

   sediment. 
  Part 
  of 
  the 
  dissolved 
  organic 
  matter 
  is 
  also 
  dis- 
  

   integrated 
  in 
  the 
  septic 
  fosses. 
  Altogether 
  half 
  the 
  organic 
  

   carbon 
  is 
  evolved 
  in 
  gaseous 
  form, 
  and 
  much 
  of 
  the 
  nitro- 
  

   genous 
  matter 
  is 
  converted 
  into 
  ammonia. 
  The 
  water 
  which 
  

   flows 
  from 
  the 
  fosses 
  is 
  still 
  filthy 
  and 
  foul-smelling, 
  but 
  it 
  

   holds 
  no 
  matter 
  in 
  suspension. 
  

  

  Bacterial 
  Contact 
  Bed 
  at 
  La 
  Madeleine-les-Lille 
  

  

  In 
  this 
  condition 
  it 
  goes 
  to 
  the 
  bacterial 
  beds 
  for 
  further 
  

   purification. 
  These 
  beds 
  are 
  rectangular 
  basins 
  about 
  4 
  

   feet 
  deep 
  and 
  from 
  10,000 
  to 
  20,000 
  square 
  feet 
  in 
  area. 
  

   The 
  bottom 
  is 
  covered 
  with 
  concrete, 
  slightly 
  inclined, 
  and 
  

   has 
  a 
  system 
  of 
  tile 
  drains. 
  The 
  basins 
  are 
  filled 
  with 
  coke 
  

   or 
  slag 
  broken 
  to 
  a 
  diameter 
  of 
  one 
  or 
  two 
  inches, 
  with 
  a 
  

   bottom 
  layer, 
  ten 
  inches 
  thick, 
  of 
  fragments 
  from 
  two 
  to 
  

   four 
  inches 
  in 
  diameter. 
  The 
  water, 
  distributed 
  by 
  sluices, 
  

   Hows 
  in 
  little 
  rivulets 
  over 
  the 
  entire 
  surface 
  of 
  the 
  bed. 
  

  

  These 
  bacterial 
  beds 
  may 
  be 
  operated 
  either 
  by 
  "double 
  

   contact" 
  (intermittent 
  system), 
  or 
  by 
  percolation 
  (contin- 
  

   uous 
  system). 
  In 
  the 
  intermittent 
  system 
  there 
  are 
  two 
  sets 
  

   of 
  beds, 
  to 
  which 
  the 
  water 
  goes 
  in 
  succession, 
  remaining 
  

   two 
  hours 
  in 
  contact 
  with 
  each 
  set. 
  After 
  the 
  beds 
  are 
  

   emptied 
  they 
  are 
  left 
  exposed 
  to 
  the 
  air 
  for 
  four 
  hours 
  be- 
  

   fore 
  being 
  used 
  again. 
  The 
  cycle 
  of 
  operations 
  of 
  each 
  bed 
  

   comprises 
  eight 
  hours, 
  thus: 
  one 
  hour 
  filling, 
  two 
  hours 
  

   filled, 
  one 
  hour 
  emptying 
  and 
  four 
  hours 
  airing. 
  Thus 
  each 
  

   bed 
  is 
  used 
  three 
  times 
  in 
  twenty-four 
  hours. 
  It 
  takes 
  a 
  

   volume 
  of 
  water 
  equal 
  to 
  one-third 
  of 
  its 
  cubic 
  capacity, 
  and 
  

   it 
  is 
  estimated 
  that, 
  for 
  average 
  conditions, 
  a 
  total 
  surface 
  of 
  

   five-eighths 
  of 
  a 
  square 
  foot, 
  including 
  the 
  beds 
  of 
  first 
  and 
  

   second 
  contact, 
  is 
  required 
  to 
  purify 
  one 
  cubic 
  foot 
  of 
  water 
  

   per 
  day. 
  Therefore 
  five 
  acres 
  would 
  suffice 
  for 
  a 
  city 
  of 
  

   100,000 
  inhabitants 
  with 
  a 
  daily 
  sewage 
  flow 
  of 
  350,000 
  

   cubic 
  feet. 
  

  

  The 
  changes 
  which 
  occur 
  during 
  these 
  operations 
  are 
  very 
  

   complex. 
  When 
  the 
  beds 
  are 
  flooded 
  the 
  slag 
  appears 
  to 
  

   extract 
  the 
  dissolved 
  organic 
  matter 
  as 
  fibers 
  extract 
  dyes 
  

   from 
  their 
  solutions. 
  Meanwhile 
  the 
  disintegration 
  of 
  the 
  

   organic 
  matter 
  by 
  the 
  bacteria 
  continues, 
  but 
  the 
  deposit 
  on 
  

   the 
  slag 
  is 
  attacked 
  and 
  decomposed 
  still 
  more 
  energetically 
  

   during 
  the 
  period 
  of 
  aeration. 
  The 
  products 
  of 
  decomposi- 
  

   tion 
  are 
  carbon 
  dioxide 
  water, 
  nitrogen 
  and 
  nitrates, 
  for 
  the 
  

  

  ammonia 
  which 
  is 
  formed 
  at 
  first 
  is 
  oxidized 
  and 
  converted 
  

   into 
  nitrates 
  by 
  certain 
  bacteria 
  called 
  nitrifying 
  ferments. 
  

   In 
  this 
  way 
  the 
  slag 
  is 
  freed 
  from 
  the 
  adhering 
  coat 
  of 
  or- 
  

   ganic 
  matter 
  and 
  made 
  ready 
  to 
  form 
  a 
  new 
  deposit 
  during 
  

   the 
  next 
  immersion. 
  On 
  leaving 
  the 
  first 
  bed 
  the 
  water 
  is 
  of 
  

   good 
  appearance 
  and 
  considerably 
  purified, 
  and 
  when 
  it 
  

   leaves 
  the 
  second 
  bed 
  it 
  has 
  parted 
  with 
  from 
  seventy-five 
  to 
  

   eighty-five 
  per 
  cent, 
  of 
  its 
  organic 
  matter. 
  In 
  this 
  condition 
  

   it 
  is 
  clear, 
  odorless 
  and 
  not 
  liable 
  to 
  become 
  putrid. 
  Fish 
  

   thrive 
  in 
  it 
  and 
  it 
  can 
  safely 
  be 
  thrown 
  into 
  streams. 
  

  

  This 
  intermittent 
  method 
  has 
  the 
  advantage 
  of 
  being 
  very 
  

   simple 
  and 
  requiring 
  no 
  machinery, 
  but 
  the 
  output 
  per 
  square 
  

   foot 
  of 
  surface 
  is 
  still 
  rather 
  small. 
  To 
  increase 
  it 
  attempts 
  

   have 
  been 
  made 
  to 
  make 
  the 
  flow 
  continuous 
  without 
  sup- 
  

   pressing 
  the 
  indispensable 
  aeration 
  of 
  the 
  beds. 
  This 
  result 
  

   is 
  obtained 
  by 
  employing 
  pressure 
  sprayers, 
  hydraulic 
  tourni- 
  

   quets, 
  inverting 
  droppers 
  or 
  intermittent 
  

   siphons. 
  

  

  The 
  bacterial 
  beds 
  are 
  made 
  six 
  or 
  

   seven 
  feet 
  thick, 
  and 
  complete 
  purifica- 
  

   tion 
  is 
  obtained 
  with 
  a 
  single 
  bed. 
  In 
  

   the 
  first 
  system 
  the 
  water 
  falls 
  con- 
  

   tinuously, 
  in 
  a 
  fine 
  rain, 
  upon 
  the 
  slag 
  

   from 
  spraying 
  nozzles 
  distributed 
  over 
  

   the 
  surface 
  of 
  the 
  bed, 
  through 
  which 
  it 
  

   percolates 
  slowly 
  and 
  emerges 
  in 
  a 
  puri- 
  

   fied 
  condition 
  at 
  the 
  bottom. 
  The 
  appa- 
  

   ratus 
  is 
  costly 
  and 
  is 
  frequently 
  clogged, 
  

   but 
  the 
  purification 
  is 
  perfect 
  and 
  the 
  out- 
  

   put 
  exceeds 
  three 
  cubic 
  feet 
  per 
  square 
  

   foot 
  per 
  day. 
  

  

  The 
  hydraulic 
  tourniquets 
  or 
  rotary 
  

   sprinklers 
  are 
  based 
  on 
  the 
  same 
  prin- 
  

   ciple. 
  The 
  whole 
  surface 
  of 
  the 
  bed 
  is 
  

  

  Flooding 
  a 
  Bacterial 
  Bed 
  of 
  First 
  Contact 
  at 
  La 
  Madeleine-les-Lille 
  

   Part 
  of 
  Second 
  Contact 
  Bed 
  Is 
  Shown 
  at 
  Right 
  

  

  sprinkled 
  by 
  a 
  single 
  central 
  apparatus 
  with 
  two 
  or 
  four 
  

   hollow 
  and 
  perforated 
  arms. 
  In 
  this 
  system 
  also 
  the 
  purifi- 
  

   cation 
  is 
  perfect, 
  and 
  the 
  output 
  is 
  nearly 
  four 
  cubic 
  feet 
  per 
  

   square 
  foot 
  per 
  day. 
  But 
  here, 
  too, 
  the 
  apparatus 
  is 
  ex- 
  

   pensive 
  and 
  liable 
  to 
  stoppages. 
  Besides, 
  it 
  is 
  often 
  disturbed 
  

   by 
  the 
  wind. 
  

  

  The 
  inverting 
  droppers 
  usually 
  consist 
  of 
  a 
  wheel 
  carrying 
  

   buckets 
  which 
  empty 
  themselves 
  on 
  the 
  bed. 
  The 
  wheel 
  

   automatically 
  moves 
  forward 
  at 
  each 
  emptying 
  and 
  so 
  the 
  

   entire 
  bed 
  is 
  watered. 
  One 
  of 
  the 
  best 
  devices 
  of 
  this 
  class 
  

   is 
  Fiddian's 
  rotary 
  distributor, 
  which 
  gives 
  results 
  as 
  good 
  

   as 
  those 
  obtained 
  with 
  sprinklers 
  and 
  works 
  with 
  much 
  

   greater 
  regularity. 
  

  

  Finally, 
  the 
  intermittent 
  siphons 
  devised 
  by 
  Dr. 
  Calmette 
  

   are 
  simply 
  siphons 
  which 
  fill 
  automatically 
  at 
  the 
  expiration 
  

  

  