﻿August, 
  1907 
  

  

  AMERICAN 
  HOMES 
  AND 
  GARDENS 
  

  

  311 
  

  

  The 
  Purification 
  of 
  Sewage 
  and 
  Factory 
  Waste 
  

  

  By 
  E. 
  Boullanger, 
  of 
  the 
  Pasteur 
  Institute 
  at 
  Lille 
  

  

  [HE 
  methods 
  which 
  have 
  been 
  devised 
  in 
  Finally, 
  the 
  dehydration 
  of 
  the 
  precipitate 
  by 
  filtering 
  and 
  

  

  recent 
  years 
  for 
  purifying 
  and 
  rendering 
  pressing 
  is 
  laborious 
  and 
  costly, 
  and 
  it 
  is 
  often 
  impossible 
  to 
  

  

  sewage 
  and 
  the 
  waste 
  water 
  of 
  factories 
  in- 
  dispose 
  of 
  the 
  product 
  as 
  its 
  value 
  as 
  an 
  agricultural 
  fertilizer 
  

  

  nocuous, 
  before 
  allowing 
  them 
  to 
  flow 
  into 
  is 
  uncertain. 
  Every 
  city 
  that 
  has 
  tried 
  chemical 
  methods 
  has 
  

  

  streams 
  to 
  poison 
  fish 
  and 
  possibly 
  human 
  encountered 
  these 
  difficulties, 
  so 
  that, 
  despite 
  their 
  seductive 
  

  

  beings, 
  may 
  be 
  classified 
  in 
  three 
  groups 
  : 
  simplicity, 
  attention 
  has 
  been 
  turned 
  to 
  methods 
  which 
  do 
  

  

  purely 
  chemical, 
  purely 
  biological 
  and 
  not 
  produce 
  bulky 
  and 
  worthless 
  waste 
  products, 
  

  

  mixed. 
  In 
  the 
  last 
  group, 
  part 
  of 
  the 
  organic 
  matter 
  is 
  pre- 
  The 
  first 
  employed 
  of 
  the 
  biological 
  processes 
  were 
  irriga- 
  

  

  cipitated 
  by 
  chemical 
  means, 
  and 
  the 
  water 
  is 
  then 
  further 
  tion 
  and 
  intermittent 
  filtration. 
  In 
  the 
  irrigation 
  method 
  the 
  

  

  purified 
  by 
  biological 
  methods. 
  water 
  to 
  be 
  purified 
  is 
  spread 
  over 
  cultivated 
  ground. 
  Here 
  

  

  The 
  principal 
  reagents 
  employed 
  in 
  chemical 
  purification 
  it 
  leaves 
  its 
  organic 
  matter, 
  which 
  becomes 
  converted, 
  through 
  

  

  are 
  ferric 
  sulphate, 
  ferric 
  chloride, 
  calcium 
  permanganate, 
  the 
  agency 
  of 
  bacteria, 
  into 
  nitrates, 
  water 
  and 
  gaseous 
  prod- 
  

  

  lime 
  and 
  chloride 
  of 
  lime. 
  When 
  any 
  of 
  these 
  substances 
  is 
  

   added, 
  in 
  suitable 
  proportion, 
  to 
  sewage 
  water, 
  a 
  precipitate 
  

  

  ucts. 
  This 
  method 
  has 
  been 
  adopted 
  for 
  the 
  purification 
  of 
  

   the 
  sewage 
  of 
  Paris. 
  It 
  requires 
  a 
  very 
  porous 
  soil 
  of 
  such 
  

  

  is 
  formed 
  which 
  entangles 
  and 
  carries 
  down 
  with 
  it 
  all 
  matter 
  chemical 
  composition 
  that 
  it 
  will 
  effectively 
  attract 
  and 
  ex- 
  

  

  in 
  suspension, 
  leaving 
  the 
  water 
  clear 
  and 
  partially 
  purified. 
  

   As 
  an 
  example 
  of 
  these 
  chemical 
  methods 
  we 
  may 
  take 
  the 
  

   process 
  of 
  purification 
  with 
  ferric 
  sulphate, 
  which 
  was 
  re- 
  

   cently 
  studied 
  at 
  the 
  experimental 
  station 
  at 
  La 
  Madeleine- 
  

   les-Lille. 
  The 
  sewage, 
  

   flowing 
  continuously 
  

   into 
  a 
  cistern, 
  receives, 
  

   through 
  an 
  adjustable 
  

   inlet 
  cock, 
  a 
  solution 
  of 
  

   ferric 
  sulphate 
  in 
  a 
  pro 
  

   portion 
  determined 
  by 
  a 
  

   preliminary 
  experiment, 
  

   and 
  is 
  then 
  pumped 
  

   into 
  an 
  elevated 
  clearing 
  

   basin, 
  which 
  overflows 
  

   into 
  a 
  second 
  basin. 
  

   The 
  solid 
  matter 
  ac- 
  

   cumulates 
  on 
  the 
  bot- 
  

   toms 
  of 
  the 
  basins, 
  

   chiefly 
  of 
  the 
  upper 
  one, 
  

   and 
  the 
  clear 
  water 
  

   flows 
  off 
  from 
  the 
  top 
  of 
  

   the 
  lower 
  basin. 
  When 
  

   the 
  basins 
  have 
  become 
  

   filled 
  with 
  soft 
  mud 
  

   they 
  are 
  emptied 
  by 
  

  

  Septic 
  Foss, 
  Showing 
  Sand 
  Chamber 
  

  

  tract 
  the 
  organic 
  matter 
  which 
  is 
  dissolved 
  in 
  the 
  water. 
  

   The 
  soil 
  must 
  also 
  be 
  well 
  aerated, 
  and 
  consequently 
  the 
  irri- 
  

   gation 
  must 
  be 
  intermittent 
  and 
  not 
  so 
  copious 
  as 
  to 
  drown 
  

   the. 
  land. 
  Finally, 
  the 
  purified 
  water 
  must 
  be 
  removed 
  from 
  

  

  the 
  subsoil 
  by 
  a 
  good 
  

   system 
  of 
  drainage. 
  

   When 
  all 
  these 
  condi- 
  

   tions 
  are 
  fulfilled 
  excel- 
  

   lent 
  results 
  are 
  obtained. 
  

   The 
  irrigated 
  land 
  is 
  

   usually 
  planted 
  with 
  

   vegetables 
  in 
  order 
  to 
  

   utilize 
  and 
  remove 
  the 
  

   nitrates, 
  which 
  are 
  

   the 
  ultimate 
  result 
  of 
  

   the 
  decomposition 
  of 
  the 
  

   nitrogenous 
  matter 
  by 
  

   bacteria. 
  

  

  The 
  irrigation 
  proc- 
  

   ess, 
  when 
  conducted 
  

   with 
  care, 
  furnishes 
  per- 
  

   fectly 
  pure 
  water, 
  but 
  it 
  

   is 
  attended 
  with 
  certain 
  

   serious 
  inconveniences. 
  

   It 
  is 
  not 
  always 
  possible 
  

   to 
  find, 
  near 
  a 
  city, 
  a 
  soil 
  

   of 
  the 
  requisite 
  depth 
  

  

  opening 
  sluices, 
  and 
  the 
  

  

  mud 
  is 
  passed 
  through 
  a 
  filter 
  press, 
  which 
  converts 
  it 
  into 
  and 
  permeability. 
  The 
  method 
  requires 
  vast 
  plots 
  of 
  land 
  

  

  cakes 
  containing 
  fifty 
  per 
  cent, 
  of 
  water. 
  Chemical 
  analysis 
  and 
  extensive 
  and 
  costly 
  piping. 
  The 
  best 
  soil 
  purifies 
  only 
  

  

  of 
  the 
  water 
  after 
  purification 
  shows 
  that 
  from 
  forty 
  to 
  sixty 
  

   per 
  cent, 
  of 
  the 
  soluble 
  organic 
  matter 
  has 
  been 
  precipitated. 
  

   The 
  water, 
  therefore, 
  is 
  only 
  about 
  half 
  purified. 
  

  

  The 
  advantages 
  of 
  the 
  chemical 
  method 
  are 
  the 
  following: 
  

   Unlike 
  the 
  biological 
  method, 
  it 
  is 
  applicable 
  to 
  water 
  rich 
  

   in 
  organic 
  matter 
  or 
  in 
  antiseptic 
  substances. 
  In 
  some 
  cases 
  

   it 
  permits 
  the 
  extraction 
  of 
  fats 
  and 
  nitrogenous 
  substances 
  

   of 
  commercial 
  value. 
  Finally, 
  it 
  does 
  not 
  require 
  an 
  ex- 
  

   tensive 
  plant. 
  

  

  On 
  the 
  other 
  hand, 
  the 
  chemical 
  method 
  offers 
  many 
  

   inconveniences. 
  It 
  is 
  very 
  difficult 
  to 
  regulate 
  the 
  quantity 
  

  

  about 
  one 
  quart 
  of 
  sewage 
  per 
  square 
  foot 
  per 
  day, 
  and 
  the 
  

   usual 
  rate 
  is 
  less 
  than 
  one-third 
  of 
  this. 
  Consequently 
  a 
  plot 
  

   of 
  about 
  800 
  acres 
  would 
  be 
  required 
  for 
  the 
  purification 
  of 
  

   the 
  sewage 
  of 
  a 
  city 
  of 
  100,000 
  inhabitants, 
  amounting 
  to 
  

   350,000 
  cubic 
  feet 
  per 
  day. 
  The 
  method 
  is 
  therefore 
  im- 
  

   practicable 
  in 
  many 
  cases, 
  owing 
  to 
  the 
  lack 
  or 
  great 
  cost 
  

   of 
  suitable 
  land. 
  

  

  If 
  the 
  sewage 
  is 
  allowed 
  to 
  flow 
  intermittently 
  upon 
  beds 
  

   of 
  coarse 
  sand, 
  a 
  much 
  greater 
  volume 
  of 
  water 
  can 
  be 
  puri- 
  

   fied. 
  This 
  fact 
  is 
  the 
  basis 
  of 
  the 
  method 
  of 
  purification 
  by 
  

   intermittent 
  filtration, 
  which 
  has 
  been 
  studied 
  chiefly 
  at 
  the 
  

  

  of 
  the 
  reagent 
  so 
  as 
  to 
  secure 
  satisfactory 
  purification 
  because 
  experimental 
  station 
  at 
  Lawrence, 
  Mass. 
  The 
  sewage 
  flows 
  

  

  the 
  proportion 
  should 
  vary 
  with 
  the 
  chemical 
  composition 
  of 
  

   the 
  sewage 
  or 
  waste, 
  and 
  this 
  may 
  vary 
  from 
  minute 
  to 
  

   minute. 
  At 
  best, 
  the 
  purification 
  is 
  incomplete, 
  and 
  the 
  

   water 
  still 
  contains 
  organic 
  matter 
  which 
  may 
  become 
  offen- 
  

   sive. 
  The 
  outlay 
  for 
  reagents, 
  even 
  the 
  cheapest 
  of 
  them, 
  

   is 
  heavy, 
  because 
  of 
  the 
  great 
  volume 
  of 
  water 
  to 
  be 
  treated. 
  

  

  at 
  regular 
  intervals 
  upon 
  beds 
  of 
  sand, 
  six 
  or 
  seven 
  feet 
  

   thick, 
  in 
  which 
  bacteria 
  rapidly 
  develop 
  and 
  destroy 
  all 
  or- 
  

   ganic 
  matter. 
  The 
  intermittent 
  irrigation 
  is 
  necessary 
  in 
  

   order 
  to 
  admit 
  air 
  to 
  the 
  beds 
  between 
  the 
  floodings. 
  This 
  

   method 
  can 
  be 
  employed 
  only 
  on 
  sandy 
  soils. 
  In 
  some 
  cases 
  

   crops 
  are 
  raised 
  on 
  the 
  filter 
  beds. 
  The 
  results 
  obtained 
  by 
  

  

  