Environmental Issues

Answer the following questions based on our trip to the wastewater treatment plant.

1.  Four levels of treatment may be in place at a waste water treatment plant.  For each level,
     describe the following  a) what is this level of treatment meant to do and b) how does the
     Lansing plant accomplishes this (briefly).

Pretreatment
Pretreatment  is  an  initial  process  which  removes  the  larger  waste  particles  like grits,  stones,  tree  limbs,  leaves  etc.  through  the  process  of  screening.
       
The  Lansing  plant  passes  the  influent  sewage  for  wet  well  grinding  and  passes  it   further  for  aerated  grit  removal  process.  The  separated  grits  are  sent  back  for  land  filling  and  flow  equalization  is  done  for  the  sewage  to  pass  through  the  primary  treatment  process.

Primary
In  this  process,  the  sewage  is  passed  through  large  sedimentation  tanks,  where  the sludge  can  settle  and  the  fats,  grease  etc  float  on  the  surface  of  the  tank.  The  purpose  of  this  process  is  to  convert  the  sewage  to  a  homogeneous  mixture,  so  that  it  can  easily    undergo  the  biological  and  chemical  processes.
         
In  the  plant,  this  process  is  basically  divided  into  two  parts.  One  is  North  Primary  Clarification  and  the  other  is  South  Primary  Clarification  and  the  process  is  more  or  less same.

Secondary
This  process  is  designed  for  the  biological  degradation  of  the  sewage  elements. This  is  classified  into  two  systems  one  is  fixed  film  method  which  includes  the  trickling filter  and  rotating  biological  contactors,  other  one  is  the  suspended  growth  system  which comprises  of  the  activated  sludge  process.  Activated  sludge  process  includes  a  number  of   processes  which  in  the  presence  of  dissolved  oxygen,  helps  the  growth  of  biological  floc,   which  ultimately  removes  the  organic  matter.
         
Lancing  plant  involves  the  aeration  of  sludge  in  the  north  and  south  plants    followed  by  secondary  clarification,  thereby  resulting  in  the  generation  of  the  activated   sludge.  This  process  is  repeated  again  and  again,  while  phosphorous  removal  being  a   parallel  activity.
                                 
Advanced (tertiary)
This  is  the  last  treatment  stage,  where  the  effluent  is  treated  to  improve  its   quality,  before  being  discharged  to  the  environment.

The  incoming  effluent  in  the  plant  is  disinfected  by  sodium  Hypochlorite  followed   by  a  tertiary  filtration  process.  The  resultant  effluent  is  de-chlorinated  and  aerated  before   it  is  discharged  to  the  Red  Cedar  River.

2.  What is sludge, and what can it be used for (this is different than activated sludge)
Sludge  is  the  residual,  homogeneous  matter  discharged  from  sewage  treatment processes,  or  treated  industrial  wastewater.

The  sludge  can  be  recycled  to  enrich  the  nutrient  content  of  croplands.  It  can  also  be  used  for  producing  biogas,  using  anaerobic  processes.


3.  Give 2 additional examples of a waste product being turned into a resource at the plant.
Residual  sludge  can  also  be  used  for  small  scale  production  of  electricity  in  the waste-to-energy  methodology.  The  landfill  material  decomposes  anaerobically  to  produce methane gas,  which  is  burned  on  site  to  produce  electricity.

Secondly,  the  residual  ash  obtained  from  the  incineration  process  is  reused  too.

4.  Where does the plant discharge its effluent  How does the Lansing plant disinfect the effluent before it is discharged
The  plant  discharges  its  effluent  to  the  Red  Cedar  River.

The  lancing  plant  adds  Sodium  Hypochlorite  to  the  secondary  clarifier  effluent  in the  tertiary  treatment  process  to  achieve  disinfection.

5.  How does the plant monitor the effluent it discharges
The  upgraded  Instrumentation  and  Controls  System  in  the  plant  enables  continuous monitoring  and  remotely  controls  the  plant  processes.  It  also  helps  in  monitoring  the  Plants  Final  Effluent  discharge  to  the  Red  Cedar  River  for  Dissolved  Oxygen,  pH,  and residual  Chlorine.

6.  Are there any materials that cant be removed from the water
Yes,  there  are  certain  materials  which  cant  be  completely  eliminated  from  the   water  like  certain  micro-organisms,  nitrogen,  phosphorous  and  a  few  heavy  metals.

7.  How do industries operating in Lansing cooperate with the plant to ensure proper disposal of wastes
Industries  help  to  provide  an  efficient  recycling  of  waste,  yard  waste  and  refuse collection.  They  also  assist  to  provide  a  clean  and  healthy  environment  to  enhance  the quality  of  life  for  the  inhabitants of  city  of  Lansing.