WR445:Waste Water
Treatment
Edwin Ndibalema
University of Dar es Salaam
Monday : 8:00 - 9.00 HRS, Wednesday : 11:00 -13:00 HRS
TEST: ?
Group of 10 members - By ?.
1
Sources of wastewater?
2
Sources of Wastewater
Domestic
Industrial
Infiltration/inflow
Domestic sewage flow
WASTEWATER CHARACTERISTICS
TOTAL
Volume (L/cap.
year)
Nitrogen
25,000-100,000
GREY
WATER***
25,000-100,000
2-4 kg/ca. year
5%
85%
10%
Phosphorus
0.3-0.8 kg/ca.
year
10%**
60%
30%
Potassium
1.4 -2.0 kg/ca.
year
30 kg/cap. year
34%
54%
12%
41%
12%
47%
104-106/100 ml
0*
107-109/100 ml
COD
Faecal Coliforms -
URINE
FAECES
500
50
* Health people ** can be as high as 50% *** values representative for industrialized
countries
Domestic sewage flow
Population served No
Urine
Toilet washing
Toilet Flushing
Hand Cleansing
Laundry water
Kitchen
Shower
Total Daily flow
Unit
No
l/c/d
l/c/d
l/c/d
l/c/d
l/c/d
l/c/d
l/c/d
l/d
Amount
Remark
1.5
1
6
0.5
15
15
15
54 l/c/d
Black water
Grey water
Black water
Grey water
Grey water
Grey water
Grey water
Source (Odhiambo 2009):Technical Guide to Ecosan Promotion
1. Experience in design : roughly 50 L/c/d of wastewater
2. Rely in Per capital water consumptions (70-80% will be Wastewater)
SANITATION SYSTEMS
LECTURE NOTES
DOMESTIC, INDUSTRIAL, INFLITRATION - PRINTING UNIT
Problems with untreated wastewater
-Oxygen Depletion
-Aesthetics –Odour, colour, foam, solids
-Eutrophication
-Diseases transmission-Cholera, Typhoid etc,
Wastewater Quality Parameters/components
The five most important parameters to characterize pollution of wastewater
are:
Other Literatures
• Solids
• Indicators of organic matter
• Nitrogen
• Phosphorus
• Indicators of faecal contamination
• Suspended Solids
•Inorganics
• Organic wastes (BOD)
• Nutrients
•Pathogens
Solids
In wastewater treatment, the solids can be classified according to
a) Their size and state
-Suspended solids(non-filterable)
-Dissolved Solids (Filterable)
-Colloidal Solids
b) Their chemical characteristics
-Volatile Solids (Organic)
-Fixed Solids (Inorganic)
c) Their settleability
-Settleable suspended solids
-Non-settleable suspended solids
Classification of Solids by size and state
Source (SPERLING,2007)
-Dissolved Solids with diameter < 10-3µm
-Colloidal Solids with diameter between 10-3 µm and 100 µm
-Suspended Solids (Particulate) with diameter > 100 µm
Classification of Solids by chemical characteristics
-The volatile solids represent an estimate of the organic matter in the solids
-The non-volatile solids (fixed) represents the inorganic or mineral matter
Volatile solids (VS)
– Also called “organic solids”
– That fraction of the total solids
which can be burnt (volatilised)
in the muffle oven at 520°C
– Only the volatile solids can be
broken down by anaerobic
digestion
– Inorganic (Fixed)(e.g. grit, sand)
Total solids (TS)
• = (organic solids + inorganic
solids)
• Measured after drying at 105°C
• “Dry solids” is another word for
total solids
Standard Methods:2540 SOLIDS
Total Solids Dried at 103 -105oC
𝑚𝑔
𝐴 − 𝐵 ∗ 1000
𝑇𝑆 ( ) =
𝐿
𝑆𝑎𝑚𝑝𝑙𝑒 𝑣𝑜𝑙𝑢𝑚𝑒 (𝐿)
– Where
A: Weight of dried residue +dish,g
B :Weight of dish,g
Volatile Solids after ignition at 550oC
𝑚𝑔
𝐴 − 𝐵 ∗ 1000
𝑉𝑆 ( ) =
𝐿
𝑆𝑎𝑚𝑝𝑙𝑒 𝑣𝑜𝑙𝑢𝑚𝑒 (𝐿)
– Where
A: Weight of dried residue +dish, before ignition,g
B : Weight of dried residue +dish, after ignition,g
Standard Methods:2540 SOLIDS
Suspended Solids Dried at 103 -105oC
𝑚𝑔
𝐴 − 𝐵 ∗ 1000
𝑆𝑆 ( ) =
𝐿
𝑆𝑎𝑚𝑝𝑙𝑒 𝑣𝑜𝑙𝑢𝑚𝑒 (𝐿)
– Where
A: Residue on filter after drying ,g
B :Total Mass of filter,g
Volatile Suspended Solids after ignition at 550oC
𝑚𝑔
𝐴 − 𝐵 ∗ 1000
𝑉𝑆S ( ) =
𝐿
𝑆𝑎𝑚𝑝𝑙𝑒 𝑣𝑜𝑙𝑢𝑚𝑒 (𝐿)
– Where
A: Residue on filter after drying ,g at 105 oC
B : Residue on filter after ignition at ,550 oC
Standard Methods:2540 SEMI SOLIDS SAMPLES
𝐴 − 𝐵 ∗ 100
𝑇𝑆 (%) =
𝐶−𝐵
𝑀𝑜𝑖𝑠𝑡𝑢𝑟𝑒 % = xxxxxxx? ?
𝐴 − 𝐷 ∗ 100 𝑉𝑆 (%) = 𝐷 − 𝐵 ∗ 100
𝑉𝑆 (TS%) =
𝐶−𝐵
𝐴−𝐵
𝐷 − 𝐵 ∗ 100
𝐹𝑆 (%) =
𝐴−𝐵
– Where
A: Weight of dried residue +dish,mg
B :Weight of dish,mg
C :Weight of wet sample+dish,mg
D :Weight of residue+dish after ignition
Standard Methods:2540 SEMI SOLIDS SAMPLES
– Example of the Reported Results in Literature:
Classification of Solids by Settleability
-Settleable solids are considered those that are able to settle in period of 1
hour.
-The volume of the solids accumulated in the bottom of a recipient called an
Imhoff cone is measured and expressed as mL/L.
– Generally,part of the solids can be separated from the liquid phase by gravity settling
– As rough guideline it can be expected that about 1/3 of the solids in raw-sewage are
particulate and can settle,1/3 are partculate but do not settle and 1/3 of the solids are
dissolved in the water
– -Approximate measure of the quantity that will be removed by primary sedimentation