Sewage sludge production, management, Sewage treatment, activated sludge,

1. Use of Sewage andUse of Sewage and
sludge as waste materialsludge as waste material
Prof. P. K. Mani
BCKV, India

2. Sewage has two components,
Solid portion technically known as sludge
Liquid portion, commonly known as
sewage water or effluent . The raw or crude
sewage consists mainly of water carrying various solids
partly in soln and partly in suspension
Both the components of sewage are used in increasingBoth the components of sewage are used in increasing
crop production but due tocrop production but due to bacterial contaminationbacterial contamination
untreated sewage is not advocated for growinguntreated sewage is not advocated for growing
vegetablesvegetables
Bacterial contamination is reduced by fermentation and
Oxidation treatment

3. India generate 38354 million litres per day (MLD) sewage
in major cities of India per year but the sewage treatment
capacity is only of 11786 MLD. (Kaur et al., 2012).
Production of sludge is estimated to be around 1200
tonnes per day, potentiality is 4000 tonnes per day
Nutrient potential of available sewage in India is
estimated to be more than 350,000 tonnes N,
150,000 tonnes P and 200,000 tonnes K per year
(Juwarkar et al., 1991).
Sewage sludge –a potential threat to heavy metal
pollution in Indian soils

4. Domestic Waste water management practice in INDIA
•In urban area sewage/sullage generation is 80% of
water supply
•40000 MLD of sewage/ sullage is generated in
cities/towns in India
• Approximately 30% sewage/ sullage (12000 MLD) is
treated in STP
•Mostly untreated sewage/ sullage is discharged in
water bodies
•Treated sewage/ sullage use in agriculture/ farming is
limited
Sullage : waste water from household sinks, showers, and baths, but not
waste liquid or excreta from toilets.

5. Disposal of sewage effluents for irrigation
 Irrigation with sewage or sewage mixed with industrial effluents results
in saving of 25 to 50 % of N and P fertilizer and leads to 15-27 % higher
crop productivity, over the normal waters (Anonymous, 2004).
In India about 73,000 ha of (Strauss and Blumenthal, 1990) peri- urban
agriculture is subject to wastewater irrigation.
In peri-urban areas, farmers usually adopt year round, intensive
vegetable pdn systems or other perishable commodity like fodder and
earn up to 4 times more from a unit land area compared to freshwater
(Minhas & Samra, 2004).

7. Settled sludge :- Produced by plain sedimentation
Digested sludge:- Digested sludge is obtained from raw
sewage through settling by gravity and sedimentation.
The solid parts subsequently digested anaerobically for a
period of 10-15 days. This digested material is then pumped
in suitable beds for drying out. This sludge’s usually gave an
offensive odour but they are free from pathogenic
organisms present in unprocessed sludges
Activated sludge: produced by a special rapid aerobic
treatment (and using a biological floc composed of
bacteria and protozoa) of sewage that results in
coagulation and settling of suspended materials. This pdt
is superior to digested sludge and has no offensive adour.
Chemically precipitated sludge:- Produced by treatment
of certain chemicals to remove certain poisonous
compounds and heavy metals as also to precipitate the
dispersed material.

8. Basic flow of sewage sludge composting process

9. ACTIVATED SLUDGE PROCESS (Conventional)ACTIVATED SLUDGE PROCESS (Conventional)
Raw
Sewage
Grit
Chamber
Primary
Sedimen
tation
Tank
Aeration
Tank
Secondary
Sedimentat
ion Tank Treated
Effluent
Sludge
Disgestor
RETURN SLUDGE
Sludge
Lagoon
Excess
Sludge
Bio-Gas
Drying BedDrying Bed MANURE
Grid
Chamber/
Screens
Grit includes sand, gravel, cinder, or other heavy solid materials that are “heavier”
(higher sp. gravity) than the organic biodegradable solids in the wastewater. Grit also
includes eggshells, bone chips, seeds, coffee grounds, and large organic particles,
such as food waste. A cinder is a pyroclastic material, are extrusive igneous rocks

10. Waste Stabilization PondWaste Stabilization Pond
ScreenScreen T.ET.E
G C
(optional)
An P FP MP MP MP MP
G.C. : Grit Chamber; An. P : Anaerobic Pond
F. P. : Facultative Pond; M.P. : Maturation Pond
Grid
Chamber
Sand Trap
A screen is a device with openings, generally of uniform size, that is used to
retain solids found in the influent wastewater to the treatment pant. The
principal role of screening is to remove coarse materials (pieces of wood,
plastics, rags, papers, leaves, roots etc.) from the flow stream

13. Activated sludge contains :
3-6% N, ~ 2% P2O5 and 1% K2O
in form a that can become readily available when applied
to soil. (ISSS,2009)
On an average, the sewage sludge has the following
composition on oven dry basis
Composition Amount on oven dry weight basis (%)
Organics 40-50
Inert materials 30-40
Bio-resistant organics 10-15
Miscellaneous substances 5-8

14. Composition of Sludge
N (1.5 – 3.5% ) P (0.75- 4.0%) K (0.3- 0.6%)
Sewage: Effluent waters which should be removed from
settlements and industrial enterprises are
known as Sewage
food wastes, various washings and laundry wastes,
waters from lavatories, baths etc.
waste waters are unstable polydispersed system
Inorganic impurities are sand, clay, particles of ore,
slag, chalk, mineral salts, mineral oils
Municipal sewage

15. General Standard of Treated Waste Water for
Disposal in Land for Irrigation
• Suspended solids: 200 mg/l
• pH : 5.5-9.0
• Oil & Grease : 10 mg/l
• BOD : 100 mg/l
• Arsenic : 0.2 mg/l ?0.2 mg/l ?
• Cyanide : 0.2 mg/l
• Bio-assay Test: 90% survival of fish after
96 hrs in 100% effluent

16. Sewage water : can be used as an irrigation source.
However, it should be treated before application to
fields.
Soil sickness: results from excessive organic and N
loading, which causes anaerobiosis and imbalance in
C:N and C:P.
Excessive N-loading: also induces production of more
foliage, resulting in less fruiting, particularly in the
case of vegetables like brinjal, okra, chillies.
The yield decline: due to continuous application of
untreated sewage water is primarily due to blocking of
soil pore spaces by colloidal matter. The soil quickly
becomes sewage-sick.

18. Industrial sewage
special methods of the treatment are reqd.
(i) NaCN+ H2SO4→ (Na)2SO4 + HCN (260
C)
(ii) NaCN + HOCl = CNCl + NaOH
CNCl + H2
O → HCNO + HCl
HCNO + Cl2
+ H2O → CO2 + N2 + 2HCl
(at pH 10.0)
Cyanogen
chloride
Cyanic acid

20. Heavy metal composition of sewage sludge from different
cities in India
City Cu Zn Cd Cr Ni Pb
mg/kg
Ahmeda
bad
535 2147 3.5 60.4 32.3 76.8
Delhi 440 1610 5.5 53.5 81.5 34.5
Nagpur 272 832 1.5 49.2 14.8 24.3
Chennai 210 935 8.3 38.5 60.5 16.6
Jaipur 265 1720 7.3 17.6 37.5 66.9
Source : Maity et al (1992).

21. DTPA-extractable heavy metals in soils under different crops
irrigated with sewage and underground water
Crop Source of Zn Fe Cu Mn Cd
irrigation water mg/kg
Berseem Sewage 13.4 75.3 24.4 33.2 0.119
Underground 4.20 38.0 7.80 28.4 0.074
Spinach Sewage 41.2 65.6 32.2 28.8 0.253
Underground 4.20 59.4 7.00 24.4 0.079
Coriander Sewage 21.1 69.0 49.4 23.0 0.208
Underground 6.60 32.4 9.50 18.4 0.054
Source: Sharma and Kansal(1986)

22. DTPA-extractable heavy metal status in Peri-Urban Soils
(treated with sewage) during Summer of 2001
Soil sample DTPA-extractable heavy metal content/mg.kg-1
Pb Cd Cr
Kalyani 0.35 1.70 0.63
Mahishtala-2, Dhapa 0.70 1.00 7.207.20
Mathpukur 1.08 1.21 4.18
Tangra, Dhapa 1.52 12.6 4.96
Bantala 1.68 17.0 18.9
South Mahishtala, Tiljala 1.70 0.58 8.30
Barasat 2.88 1.04 3.54
Titagarh 1.96 1.01 2.30
Source: Sanyal (2002)

23. Distillery Effluents (Spent wash)
Distillery is one of the most important agri based industries in India for
manufacturing of ethyl alcohol from molasses. A large volume of foul
smelling effluent which is commonly known as distillery effluent or spent
wash is generated.
 Usually with 1 L of alcohol production 12-15L spent wash effluent
is generated. Approximately 40 billion Litres of spent wash is generated/
annum from 285 distilleries in the country, which is generally discharged
in to the water courses under untreated or partially treated conditions,
causing environmental pollution owing to its very high organic load.
In order to reduce its high biological oxygen demand (BOD) and
Chemical Oxygen Demand (COD), many distilleries recycle these effluents
to produce methane by passing them through biomethanation digesters
and the effluent thus obtained is known as Post methanation effluent
(PME)

24. Crops suitable for sewage irrigation
Fodder crops like Oats, Jowar, Maize, berseem and lucerne
Sugarcane
Vegetable crops, like Cabbage, cauliflower, turnip, potato,
brinjal, lady’s finger, beans etc.
Crops unsuitable for sewage irrigation
• Tomato
• Radish
• Onion
• Ggarlic
• Carrot and leafy vegetables

25. Current practices of recycling & reuse of Treated SewageCurrent practices of recycling & reuse of Treated Sewage
 Kolkata City raw sewage is used for agriculture andKolkata City raw sewage is used for agriculture and
pisciculture in East Kolkata Wetland (pisciculture in East Kolkata Wetland (Ramsar SiteRamsar Site))
 Treated sewage ofTreated sewage of Kalyani TownKalyani Town is used for farming to growis used for farming to grow
vegetablesvegetables
 InIn Titagarh TownTitagarh Town Partially treated sewage is used for thePartially treated sewage is used for the
growth of green vegetablesgrowth of green vegetables
 Indiscriminate sewage sludge application can disturb theIndiscriminate sewage sludge application can disturb the
soil quality especially withsoil quality especially with conjoint entry of high amount ofconjoint entry of high amount of
heavy metalsheavy metals such assuch as Cd, Ni, and PbCd, Ni, and Pb which may accumulatewhich may accumulate
in edible plant tissues and cause food chain contaminationin edible plant tissues and cause food chain contamination
((SahaSaha et al., 2015et al., 2015).).

26. Tertiary Treatment: There are many differing types of
tertiary treatment of effluents, the most common being
Grass Plots, Reed Beds, Upward flow Clarifier. Rapid
Gravity, Sand Filter, Microstrainer, Sand Filter, Drum Filter,
Lagoons, Nitrifying Filter.
Biochemical Oxygen Demand (BOD):
The amount of dissolved oxygen consumed by micro-
biological action when a sample is incubated, usually for 5
days at 20 deg. C(expressed as BOD5 ) or for 3 days at 27
deg. C (expressed as BOD3).
Chemical Oxygen Demand:
The amount of oxygen used in the chemical oxidation of
the matter present in a sample by a specified oxidising
agent under standard conditions.

27. Let the Hundred flowers bloom
pabitramani@gmail.com
http://www.bckv.edu.in