Liquid Waste management Date: 13 March 2018

Liquid Waste (Any waste that is in liquid form)

Improper disposal of liquid waste leads to

Pollution of water bodies

Pollution of groundwater

Breeding of mosquitoes, bad odour

Spreading of diseases

Deterioration in the aesthetic beauty of places

Liquid waste classification

Liquid waste

Domestic

Sewage Sullage

Industrial

Effluent from industrial process

Eg: effluent from municipal markets, slaughter houses and industrial

process

Sewage

• Black water - Mixture of Urine, Faeces and flush water (35% of total wastewater

• Grey water - Water generated from Kitchen, washing of clothes, bathing water and floor cleaning water (65% of total wastewater

• Sewerage - Pipe network carrying sewage

Wastewater Characteristics

• BOD – measure of biodegradable organics, approximate quantity

of oxygen required for biological stabilisation of the organic matter

• COD – measure of quantity of oxygen required for stabilizing biological as well as chemical pollutants

• TSS – Total suspended solids

• Faecal Coliform – Indicator bacteria for pathogens

Before and after Wastewater treatment (taken sewage as the wastewater)

Characteristics Before treatment After treatment

pH 5.5 - 9 6.5-9

BOD 250-300 mg/l <30 mg/l

COD 600 mg/l <250 mg/l

TSS 200 mg/l <100 mg/l

Faecal coliforms

106 MPN/100 ml <1000 MPN/100ml

* The concentration of contaminants in industrial wastewater could be higher than that of

Sewage. The characteristics of treated effluent should conform to the regulatory authority

Wastewater treatment Chain

Primary treatment

(Physical Process)

• Removal of solids

• Screen

• Grit chamber

• Primary settlers

Secondary treatment

(Biological Process)

• Removal of organic content

• Anarobic process

• Aerobic process

Tertiary Treatment

(Chemical/Pholtolytic process)

• Disinfection – pathogen removal

• Chlorination

• Ultra violet

Screens Grit removal Primary settler

Biological process

Secondary settler Filtration Disinfection Treated water

Sludge drying bed

Typical Sewage treatment flow chart

Wastewater

Sewage management systems

Sewage management

models

Centralised treatment

(eg: Muttathara sewage treatment plant in TVM)

Decentralised treatment

(Institutional level)

Sewage Treatment Systems

Centralised treatment

High capital cost

Not suitable for high water table area

Practical difficulty in sewerage laying

Project implementation time longer (3-5 years)

Reduces reuse of treated resources

Decentralised treatment

Treatment systems at institutional level or treatment systems for small population

Less capital cost

Project implementation time short (6 months-1 year)

Allows segregation wastewater streams and encourage reuse options

Decentralised treatment (Institutional level)

• Hospitals

• Educational institutions

• Municipal markets

• Slaughter houses

• Residential Apartments (Having more than 300 residents)

• Large office complexes

• Recreational water theme parks

• Industries

Wastewater management in Institutions

Selection of wastewater treatment systems

Quantify the amount of wastewater to be treated (usually 80% of the water demand)

Assess the characteristics of wastewater in accredited laboratories (BOD, COD, pH, TSS, Faecal coliform content)

Assess the nature of soil and groundwater table in the area

Depending on the Wastewater characteristics and site specific conditions treatment process are selected

Land area available and amount of money also affects treatment configuration

Wastewater Quantification guidelines (ref: CPHEEO manual)

No Institutions Water Supply (litres/day)

1 Hospital including laundry and beds exceeding 100 450 per bed

2 Hospital including laundry and beds not exceeding 100 340 per bed

3 Lodging houses/hotels 180 per bed

4 Hostels 135 per person

5 Nurses homes and medical quarters 135 per person

6 Boarding schools/Colleges 135 per person

7 Restaurants 70 per seat

8 Airports and Seaports, duty staff) 70 per person

9 Airports and Seaports, alighting and boarding persons 15 per person

10 Train and Bus Stations, duty staff 70 per person

11 Train and Bus Stations, alighting and boarding persons 15 per person

12 Day Schools/colleges 45 per person

13 Offices 45 per person

14 Factories, duty staff 45 per person

15 Cinema, concert halls and theatres 15 per person

Onsite sanitation systems in public institutions (Educational Institutions, Offices etc)

• Septic tanks – Assessment of existing septic tanks, septic have a soak pit?, Water tight?

• 3 R’s - Reduce (can we reduce the amount of water used?, fixing of leaks in taps, flushes etc

- Recycle (Rain water harvesting

- Reuse (Is there any scope of greywater reuse. If grey water is seperated from black water, greywater can be treated inexpensively and use for agriculture, flushing, floor cleaning and toilet washing.)

Wastewater stagnation

On-site wastewater treatment options

1. Greywater treatment systems (as the BOD and COD is lesser than blackwater these systems may not be expensive)

Septic tanks

Grey water

Planted Gravel filter Disinfection

Treated water

2. Greywater Piped root zone irrigation or Soak pit

Decentralised wastewater treatment plants

Septic tank soak pit system can be used for habitats containing up to 300 users

In hospitals the water demand is more than domestic settings

Proposed wastewater plants in LSGIs (to be constructed)

a) Sewage treatment plant in Taluk hospital Sultanbethery

b) Sewage treatment plant in Govt. Ayurvedic Hospital Porakkattiri

c) Wastewater treatment plant in municipal markets Kottakkal and Kanjangadu municipalities

d) Sewage treatment plant in Vadakara Jilla Hospital

Thalipparambu Municipality (wastewater treatment plant)

Faecal Sludge management for onsite sanitation systems

• Majority of households in Kerala use Septic tanks/pits

• Faecal sludge – Waste collected from Septic tanks/Pits

• Faecal sludge collected by vaccum trucks and dumped into water bodies, barren land and drains causing environmental pollution

• Solution to this problem?

Septage treatment plants serving group of Block Panchayats

Eg: Two Septage Treatment plants in Eranakulam district (Brahmapuram and Wellington Island)

Soil conditioner and clean water for agriculture from Septage treatment

Septage Treatment plant in Brahmapuram

Use/Disposal of treated water and sludge

Useful Products from sewage treatment

Organic manure (soil conditioner) from sludge

Treated water for agriculture, construction purposes, toilet flushing, floor and toilet washing etc.

Biogas can be used for cooking or used to make electricity

Disposal of treated water through soak pits, to water bodies or drains

Model for proper wastewater treatment and reuse in non-sewered areas

Faecal Sludge treatment plants

Decentralised treatment plants

Main points

• Systems should be developed for greywater management in institutions where there is an onsite sanitation such as septic tanks

• Liquid waste treatment systems should be implemented in educational Institutions with hostel facilities, hospitals, markets, apartments and slaughter houses

• Treated water reuse for non-potable uses must be encouraged

• Faecal sludge treatment plants for treating septage waste

• Compost production from septage

Thank You