Sanitation

Wastewater

Water and Sanitation

Residential Wastewater
flushing systems with

centralized treatment
decentralized treatment

dry systems, mainly decentralized managed, like

pit latrines
dry toilets

Residential Wastewater: Fractions

Black Water: Waste water from Toilettes and Urinals
Brown Water: Feces, with or without water
Yellow Water: Urine from Urinals or Separation toilettes, with or without water
Grey Water: Waste water from Kitchen, Bath, Washing etc .

Pathogen distribution across the different streams
Faeces:

Contains most of the pathogens
Exposure to untreated faeces is considered unsafe

Urine:

Low health risk (only a few diseases transmitted through urine)
Risk of faecal cross-contamination

Grey Water:

Low health risk
Contamination through laundry, washing diapers, from foodstuffs
Lower risk of faecal cross-contamination

Source: Sandec Training Tool

Decentralized Sanitation

Decentralized/Pit Latrines

collect human feces/urine in a hole
liquids seep into the ground
Exception -> fully lined pit latrines

While one pit is in use, the other one is closed.
The system consists of:

2 pits
2 pieces to reinforce the pits
1 concrete slab (movable)
1 toilet house (movable)

Recommendations

installation in reasonable distance from house
avoidance contact to collected material, emptying the pit regularly
faecal sludge management essential
- transport
- treatment
- usage

Decentralized/Urine diversion Toilets/Ecosan

Stabilization Ponds
Combination of:

anaerobic ponds
- TSS settles
- dissolved C -> anaerobic digestion
facultative Lagoon
- O2 only at the surface
- BOD removal -> bacteria -> oxygen from photosynthesis of algae
- shallow , large surface
  - high sunlight radiation
  - high atmospheric O2 dissolve
- sediment layer
maturation ponds
- aerobic conditions
- removal of pathogens/nutrient reduction aerobic bacteria
- shallow , large surface
  - high sunlight radiation
  - high atmospheric O2 dissolve

Summary Stabilisation Ponds:

can be made and repaired with local materials
no real problem with odors and flies if designed properly
low operating costs
no electricity required
requires expert design and supervision
requires large land area
Sludge require secondary treatment and appropriate discharge
removal of -> pathogens, worms and helminth eggs
not suitable in areas where stringent discharge standards exist -> additional stages of post treatment necessary

WHO (2006). WHO Guidelines for the Safe Use of Wastewater, Excreta and Greywater - Volume IV: Excreta and greywater use in agriculture; R. Schertenleib et al.: Compendium of Sanitation Systems and Technologies, eawag

Constructed Wetland
Pretreatment

settling pond ≥1.5 qm/Person
multi chamber septic tank ≥ 300l/Person
raw wastewater filter ≥ 1.2 qm/Person

Main Treatment

vertical reedbed filter ≥ 4 qm/Person
horizontal reedbed filter ≤ 100 g COD/cbm*day

Post treatment > 1qm/Person

Source: Arbeitsblatt DWA-A 262, 2017

Decentralized Technical WWT Plants like:

Fixed Bed Reactor
Moving Bed Reactor
Membrane Bioreactor
Trickling Filter
Sequency Batch Reactor
Activated Sludge Reactor
Upstream Anaerobic Sludge Bed Reactor
Aerated Wetlands

Urine Utilization
Pathogenes

Urine:
- mostly free of pathogens,
- but risk of cross-contamination through faeces
Recommendation before use:
- Urine storage (in an airtight container)
  - degradation of urea to ammonia leads to
    - pH increase (to around 9)
    - pathogen reduction
Further inactivation of pathogens is expected in the field between time of fertilization and consumption
Storage also important as the use of the urine as a fertilizer on farmland is only possible during the two short planting seasons per year.

Storage of urine for pathogen reduction

Urine collected from individual households and used for the household’s own consumption:
- suitable for fertilizing all types of crops if one month is allowed between fertilization and consumption

Source: Caroline Schönning: Urine diversion – hygienic risks and microbial guidelines for reuse (for WHO)

Urine application

Urine dilution before use:
1 part of urine to 2-5 parts of water depending on soil fertility and plants
Application: the diluted solution is sprinkled around the plants/crops in the root zone for plant uptake
Due to high N-concentrations, urine is especially good for crops which normally are very limited by the supply of nitrogen

Sludge treatment

Surface disposal: Stockpiling of sludge that cannot and will not be used elsewhere
Land application: Depending on the sludge quality, application to public or private lands
- agriculture
- landscaping
Composting: General definition: Stabilized sludge is also referred to as ‘Biosolids’.
- Compost: product of controlled aerobic degradation of organics into a soil-like substance
- Humus: material removed from an alternating pit, produced passively underground
- Co-Composting: controlled aerobic degradation of organics using more than one feedstock:
  - Faecal sludge: high moisture and nitrogen content
  - Biodegradable solid waste: high in organic carbon and good bulking properties (i.e. it allows air to flow and circulate)
Sedimentation / Thickening tanks: Settling ponds that allow the sludge to thicken and dewater. The effluent is removed and treated, while the thickened sludge can be treated with a subsequent technology.
Unplanted drying beds:
- simple, permeable bed with collection of leachate (50% to 80% of the sludge volume drains off as liquid)
- sludge drying by evaporation, however sludge is not stabilized
Planted drying beds:
- Similar to an unplanted drying bed with increased transpiration
- Key feature: Fresh sludge can be applied directly onto previous layer; the plants and their root systems maintain the porosity of the filter
Anaerobic digester: anaerobic treatment technology that produces:
- a digested slurry ► soil amendment
- biogas ► energy

Source: R. Schertenleib et al.: Compendium of Sanitation Systems and Technologies, eawag, http://doc.rero.ch/record/309484/files/12-13._Compendium_2nd_Ed_Lowres_EN.pdf

For more information:

2017 UN World Water Development Report, Wastewater: The Untapped Resource
http://www.unesco.org/new/en/natural-sciences/environment/water/wwap/wwdr/2017-wastewater-the-untapped-resource/

The United Nations World Water Development Report 2019
http://www.unwater.org/publications/world-water-development-report-2019/

http://sswm.info/sites/default/files/reference_attachments/EAWAG%20SANDEC%202008%20Module%204%20Sanitation%20Systems%20and%20Technologies%20-%20Presentation.pdf

http://www.who.int/water_sanitation_health/monitoring/coverage/monitoring-dwater/en/

Water Use

Water Stress:

lead to an awareness about water resources and how to provide enough water for use worldwide

Drivers for Water Reuse

Need for new/additional water supplies for drinking and other purposes (mainly irrigation)
Need to leave high quality water sources for drinking purposes
- Reclaimed water for other purposes than drinking
Reuse of nutrients
Amount of reclaimed water is less subject to seasonal fluctuations
Costs of drinking water are increasing

Water Sources for Water Reuse e.g.
Wastewater: Wastewater from any kind of residential source
Greywater: Wastewater from kitchen, bath, washing, laundry etc.
Process Water: Industrial process water, e.g. cooling water, wash water

Relevant Parameters for Reuse Purposes
Microbiological:

Bacteria
Viruses
Worms
Protozoe

Chemical:

Organic parameters (incl. anthropogenic organic trace substances, Nanoparticles (1 – 100 nm))
Inorganic parameters (TDS)

Physical-chemical characteristics:

pH (alkaline, acid), Temperature
Electrical conductivity
Oxygen

Sensorial:

Color, Odor, Foam
Taste
Turbidity

Anthropogenic Organic Trace Substances

pollution groups -> are mainly made by products of daily use
e.g. body care products, hormones, fire retardants, plasticisers, pesticides, industrial additives and aids

Barriers for Water Reuse
Risk Barriers:
Contaminants in Recycled Water

Medicaments
Microplastic
Heavy metals
Pathogens, Worms
-> Health Risk
-> Contamination of soil or groundwater resources

User Barriers
Water Reuse

Avoidance/Cultural Reasons
risky for User/Consumer if used for:
- Irrigation
- Food Production
- Aquifer Recharge
more expensive?

Acceptance
Information -> Awareness
Quality Guarantee -> Sufficient Treatment
Control -> Monitoring

Major applications for water reuse

1. Agricultural use: Crop irrigation, aquaculture
2. Landscape irrigation: Parks, play grounds, etc.
3. Industrial use: Cooling water, process water, dust control, concrete curing, etc.
4. Non-potable urban uses: fire protection, toilet flushing, commercial car washing
5. Groundwater recharge: replenishment, saltwater intrusion control
6. Potable reuse:
indirect: blending with public water supplies (surface water or groundwater)
direct: pipe-to-pipe water supply after treatment

International Standard for Irrigation
ISO 16075 “Guidelines for treated wastewater use for irrigation projects“ in 4 parts:
1) The basis of a reuse project for irrigation
2) Development of the project
3) Components of a reuse project for irrigation
4) Monitoring
-> improved irrigation

Irrigation

Subsurface irrigation
Surface irrigation
- flush/flood irrigation, furrows
- sprinkling irrigation
- micro irrigation (drip irrigation)

But, no irrigation without drainage!!! Problems with irrigation caused by:
water run off -> soil Erosion
evaporation -> salinization
silting -> clogging
dammed water -> plants cannot grow (except rice)

Furrow Irrigation
parallel channels along the field length

in the direction of predominant slope
water is applied to the top end of each furrow
flows down the field under the influence of gravity
distance of furrows -> space depends on crop species

speed of water depends on:

soil infiltration rate
slope
inflow rate
design of ground

Aquaculture
Controlled cultivation of aquatic plants or animals or both.
Modified maturation pond

Filtration in the roots area
Uptake of remaining nutrients from treated wastewater

Aquifer Recharge
Intentional recharge of water (treated surface water or treated waste water) to suitable aquifers for subsequent recovery

Aquifer Recharge Systems for treated wastewater
recharge basin:

infiltration pond
lagoons

Injection well:

into the vadose zone
directly into the aquifer

Reuse of Residential Greywater
direct discharge into ponds could be critical
►risk of eutrophication
►bad smell

direct reuse:

for irrigation of plants, trees
(not recommendable for fruits etc.,
risk of introducing pathogens)

reuse after treatment for:

washing
toilet flushing
garden watering
irrigation

-> depending on water quality

Rain Water

Simple Water Cycling Tips
Bath Water:

Harvest rainwater from roofs into a tank
Use it for bathing or washing

Irrigation:

Use rainwater to grow food

Cooling:

Place trees on the east and west sides of a building to cool air instead of using air conditioning
Source: Brad Lancaster: Rainwater Harvesting, 2014

Precipitation:

can occur as rain, hail, sleet and snowfall
is the primary source of fresh water
is naturally distilled through evaporation prior to cloud formation

Source: Brad Lancaster: Rainwater Harvesting, 2014

Rainwater Harvesting
benefits of rainwater:

is soft due to the lack of calcium carbonate or magnesium in solution
is excellent for cooking, washing, watering
is free of charge

Source: Brad Lancaster: Rainwater Harvesting, 2014

Collection of Rainwater consider:

the local rainfall pattern
the size of the collection surfaces
the surface’s materials and their drainage characteristics
sizing and material of piping systems
the levels of pollution of the collection surface
the risk of contaminating the system

Source: DIN EN 16941-1: 2018

Rainwater Pollution

Runoff from divers dispersed sources:

Waste storage
Roofs
Motor vehicle emissions
Cleaners, detergent
Animal feces
Sediment, pesticides, fertilizer
Yards, farms → Nitrogen

Source: Brad Lancaster: Rainwater Harvesting, 2014

Collecting Rainwater
Impact of quality depending on the surfaces:

green roof -> coloration
bitumen containing material -> coloration, tar
cement with fibres -> emission of fibres in the long term
copper, lead or zinc roofs -> increased concentrations of heavy metals

Source: DIN EN 16941-1: 2018

Water Conservation Strategies at Home

No swimming pools – use community pools
Plumbing leaks – repair them
Washing machines which use less than 38L per load of wash
Rainwater for toilet flushing
Reduce water consumption
Only natural outdoor misting systems
Greywater and Rainwater Use at Home

Source: Brad Lancaster: Rainwater Harvesting, 2014

Treatment of Rainwater
1. removal of coarse particles upstream of the storage
2. retention of fine particles by sedimentation and flotation in the storage device
3. Filtering downstream of the storage device, depending on the intended use
-> Disinfection, deodorization, discoloration may be required additionally
Source: DIN EN 16941-1: 2018

Storage of Rainwater
The storage device shall be protected against…..

frost,
extreme temperatures
direct sunlight,

measure -> e.g. buried underground
The structural behavior shall be taken into account when positioning the storage device.
Source: DIN EN 16941-1: 2018

Distribution of treated Rainwater
The treated rainwater/non-potable water shall be distributed by:

pumping from the storage device directly to the point of use
pumping from the storage device to an intermediate cistern/tank near the point of use
using a gravity cistern
using a full gravity system.

Source: DIN EN 16941-1: 2018

Rainwater Harvesting Principles for Lands
1. Begin with long and thoughtful observation.
2. Start at the top of your watershed and work your way down.
3. Start small and simple.
4. Spread and infiltrate the flow of water.
5. Plan for an overflow route, and manage that overflow water as a resource.
6. Maximize living and organic groundcover.
7. Continually reassess your system: the “feedback loop”.
Source: Participatory Ecological Land-Use Management association of east and southern Africa and Mr. Zephania Phiri Mnaseko and other water harvesters. From: Brad Lancaster: Rainwater Harvesting, 2014

Water Conserving Techniques