Fäkalschlammmitbehandlung als Mittel
zur Kläranlagenbetriebskostensenkung

1Projekt-Nr. 02-WA 9745/0

Treatment of Sludge from Septic Tanks in Municipal Wastewater Treatment Plants
Dipl.-Ing. Clarisse Harlay, Prack Consult GmbH,I.

GeneralPrack Consult GmbH is a consultant engineer acting world-wide a.o. in theenvironmental field. The R&D activity of Prack Consult is always close to the practiceand related to the projects Prack is working for. Prack Consult as a middle size
company often carries out its - always practice related - R&D projects with the supportof the BMBF. One of the latest project was realised in Thailand in the years 20002004: “Transfer and adaptation of sewage sludge treatment in reed beds to Thailandstandards”.
Today’s presentation deals with the R&D project “Co-treatment of faecal sludge as amean for operation cost-reduction on wastewater treatment plants”, realised between
1998 and 2001.

II.

Introduction
In 1996, the year the idea of the project was born, many millions inhabitants in theformer Eastern Germany were not connected to a central wastewater treatment plant(WWTP). Most of the wastewater was treated in septic tanks and disposed off asfaecal sludge. A connection of these inhabitants to central – state of the art wastewater treatment plants was not possible in the short to medium term. On theother side many newly built wastewater treatment plants in the new “Länder” were notworking on full loading capacity. The target of the R&D project was to close the gap
between the overproduction of poorly treated faecal sludge and not utilised treatment
capacities in central WWTPs on the other side.

III.

Treatment of sludge from septic tanks in municipal wastewater treatment plants
The R&D project was realised between 1998 and 2001 in co-operation with awastewater treatment plants building company and the Neustrelitz’s (MecklenburgVorpommern) department of works. It includes 3 main parts:-a research on the actual status of sludge treatment in Germany,-a pilot-plant test in a container wastewater treatment plant over 2 years-

an economic research.

The main results of the project are presented in the following.

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Projekt-Nr. 02-WA 9745/0

Actual status of sludge treatment in Germany
The target of the research was to review the actual situation with regards tosludge out of septic tank in former Eastern Germany and to define the frame ofapplicability for faecal sludge treatment in central municipal treatment plants,
i.e. to define the potential market for the research “results”.

In Germany the municipalities are responsible for the wastewater – thus forthe faecal sludge – disposal and treatment. This task is often transferred to awastewater operation company. The transport of faecal sludge is however for
80 % realised by third parties, the treatment of the sludge takes place in 51 %of the cases on a wastewater treatment plant of the company.

In 1998 about 5 million inhabitants or 30 % of the population of the former
Eastern Germany were not connected by pipe to central WWTPs. About 85 %of them were connected to septic tanks. Even if the connection rate to central
WWTPs still grows, in many rural area the rolling sewerage – i.e. the transportof faecal sludge in tank trucks – and co-treatment of faecal sludge in municipal
wastewater treatment plants will still be important in future.

2.

Pilot plant test
In Germany the co-treatment of faecal sludge in municipal wastewater
treatment plants is regulated in the ATV-A-123. According to this working
sheetoftheGerman

Wastewater

Association(AbwassertechnischeVereinigung ATV) each WWTP with more than 10,000 p.e. (people equivalent)
design capacity and sufficient capacities can treat up to 20 m³/d faecal sludge
per 10,000 p.e., without any analysis of the faecal sludge. The inflow should
not exceed 5 % of the wastewater inflow. As per ATV-A-123 the following
polluting loads are admitted for faecal sludge:

Parameter

UnitMin.-Value ATV

Mean Value ATV

BSB5

mg / l

500

2,500

5,000

CSB

mg / l

1,000

6,000

15,000NH4-N

mg / l

100

300

500

Ptot

mg / l

50

150

400

Table 1:

Max.-Value ATV

Polluting loads in faecal sludge as per ATV-A-123

The table shows that the concentrations have high range of value and that twodifferent faecal sludge batch can differ from 1 to 15. Compared to municipal
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3

Projekt-Nr. 02-WA 9745/0

wastewater faecal sludge is highly concentrated and has a low BSB5/CSBratio.

The aim of the R&D project was to define the limits of the co-treatment of
faecal sludge in municipal wastewater treatment plants. It was chosen to workon the Neustrelitz WWTP (designed by PC), with a capacity of 100,000 p.e.,and 3 lines. The tests were realised in 2 container-WWTP since the faecal
sludge quantities were not available for a test in the WWTP. One container
was the reference, exclusively fed with municipal wastewater. The second
container had an initial load with 85 % (of the total design capacity, expressedin volume) municipal wastewater and was fed also with faecal sludge (up to80 %).

Figure 1: Container for the pilot plant test

The main results of the test are that – under the premises of an adapted inputof faecal sludge in the WWTP all over the day – the quality of the effluent is up
to the highest request in Germany with a faecal sludge addition up to 50 % involume. A treatment of the faecal sludge alone in the container WWTP lead toan effluent quality as requested for a WWTP of small size. In short faecal
sludge can be co-treated in municipal WWTP in much higher concentration as
usually done according to the ATV-A 123, if the quality of the sludge iscontrolled beforehand.

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3.

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Projekt-Nr. 02-WA 9745/0

Economic research
Three alternatives of the wastewater treatment in rural areas – taking
Neustrelitz as an example – were investigated:-first, the treatment in septic tanks with transport of the sludge to the central
wastewater treatment plant in Neustrelitz,-in second, the connection of the population to a local sewerage and a local
WWTP with a design capacity of about 1,000 p.e.,-in third, the connection of the total population to the central WWTP
Neustrelitz over sewerage.

Taking into consideration the investment and operation costs over a period oftime of 25 years, the disposal of wastewater in septic tanks with co-treatmentof the sludge in central WWTP is the most economic variant.

For the WWTP, the co-treatment of faecal sludge – to fill not utilised existing
capacity – can lead to substantial cost reductions.

IV.

Conclusions
The co-treatment of faecal sludge can be realised in municipal WWTP at a muchhigher degree as commonly admitted in Germany, keeping the high quality of theeffluent, if the faecal sludge is added according to its quality and to the actual load of
the WWTP. This co-treatment can lead to substantial wastewater treatment costreduction (up to 0.25 €/m³).

Basing on the results of the R&D-project, Prack Consult GmbH developed a measureand control unit for faecal sludge stations on WWTP (registered utility model). Thisunit will allow a higher faecal sludge input, adapted to the existing wastewater flow
and the capacity of the wastewater treatment plant.

Prack Consult GmbH / Har

Heide, 19.09.2006

Development Consultants

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19.09.2006- 194(747_Neustrelitz/Sonstiges/060914PC747_F+E-Sludge-Neustrelitz.doc)-

- 195 Sanitary engineering

Road construction

Rundu

Prack Consult GmbH – Development Consultants

PolandKrakow, Stettin

Namibia
BangkokThailand

Murdeira / Sal

Cape VerdeInfrastructure and land development

Structural engineering

Project offices abroad

Marine and coastal engineering

Co-ordination

Head Office
Heide, Germany

Prack Consult GmbH
Development Consultants

Organisation

2Treatment of Sludge from Septic tanks in Municipal Wastewater Treatment Plants

Solid waste management

R&D Project
CompanyPresentation

Prack Consult GmbH – Development Consultants

Research on the actual status of sludge treatment inTreatment of Sludge
from Septic Tanks in Municipal
Wastewater Treatment Plants

Economic researchover 2 years

3

Pilot plant test in a container wastewater treatment plant

Germany

1Treatment of Sludge from Septic tanks in Municipal Wastewater Treatment Plants

Prack Consult GmbH – Development Consultants

III.

II.

I.

R&D Project

Prack Consult GmbH – Development Consultants

Mail: PrackConsult@t-online.dewww.prackconsult.de

Tel.: ++ 49 (481) 6 80 7-0
Fax: ++ 49 (481) 6 75 31

Lüttenheid 7925746 Heide / Germany

Prack Consult GmbH

Development Consultants, Heide

Presentation

Prack Consult GmbH

Treatment of Sludge from Septic tanks in Municipal Wastewater Treatment Plants

Development Consultants, Germany

R&D Project
Company
Presentation

Prack Consult GmbH

Treatment of Sludge from Septic tanks in Municipal Wastewater Treatment Plants„Treatment of sludge from septic tanks
in municipal wastewater treatment
plants“

R&D Project

- 196 -In central WWTPs (75 %)Agricultural utilisation (11%)
Composting (4 %)Dumping on landfill (2 %)Separate treatment plant (1 %)Prack Consult GmbH – Development Consultants-Treatment of the Sludge:

6

Treatment of Sludge from Septic tanks in Municipal Wastewater Treatment Plants

Actual Status of Sludge Treatment (1998)

R&D Project

Prack Consult GmbH – Development Consultants

Former Eastern Germany- 16 Mio. Inhabitants- 70.0 % connected to central WWTP

Former Western Germany:- 66 Mio. Inhabitants- 93.5 % connected to central WWTP

4

Treatment of Sludge from Septic tanks in Municipal Wastewater Treatment Plants

Actual Status of Sludge Treatment (1998)

R&D Project

Prack Consult GmbH – Development Consultants

7

Treatment of Sludge from Septic tanks in Municipal Wastewater Treatment Plants

Pilot Plant Test (1999-2001)

R&D Project

Prack Consult GmbH – Development Consultants- Cesspools- Septic tanks- Small WWTP without sludge treatment

Origin of the sludge:

5

Treatment of Sludge from Septic tanks in Municipal Wastewater Treatment Plants

Actual Status of Sludge Treatment (1998)

R&D Project

> 10,000 p.e. design capacity
Sufficient capacity
20 m³ per 10,000 p.e.
< 5 % of wastewater inflow

Prack Consult GmbH – Development Consultants-Boundary conditions for the co-treatment ofSludge in WWTP:

10Treatment of Sludge from Septic tanks in Municipal Wastewater Treatment Plants

Pilot Plant Test (1999-2001)

R&D Project

Prack Consult GmbH – Development Consultants

8Treatment of Sludge from Septic tanks in Municipal Wastewater Treatment Plants

Pilot Plant Test (1999-2001)

R&D Project

FS-AS

VF 25

VB

VF
40

SF KA-NZ

VF
32

BB 2

C-KLA 2

NK 2

SS 2

mg / lmg / lmg / l

COD
NH4-N
Ptot

50

100

1,000

500

150

300

6,000

2,500

400

500

15,0005,000

Min.-Value
Mean
Max.ATV
Value ATV Value ATV

Prack Consult GmbH – Development Consultants

mg / l

BOD5Unit

Polluting loads in Faecal Sludge
as per ATV-A- 123:
Parameter

E2

KA-NZ

9KA-NZ

11

Treatment of Sludge from Septic tanks in Municipal Wastewater Treatment Plants

C-KLA 1

NK 1

Pilot Plant Test (1999-2001)

R&D Project

Prack Consult GmbH – Development Consultants

AWFS

BB 1

SS 1

Treatment of Sludge from Septic tanks in Municipal Wastewater Treatment Plants

Pilot Plant Test (1999-2001)

R&D ProjectE1- 197 -- 198 -

050

100

150

200

250

300

BOD

COD

Norg

NH4PO4TSpH

12- Connection of the population to a local WWTP

- Not sufficiently treated sludge

Prack Consult GmbH – Development Consultants- Treatment in cesspools with transport of sludge
to a central WWTP

- Central wastewater treatment plants with freetreatment capacities

Prack Consult GmbH – Development Consultants- Connection to a central WWTP

Approach:

15

Treatment of Sludge from Septic tanks in Municipal Wastewater Treatment Plants

Economic research

R&D Project

Prack Consult GmbH – Development Consultants- Sole treatment of faecal sludge leads to effluent
quality as requested for small WWTP (up to1,000 p.e.)- Co-treatment of up to 50 % Sludge (in vol.) witheffluent quality up to highest German Standards

Results of the tests:

13

Treatment of Sludge from Septic tanks in Municipal Wastewater Treatment Plants

Pilot Plant Test (1999-2001)

R&D Project

Why:

14

Treatment of Sludge from Septic tanks in Municipal Wastewater Treatment Plants

Economic research

R&D Project

Ptot

Parameter

No3

Mean concentrations in Faecal Sludge (compared to municipalwastewater = 100 %)Prack Consult GmbH – Development Consultantsvalue]

Faecal sludge and wastewater:

LF

Treatment of Sludge from Septic tanks in Municipal Wastewater Treatment Plants

Pilot Plant Test (1999-2001)

R&D Project

Faecal Sludge concentration [%-- 199 -- Septic tanks, transport to and treatment of thesludge in a central WWTP is the most economicsolution- Transport costs

Prack Consult GmbH – Development Consultants- Reduction of the costs through acceptance andtreatment of much higher quantities of faecal
sludge – only possible with a proper faecal
sludge management

For central WWTP:

Results:

18

Treatment of Sludge from Septic tanks in Municipal Wastewater Treatment Plants

Economic research

R&D Project

Prack Consult GmbH – Development Consultants

Thank you foryour attention

Development Consultants, Germany

Prack Consult GmbH

Treatment of Sludge from Septic tanks in Municipal Wastewater Treatment Plants

Prack Consult GmbH – Development Consultants

R&D Project

Prack Consult GmbH – Development Consultants

For regions with a low density of population- Investment costs for the treatment capacity, thesewer and the transport mains- Operation costs

Results:

17

Treatment of Sludge from Septic tanks in Municipal Wastewater Treatment Plants

Economic research

R&D Project

Approach as per LAWA:

16

Treatment of Sludge from Septic tanks in Municipal Wastewater Treatment Plants

Economic research

R&D Project