G E R M A N A T V S T A N D A R D S

W A S T E W A T E R - W A S T E

ADVISORY LEAFLET ATV-M 273E

Feeding and Introduction of Residual Matter from Water Supply Facilities into Wastewater Facilities

August 1999

ISBN 3-935067-38-0

Obtainable from:

GFA Verlag e.V. the Publishing Company of ATV-DVWK - Wastewater, Waste

and Water Management

Theodor-Heuß-Allee 17, D-53773 Hennef

Telephone: ++49-2242/872-120, Telefax: ++49-2242/872-100

E-mail: lumma@atv.de - Internet: http://www.gfa-verlag.de

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Preparation This Advisory Leaflet has been elaborated by the ATV Working Group 2.3.2 "Waterworks Sludge" within the ATV Specialist Committee 2.3 " Discharge of Wastewater from Commercial and Industrial Concerns into a Public Wastewater Facility".

ATV Working Group 2.3.2 "Waterworks Sludge" has the following members:

Dr.-Ing. Dieter Bergmann, Dresden, (Chairman) Dr.-Ing. Eckhard Dammann, Hamburg Dipl.-Ing. Bernd-Rüdiger Dries, Forchheim Dr.-Ing. Predrag Ilic, Frankfurt Dipl.-Ing. Rainer Ließfeld, Bonn Dipl.-Chem. Ferdinand Sarfert, Berlin Dipl.-Ing. Karl Sichler, Erlangen Dipl.-Ing. Wolfram Such, Siegburg (Vice-Chairman) Prof. Dr.-Ing. Knut Wichmann, Hamburg

The following has collaborated as guest: Dipl.-Ing. Silke Asmussen, Hennef

All rights, in particular those of translation into other languages, are reserved. No part of this Advisory Leaflet may be reproduced in any form by photocopy, microfilm or any other process or transferred or translated into a language usable in machines, in particular data processing machines, without the written approval of the publisher.

GFA -Publishing Company of ATV-DVWK - Wastewater, Waste and Water Management, Hennef 1999

Original German Edition produced by: DCM, Meckenheim

Contents

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Preparation 2

Notes for Users 4

Foreword 4

1. Scope, objective, purpose 5

2. Terms, Definitions 6 2.1 Public water supply facilities 6 2.2 Public wastewater facilities 6 2.3 Residual matter 6 2.4 Wastes 6 2.5 Wastewater 6 2.6 Water containing sludge 7 2.7 Sludges 7 2.8 Dewatered sludge 7 2.9 Clarified water 7 2.10 Feeding into wastewater facilities 7 2.11 Introduction into wastewater facilities 7

3 Type and source 7

4 Composition 8

5 Possible effects with feeding and introduction 10

6 Notes for the usage of residual matter containing iron 11

7 Prerequisites and technical possibilities 13 7.1 General prerequisites 13 7.2 Feeding into the sewer system 14 7.3 Feeding and/or introduction into wastewater treatment facilities 14

8 Notes on economy 15

9 Checklists 16 9.1 Details on the waterworks 17 9.2 Checklists for the wastewater facilities operator(s) 20 9.2.1 Sewers, pumping stations, elevators 20 9.2.2 Wastewater treatment facilities 21

10 Summary assessment 23

Literature 24

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Notes for Users This ATV Advisory Leaflet is the result of honorary, technical-scientific/economic collaboration which has been achieved in accordance with the principles applicable for this (statutes, Rules of Procedure of the ATV and ATV Standard ATV-A 400). Here, according to precedents, there exists an actual presumption that it is textually and technically correct and also generally recognised.

The application of this Advisory Leaflet is open to everyone. However, an obligation for application can arise from legal or administrative regulations, a contract or other legal reason.

This Advisory Leaflet is an important, however, not the sole source of information for correct solutions. With its application no one avoids responsibility for his own action or for the correct application in specific cases; this applies in particular for the correct handling of the margins described in the Advisory Leaflet.

Foreword The feeding and introduction of residual matter from water supply facilities into wastewater systems have, in numerous cases in the past, been well proven. It has been known for a long time that, with a defined dosing of the waterworks residual matter - into a sewer or into a wastewater treatment system - operational advantages can result with the disposal of wastewater. The modified water and waste general legal regulations nevertheless no longer allow this disposal route to be based essentially on an agreement between water supplier and wastewater disposer, but demand for this the fulfilment of numerous criteria.

Insofar as the legal and technical prerequisites are met, the disposal of waterworks residual matter through the feeding or introduction into wastewater systems can often still be an economically cost-effective solution. Therefore it is a priority task of the DVGW - Deutscher Verein des Gas- und Wasserfaches e.V (German Association for Gas and Water) - and the ATV-DVWK - Vereinigung für Abwasser, Abfall und Gewässerschutz e. V (German Association for Water, Wastewater and Waste), through a common Advisory Leaflet, so to regulate the feeding and introduction of residual matter from water supply facilities into wastewater facilities, that ecologically and economically sensible solutions apply. With this, for the operator of a wastewater facility, above all with the matching and optimising of existing engineering systems, it can concern possible consequences for the waterworks operator through the employment of other operating material, or appropriate processing technology to match the properties of the residual matter to the requirements of the wastewater disposer.

In this Advisory Leaflet arguments and facts are combined which make it possible for both the waterworks operator and the operator of the wastewater facility to consider the advantages and disadvantages from the respective points of view and to find a common platform for this disposal route. Technical questions with the employment of waterworks residual matter in wastewater facilities are described and operational effects with the disposal of wastewater are demonstrated so that appropriate constraints for the acceptance of waterworks residual matter by those responsible for the disposal of

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wastewater can be laid down, taking into account disposal safety for the water supply facility and the process-technical operating safety for the wastewater facility.

The legal admissibility of the disposal of waterworks residual matter in municipal wastewater facilities has been presented at the start by an ad hoc working group "Questions of Legal Demarcation Wastewater - Waste" made up from members of the DVGW and the ATV-DVWK. The result is published as the ATV Report " Disposal of Waterworks Residual Matter in Municipal Wastewater Facilities - Prerequisites for Admissibility under Water Law and Waste Law" in the Korrespondenz Abwasser [16] and, in abbreviated form, in the gwf [17].

ATV Advisory Leaflet ATV-M 273 has passed through the public participation procedure in accordance with ATV Standard ATV-A 400. Due to the existing objections publication as an ATV Standard has been dropped, with the result that, due to its rather recommendatory character, it is published as an Advisory Leaflet.

The Advisory Leaflet is published, with the same technical text, under the number W 222 within the DVGW Rules and Standards.

1 Scope, Objective, Purpose This Advisory Leaflet applies for the disposal of residual matter from facilities within the public water supply system (waterworks residual matter) in public wastewater facilities. It can also apply analogously for the disposal of similar residual matter from non-public water supply systems into non-public wastewater facilities.

The scope of the advisory leaflet covers the disposal of solid and liquid waterworks residues. With this, both the immediate utilisation of residual matter in wastewater facilities and also a joint disposal together with residual matter from wastewater treatment are included.

Through the feeding or introduction of residual matter, the water quality and the possibilities for the disposal of sewage sludge are not to be jeopardised illegally. Based on this principle, the essential technical prerequisites, which are available or which must be created, are described in this advisory leaflet, so that this requirement can be met. The advisory leaflet contains details on the type, source and composition of the waterworks residual matter. The technical possibilities for the feeding and introduction of residual matter as well as the possible effects on the operation of the wastewater facilities are also described. For costs determination there is information which enables a cost-based assessment of this disposal route to be made. With the help of checklists the necessary details and parameters for a possible feeding/introduction of waterworks residual matter into wastewater facilities can be ascertained and thus the suitability of the disposal possibility can be checked and the disposal route can be traceably documented.

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With regard to the legal prerequisites for the disposal of waterworks residual matter into wastewater facilities, attention is drawn to the ATV Report "Disposal of Waterworks Residual Matter in Municipal Wastewater Facilities - Prerequisites for Admissibility under Water and Waste Law" [16] and DVGW Standard W 221-1 [3].

The application of the available advisory leaflet does not replace examination of the individual case. This examination is to take place in close collaboration between the operators of water supply systems and wastewater facilities; if required the responsible authorities are to be involved. With this, the examination can lead to a pre-treatment of the waterworks residual matter becoming practical or necessary. For this attention is drawn to DVGW Standard W 221-2 [3]. If the examination shows that disposal in the wastewater facility is not possible or not practical, other disposal routes are to be selected for the waterworks residual matter. Attention is drawn to DVGW Standard W 221-3 for this.

2 Terms, Definitions 2.1 Public Water Supply Facility

Within the meaning of this advisory leaflet as part of the public water supply facility is any system provided for the extraction, processing, storage and distribution of water for the supply of the general public.

2.2 Public Wastewater Facility

Considered as a public water supply facility is any system provided to the general public for the collection, discharge, treatment or disposal of wastewater as well as for the treatment of sewage sludge in connection with wastewater disposal.

2.3 Residual matter

Residual matter from water supply facilities are those unavoidable resultant substances with water processing and distribution which cannot be returned into the preparation process or be marketed as a by-product [3]. They must, therefore, be disposed of.

2.4 Wastes

In accordance with the legal waste regulations, all residual matter even if it can be utilised is designated as waste, insofar as is not wastewater.

2.5 Wastewater

Liquid residual matter is wastewater within the meaning of water law as soon as it is discharged into a wastewater facility.

2.6 Water Containing Sludge

Designated as water containing sludge is water produced during water processing which contains solid matter. For example water from the flushing of filters.

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2.7 Sludges

Within the meaning of this Advisory Leaflet, sludges are the still free-flowing solid/water mixtures in which the undissolved substances are enriched following sedimentation, flotation or thickening of water containing solid matter.

2.8 Dewatered Sludge

Dewatered sludge is sludge from which water is removed, using natural or mechanical processes, such that, in general, it is no longer free-flowing.

2.9 Clarified Water

Designated as clarified water is water which is extensively free of solid material resulting from water containing sludge and sludge with water being separated in settling tanks, thickeners or flotation plants,

2.10 Feeding into Wastewater Facilities

Feeding into wastewater facilities is the delivery of water containing sludge and sludge

2.11 Introduction into Wastewater Facilities

Introduction into wastewater facilities is the delivery of dewatered sludges and solid residual matter

3 Type and Source Groundwater and surface water, dependent on source, contain various quantities of dissolved and undissolved matter of natural or anthropological origin. Dissolved, suspended and collodial matter of inorganic and organic origin as well as dissolved gases whose type, quantity and characteristics are determined by the properties of the raw water, are removed using various processing procedures.

With the processing of drinking water there are content substances to be removed which, from a hygienic aspect, are undesirable or can cause technical problems such as depositing, colouring or corrosion in the distribution network. The processing of process water for commercial, industrial, agricultural or similar purposes serves for the removal of substances from the raw water to fit its characteristics to the respective utilisation purposes and to certain requirements.

Here, only the specific residual matter from water processing and distribution systems are gone into in detail. The type and properties of the other residual matter from other water supply facilities such as laboratories, workshops, test centres, recreational facilities for operational and administrative personnel etc. do not vary from those from other branches. They are not dealt with in this advisory leaflet.

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The main types of residue from water supply facilities are listed below:

• residual matter from flocculation using aluminium compounds • residual matter from flocculation using iron compounds • residual matter from deferrisation and demanganising • residual matter from water softening and decarbonisation • residual matter from adsorption using active carbon • residues from desludging, cleaning and flushing of water containers and dosing,

mixing, conveying and transport facilities • residual matter from preliminary treatment (sieving, sedimentation) • residual matter from sandwashing with slow-speed sand filtration and percolation

So far as these residues are disposed of as waste they are to be declared in accordance with the ordinance for the of the European Wastes Catalogue (EWC Ordinance) dated 13 September 1996 (BGBl.1 p. 1428 [13].

4 Composition Water containing sludge is mainly yielded as residual matter from the various treatment stages with the processing of groundwater and surface water.

The properties of the residual matter to be disposed of are influenced by the substances removed from the treated water, the processing method employed and the chemicals used with this.

The material composition of the substances, which varies according to the origin of the water to be processed and according to the processing method applied, influences to a considerable extent the physical and, inter alia, also the mechanical characteristics of the residual matter.

The main components of the important residual matter from water processing are listed as an example in Table 1.

In addition, undesired ancillary components such as, for example, halogenised organic compounds, measured as AOX, heavy metals or others (e.g. arsenic) can be contained, which, with feeding/introduction into the wastewater facility, can acquire significance. In the case of application an analysis of the relevant content substances should be presented by the waterworks for closer assessment (comp. checklist in Chap. 9.1).

With assessment with regard to an agricultural utilisation of sewage sludge the guidance values of ATV Standard ATV-A 202 " Procedures for the Elimination of Phosphorus from Wastewater", Table 2 are to be observed [18].

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Table 1: Main components of various residues from water processing (examples)

Residual matter from: Parameters Share of dry mass mT (in %)

CaCO3 78 Fe2O3 •1.5 H2O 13

Softening/decarbonisation 1)

Humic matter 6) 6 Fe2O3 • 1.5 H2O 60 CaCO3 9 MnO2 4

Deferrisation/demangenising 2)

Humic matter 6) 18

Fe2O3 • 1.5 H2O 51 Al2O3 • H2O 3 Acidic insoluble matter 19

Flocculation using Fe compounds 3)

Organic components 6) 22

Al2O3 • H2O 35 Fe2O3 • 1.5 H2O 8 Organic components from natural lake sediments

35

Inorganic components from natural lake sediments

10

Flocculation using Al compounds 4)

CaCO3/CaSO4 3

Al2O3 • H2O 10 CaCO3 10 CaSO4/Ca3(PO4)2 8 Fe2O3 • 1.5 H2O 5 Organic suspended matter from the flowing wave

22

Flocculation using Al compounds and from the sandwash 5)

Inorganic suspended matter from the flowing wave

40

1) Example of a typical combination of residual matter from the softening decarbonisation of groundwater in Northern Germany. Residual matter of this type from other waterworks can also contain considerable parts of Mg(OH)2 or acidic insoluble matter.

2) Example of a typical combination of residual matter from the deferrisation and demanganising of groundwater in Northern Germany. Residual matter of this type from other waterworks can also contain considerable parts of Al2O3 • H2O, Ca3(PO4)2 /Fe(PO)4 , Mg(OH)2 or acidic insoluble matter.

3) Example of a Fe flocculation sludge from the processing of catchment basin water. Fe flocculation sludge from other waterworks can also contain a significant share of CaCO3, CaSO4, Ca3(PO4)2/Fe(PO)4, MnO2 or Mg(OH)2.

4) Example of a Al flocculation sludge from the processing of catchment basin water. Al flocculation sludge from other waterworks can also contain a significant share of Ca3(PO4)2/Fe(PO)4, MnO2, or Mg(OH)2 as well as, under certain circumstances, a share of powdered active carbon.

5) Example of a sludge from the flocculation and sand washings from slow sand filtration from the processing of river water. 6) Corresponds with the double TOC value.

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5 Possible Effects with Feeding and introduction With the introduction or feeding of waterworks residual matter into wastewater systems, there are diverse interactions which, with the appropriate combination of wastewater and residual matter, type of wastewater discharge and treatment and with deliberate dosing, can lead to useful effects.

Residual matter containing iron for the bonding of hydrogen sulphide in digesters [14,15] and drains as well as for phosphate adsorption (Notes for the use of these residues can be found in Chap. 6) have the broadest application spectrum in wastewater systems. Residual matter containing aluminium can also be employed for phosphate adsorption. Residues containing lime can support conditioning with sludge dewatering.

The influences on the operation of wastewater facilities listed below are feasible, whereby the respective constraints decide which effect occurs in the individual case.

The effects can occur singly or together with very different influences in the individual case.

Possible effects in the sewer:

• H2S bonding in anaerobic areas

• fixing of phosphorus and also of BOD/COD

• deposits with low flow rates, in particular with residual matter from softening and decarbonisation.

Possible effects in the preliminary treatment stage:

• improved retention of filterable materials

• reduction of phosphorus and thus, as result, saving of flocculant with less salting of lakes and rivers

• raising of the primary sludge yield which, if required, can be compensated in part by the saving of flocculant

• reduction of BOD/COD

Possible effects in the biological stage:

• improvement of the nitrification, reduction of the denitrification performance and saving of oxygen with the employment of residual matter in the primary settling stage

• elimination of phosphorus and thus, as result, saving of flocculant with lower salting of lakes and rivers

• improvement of the settling characteristics with higher sludge indices

• lowering of the sludge age by increased surplus sludge removal (dependent on the change of index) with dosing in the active sludge stage

• reduction of AOX and humic matter in the effluent of wastewater treatment plants with residual matter containing active carbon

• Increase of the acidic buffer capacity.

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Possible effects on sludge digestion:

• reduction of the retention time in the digester and increase of heat requirement as a result of greater sludge yield

• phosphorus fixing

• improvement of the gas quality through H2S bonding and, parallel to this, increase of the CH4 element.

Possible effects on sludge dewatering and disposal:

• greater sludge yield corresponding to the waterworks sludge input (1 to 5 % of the DR (dry residue) load with identical catchment areas for water supply and wastewater disposal), which is, in part, reduced through precipitant composition and digestion.

• change of thickening and dewatering characteristics

• reduction of the thermal value

• reduction of the phosphorus reversal with dosing of iron sludge, in particular with plants with increased biological phosphorus elimination

• change of the sewage sludge composition depending on the input of waterworks residual matter

• with active carbon residues: increase of the thermal value and the pollutant load (for example AOX)

The effects listed, with the introduction or feeding of waterworks residual matter into the effected process stage, can occur singly or in combination. As a rule, the effects can be estimated based on analyses and available experience. If this should not be possible, trial operation with, if required, supplementary tests are recommended first.

Should the introduction or feeding of waterworks residual matter influence the operation of the wastewater facility negatively, there are, to a certain extent, possibilities of reducing or stopping these effects by appropriate measures on the part of the water supplier.

Such measures could be:

• pre-treatment (for example to remove coarse materials or for the separation of sand from the waterworks residual matter)

• separation of different sorts of residue with the aim of separate disposal (for example, of residual matter containing lime and iron)

• storage of residual matter either to even out the hydraulic loading or with the aim of dosing to fit the requirement.

6 Notes for the Use of Residual Matter Containing Iron Above all, waterworks residues containing iron offer diverse possibilities for utilisation in wastewater systems due to the bonding capacity for phosphorus and sulphide. The normal input settings and the therewith associated utilisation aspects are shown in Fig. 1.

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Fig. 1: Input and usage of iron hydroxide sludge in wastewater facilities

Through the controlled employment of iron sludge it is possible to counter problems in sewers (odour, corrosion) caused by sulphides [11]. An advantage is the addition of an iron sludge to the wastewater already containing sulphide. With the dosing of 2 to 3 g of iron per g sulphide, the conversion of sulphide, dependent on the reaction time and the sulphide content, is almost complete. The reaction rate is influenced by the wastewater matrix. As a side effect, dissolved phosphates are bonded and the acid buffer capacity of the wastewater increased. Depositing due to waterworks residual matter in sewers and siphons are to be avoided if the solid matter content of the sludge lies below 3 % or, with higher contents, the sludge is intensively mixed, evenly dosed and not added in surges.

The dosing of iron sludge for phosphate elimination is possible in the sewer network, in the wastewater treatment installations and in the facilities for sludge treatment. With this, in the aerobic milieu, a phosphate adsorption takes place which, in its effect, is heavily dependent on the pre-loading with organic compounds, the pH value and the calcium content [6]. With the same dosing the phosphate elimination is, however, significantly smaller than with the employment of commercial precipitant (ca. 10 to 20 %). To be rated as a positive side effect is the concurrent retention of COD and filterable substances. Better effects with regard to phosphorus elimination are achieved, if the iron (III) hydroxide in the anaerobic milieu is reduced, for example through sulphide. Thus bivalent iron is available for precipitation which, for example with wastewater treatment plants with increased biological P-elimination, leads to a significantly smaller reversal effects from digesters and thickeners.

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The employment of iron salts for sulphide bonding in digesters is operational practice in many wastewater treatment plants. Iron sludge can be dosed with comparable effectiveness as, in both cases, the same chemical reactions lead to sulphide precipitation. [7]. With ß values of 2.2. to 2.5, referred to the sulphide sum in the sludge and in the gas, normally one finds H2S contents in digester gas of below 100 ppm. With this there is no need for gas cleaning. As side effect a precipitation of redissolved phosphate occurs. The effects described can also be achieved in plants for anaerobic wastewater treatment.

In wastewater plants the waterworks residual matter is always to be found again, independent of the input point, in the sludge treatment and disposal stage. With the identical connection capacity for water supply and wastewater treatment the portion of the load of the waterworks sludge is normally between 1 and 5 % of the total dry residual matter. With the calculation of the increase of sewage sludge through waterworks sludge the digestible parts and chemical conversion of sludge content substances must be taken into account. The dewatering behaviour of a waterworks sludge is very dependent on the type of sludge. Investigations into iron sludge have shown that the filter cake mass of a mechanically dewatered mixed sludge with up to 10 % iron sludge component, is only slightly increased. With higher inputs the filter cake mass of the mixed sludge was less than the sum of the separately dewatered sludges [9].

7 Prerequisites and Technical Possibilities 7.1 General Prerequisites

The possible effects of waterworks residual matter on the operation of wastewater systems are to be checked by the system operators. The residual matter, due to its properties may not prejudice the operation of the wastewater and sludge treatment Overdosing is, in particular, to be avoided.

The agreement of the wastewater system operators and, if required, that of the responsible authority is necessary. A suitable dosing point for the waterworks residual matter as well as the quantity and period of dosing are to be agreed with all those involved.

For this the following information is required for analysis by the wastewater system operator:

• source of the water containing sludge or the sludge itself

• volume and mass flows or solid matter load

• chronological yield of the water containing sludge or the sludge itself which has to be discharged

• portion and range of variation of the main content substances

• content of environmentally relevant substances

• share of nutrients (nitrogen, phosphorus, potassium).

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7.2 Discharge into the Sewer System

For discharge into the sewer system and all its installations the following prerequisites must be fulfilled:

• sufficiently dimensioned sewer system

• prevention of long-term deposits

• sufficiently dimensioned wastewater treatment facilities including sludge treatment facility

If the residual matter from water supply systems is discharged as wastewater, ATV Standard ATV A-115 [1] is to be observed. Here, it can be practical for the wastewater system operator to allow the guidance values given in ATV Standard ATV-A 115, Annex 1 (ATV-A 115, Sect. 4.4) to be exceeded if, through this, the health of those working in the wastewater plant is not endangered, the structure and the operation of the plant are not prejudiced, the observation of conditions under water law, including sludge treatment and disposal are not made more difficult and that one does not have to reckon with damaging environmental influences (for example odour nuisances (ATV A-115, Sect. 4.1).

With combined sewer systems attention is to be paid to the position of the stormwater overflow.

If elevators or pumping stations are present in the sewer network, then the following prerequisites are to be checked for discharge:

• pumping station/elevators must be sufficiently dimensioned

• installation for the control of pumps (water level measurements) may not be impaired.

7.3 Feeding and/or Introduction into Wastewater Treatment Facilities

If feeding cannot be carried out due to unfavourable hydraulic conditions in the sewer network or due to a lack of possibilities for connection, there is a chance of direct feed via a transport pipeline or using vehicles. If a deliberate dosing into certain process stages in the wastewater treatment facilities is desired for technical operational reasons, these transport paths are equally necessary. With the latter possibility a previous thickening of the water containing the sludge can be practical for reasons of cost.

Residual matter can be fed in before the following process stages (see also Fig. 1):

• grit chamber or primary clarification

• aeration

• sludge thickening

• digestion

• sludge dewatering

• sludge drying/sludge incineration

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Feeding before the secondary settling tanks and before a possible additional existing filtration stage is not sensible.

Prerequisites for feeding/introduction are:

• sufficiently dimensioned wastewater treatment facilities including sludge treatment

• prevention of overloading of process stages

• prevention of defects in the measurement, control and regulation facilities

• avoidance of negative influences on the sewage sludge quality.

8 Notes on Economy The disposal of waterworks residual matter, depending on the disposal path, gives rise to different costs. Their amount is an essential criterion for the operator for the selection of the disposal path.

For the determination of the costs, first the technical prerequisites for the feeding-in of waterworks residues is to be clarified with the operator of the accepting wastewater plant.

Thereafter the following cost components can be determined:

• additional treatment of waterworks residue before discharge (for example removal of coarse material)

• transportation to the discharge or transfer point

• monitoring of the sludge quality

• cost of servicing loans, cost share for operation and maintenance of additional facilities such as, for example, storage and dosing facilities.

These costs are to be calculated into the treatment and disposal costs in the wastewater facility (here attention is to be paid to the digestible part and the thermal value changes with incineration).

With the determination of these costs the operator of the wastewater facility should take into account the following factors:

• saving of operational material (for example for P and H2S elimination (precipitant and for combatting odours (oxygen))

• increased energy yield and lower gas motor maintenance by improvement of digester gas quality

• costs for alternative facilities, for example for combatting odours in the sewer network, which are compensated by the introduction of sludge.

9 Checklists Below are the checklists, which provide the necessary details and constraints for a possible feeding or introduction of waterworks residual matter into wastewater facilities.

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Checklist 9.1 refers to the quantity and composition of the waterworks residues concerned, the most varied constraints which should be known before the feeding or introduction of waterworks residual matter and additional general details on those involved. Checklist 9.1 is to be filled in by the waterworks operator and serves as information basis for the wastewater facility operator(s). Details are based on ATV Standard ATV-A 115 "Discharge of Non-domestic Wastewater into a Public Wastewater System" [1] as well as the questionnaire in ATV Standard ATV-A 163, Part 1, "Indirect Dischargers/Registration" [2] and adjusted for the special case of feeding/introduction of waterworks residual matter into wastewater facilities.

Checklist 9.2 shows which areas and/or characteristic values of wastewater treatment facilities have to be taken into consideration. They serve as working document for discussions between waterworks and wastewater facility operators.

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9.1 Details on the Waterworks

Operator data Unit

Name/firm's name of the waterworks

Address

Focal point

Telephone Fax

Source of processed water (for example groundwater, surface water)

Area supplied with drinking water

Quantity of drinking water produced m3/a

Type and method of processing

Input materials/operating materials kg/a

Type and source of the waterworks residual matter, waste code number i.a.w. EWCO, for example

Residual matter from flocculation using Al compounds

Residual matter from flocculation using iron compounds

Residual matter from deferrisation and demanganising (comp. Chap. 3)

EWCO waste code

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Details on the waterworks residual matter (give following parameters dependent on the type of sludge concerned)

Type of sludge: (for example residue from flocculation using iron compounds)

Yield of substances by time (continuous/with discontinuous yield give unit of time)

Are there possibilities for intermediate storage available?

kg/a or kg/time

kg/time or m3/time

Water content and solid matter content or share of settlable matter

% or ml/l after 0.5 h

pH value

Organic matter (note: organic matter = 2 x TOC) comp. Chap. 4, Table 1)

% DR

Active carbon % DR

Content substances/analyses of waterworks residual matter (at least the parameters of the AbfKlärV and other environmentally relevant substances, for example As, in addition their variation range and previous curves, as far as available) (comp. Chap. 4)

Is there a preliminary treatment of the sludge or is a preliminary treatment planned?

Previous disposal routes of the sludge or the water containing the sludge

Are changes to the sludge concerned possible by modifying the production process, the employment of operational material etc.? (comp. Chap. 5)

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Details on the discharge/on the transport of the residual matter from the waterworks

Wastewater types which are treated in a wastewater treatment facility:

Wastewater from the drainage of properties in the combined system

Flushing water and wastewater from the processing of drinking water

m3/a

m3/a

Transfer point in the sewerage system N°./description

Wastewater examinations:

• Discontinuous examinations:

− Own investigations

− Outside investigations

• Continuous examinations:

− Registration continuous?

− Registration discontinuous?

N°. per year

N°. per year

Yes/no

Yes/no, Chronological separation

Facilities for retention of contaminated water (fire, accident defect) available ?

Yes/no if yes, type

Operational peculiarities:

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9.2 Checklists for the Wastewater Facilities Operator(s)

9.2.1 Sewers, Pumping Stations, Elevators

Operator data

Name/Firm's name

Address

Focal point

Telephone

Fax

Sewer

Is the sewer system sufficiently dimensioned? yes/no

Is there sufficient gradient available to prevent deposits?

yes/no

Is a sufficient rate of flow available to prevent deposits, in particular with heavily thickened sludge and with residual matter from water softening and decarbonisation?

yes/no

Is the position of the stormwater overflow in the combined system taken into account after the introduction point?

yes/no

Does the sewer network operator give his agreement to the usage?

yes/no

Pumping station/elevator

Are the existing pumps and elevator facilities sufficiently dimensioned?

yes/no

Is an impairment of the facilities for control of the pumps (for example the water level measurement) excluded?

yes/no

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9.2.2 Wastewater Treatment Facility

Operator data Unit

Name of the wastewater treatment facility

Address

Focal point

Telephone

Fax

Number of connected inhabitants (I) and population equivalents (PE) (loading as annual average in E + PE)

PT

Expansion capacity of the wastewater treatment facility (dimensioning capacity according to notice of approval in PT

PT

Annual amount of wastewater treated in total: • domestic and small commercial • commercial and industrial • infiltration water

m3/a m3/a m3/a m3/a

Sufficient dimensioning of the wastewater treatment facility for the desired joint treatment of waterworks residual matter available?

yes/no

Discharge via the sewer ensured?or suitable dosing and storage facilities for introduction into the wastewater treatment facility available?

yes/no yes/no

Is an operational test run possible? yes/no

Approval of responsible authority? yes/no

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Description of the wastewater treatment facility (possible discharge or dosing points with delivery per tanker vehicle)

Available Suitable dosing possible?

Remarks

• Grit chamber • Primary clarification • Aeration • Sludge thickening • Digestion • Sludge dewatering • Sludge drying/incineration

yes/no yes/no yes/no yes/no yes/no yes/no yes/no

Sewage sludge

yes/no Quantity in mD in t/a Effects on the disposal path:

• Agricultural utilisation i.a.w. AbfKlärV

• Other farming utilisation • Composting • Incineration • Landfill • Transfer to another wastewater

treatment facility • Others (please describe)

yes/no yes/no yes/no yes/no yes/no yes/no yes/no

Change of thermal value through increase of the share of inert material in the sewage sludge or through the share of active carbon?

Modification of the thickening and dewatering characteristics? Determined through experience values or test runs)

Change of sewage sludge composition?

Is the sludge treatment facility sufficiently dimensioned for a joint treatment of additional waterworks residual matter?

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10 Summary Assessment Residual matter, which has to be disposed of, is produced with water processing. A possibility for disposal is provided by the feeding or introduction into wastewater facilities. As soon as these residues are fed or introduced into the wastewater facility under regulations according to water law, they are disposed of as wastewater.

The residual matter can also be introduced as waste for utilisation in wastewater facilities.

The disposal of the residual matter requires, in every case of application, an individual case examination according to technical, legal and economic aspects. Depending on the source of the residual matter it can provide advantages for operational management which cannot, in every case, be valued in terms of money. Furthermore, the existing infrastructure of a wastewater facility can be used for disposal.

In the past the effect of waterworks residual matter, in particular iron sludge, has been verified in several investigations with the deliberate discharge or introduction into wastewater facilities. To be stressed are the reduction of the sulphide contents in the wastewater and/or sewage sludge and the thus associated improvements in the sewer network and the biogas quality. Further, the adsorption capacity and the positive effect with precipitation of wastewater and sewage sludge treatment can be applied to advantage.

The amounts of waterworks residual matter, with the same supply and disposal area, are small in comparison with the flows of wastewater and the yield of sewage sludge. With this background, in the normal case, only slight effects on the disposal of wastewater are to be expected which can be verified in the individual application case.

Residual matter from water processing can therefore be fed or introduced into wastewater facilities if this is technically and legally possible and is also economically justifiable. Otherwise it is to be disposed of as waste.

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11 Literature [Translator's note: known translations are given as normal text. Otherwise a courtesy translation of the title of the publication is given in square brackets]

[1] ATV Standards Wastewater - Waste, ATV Standard ATV-A 115E Discharge of Non-Domestic Wastewater into a Public Wastewater System October 1994,

[2] ATV Standards Wastewater - Waste, ATV Standard ATV-A 163E, Part 1 Indirect Dischargers, Part 1 Registration November 1992

[3] DVGW Standard W 221 Rückstände und Nebenprodukte aus Wasseraufbereitungsanlagen [Residual matter and by-products from water processing facilities] Teil 1: Grundsätze und Planungsgrundlagen [Part 1: Principles and fundamentals of planning] Teil 2: Behandlung [Part 2: Treatment Teil 3: Vermeidung, Verwertung und Beseitigung [Part 3: l Prevention, utilisation and disposal] Printing 1999

[3a] DVGW Standard W 222 Einleiten und Einbringen von Rückständen aus Anlagen der Wasserversorgung in Abwasseranlagen [Feeding and introduction of residual matter from water supply facilities into wastewater facilities] Printing 1999

[4] F. Sarfelt Schlammverwertung - Erfahrungen der Berliner Wasserbetriebe; in: "Entsorgung von Wasserwerksschlämmen" [Sludge utilisation - experience of the Berlin water services in: "Disposal of waterworks sludge"] DVGW-Schriftenreihe Wasser No. 68, 1991

[5] E. Zimmermann Schlammverwertung - Erfahrungen der Stadtwässerung Wiesbaden; in: "Entsorgung von Wasserwerksschlämmen" [Sludge utilisation - experience of the Wiesbaden water services in: "Disposal of waterworks sludge"] DVGW-Schriftenreihe Wasser No. 68, 1991

[6] S. Thole, S. Martin, M. Jekel Verwertung von eisenhaltigen Wasserwerksschlämmen zur Phosphatelimination [Utilisation of waterworks sludge containing iron for phosphate elimination] Korrespondenz Abwasser, 41 (1994), No. 11, p. 2024 - 2028

[7] S. Benzinger, E. Dammann Einsatz von Eisenhydroxidschlamm aus der Grundwasseraufbereitung zur Schwefelwasserstoffbekämpfung in der Abwasserbehandlung [Employment of iron hydroxide sludge from the processing of groundwater for combatting hydrogen sulphide in wastewater treatment gwf Wasser/Abwasser, 136 (1995), Vol. 5

[8] N. Schürmann, V. Mayer, R. Hamacher Praxisversuche zur gemeinsamen Entwässerung von Schlämmen aus Wasseraufbereitungsanlagen und einer kommunalen Abwasserbehandlungsanlage in Kammerfilterpressen [Practical trials on the joint dewatering in chamber filter presses of sludges from wastewater treatment facilities] gwf Wasser/Abwasser, 131 (1990), N°. 9, p. 472-480

[9] E. Dammann, W. Such, K. Wichmann Kapitel 12: Wasserwerksrückstände; in: Abwassertechnische Vereinigung e. V (Herausgeber): Handbuch Klärschlamm [Chap. 12: Waterworks residues in: German Association for Wastewater, Waste and Water Management (publisher): Sewage Sludge handbook, 4th Edition 1996, p. 583-612 Ernst & Sohn Verlag für Architekten und technische Wissenschaften GmbH, Berlin

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[10] S. Benzinger, E. Dammann, K. Wichmann Nutzung von Eisenhydroxidschlamm aus der Grundwasseraufbereitung von kommunalen Abwasseranlagen [Use of iron hydroxide sludge from the processing of groundwater by municipal sewage treatment plants] Korrespondenz Abwasser, 43 (1996), No. 9, p. 1552-1560

[11] R. Knutzen, S. Benzinger, E. Dammann Beseitigung von Sulfidproblemen in Abwasserkanälen durch Eisenhydroxidschlamm [Removal of the sulphide problem in sewers using iron hydroxide sludge] Entsorgungspraxis Vol. 5. 1997

[12] S. Schneider Rückstände aus der Trinkwasseraufbereitung in Deutschland: Mengen, Zusammensetzung und Entsorgungswege [Residual matter from the processing of drinking water in Germany: quantities, composition and disposal routes] Final report, ESWE-Institut, Wiesbaden, September 1996

[13] EWC-Ordinance (EWCO) Ordinance on the introduction of the European Waste Catalogue dated 13 September 1996 (Notified in Germany in BGBl. I, p. 1428)

[14] ATV-Arbeitsbericht [ATV Report] Gewinnung, Aufbereitung und Verwertung von Biogas [Production, processing and utilisation of biogas] Korrespondenz Abwasser, 41 (1994), No. 8

[15] ATV Standards Wastewater - Waste, ATV Advisory Leaflet ATV-M 363 Herkunft, Aufbereitung und Verwertung von Biogas [Source processing and utilisation of biogas] Geplante Fertigstellung 2000, GFA, D-53773 Hennef

[16] ATV-Arbeitsbericht der ad hoc-Arbeitsgruppe "Rechtliche Abgrenzungsfragen Abwasser/Abfall" mit Teilnahme des DVGW Entsorgung von Wasserwerksrückständen in kommunalen Abwasseranlagen - wasserrechtliche und abfallrechtliche Zulässigkeitsvoraussetzungen [ATV Report by the ad hoc Working Group "Legal delimitation questions on wastewater/waste" with the participation of DVGW Disposal of waterworks residues in municipal wastewater facilities - prerequisites for authorisation under water and waste law] Korrespondenz Abwasser No. 9. (1998), p. 1717-1722

[17] P. Nisipeanu, E. Dammann, W. Such Rechtliche Aspekte der Entsorgung von Wasserwerksrückständen in kommunalen Abwasseranlagen [Legal aspects of the disposal of waterworks residues in municipal wastewater facilities] gwf Wasser/Abwasser, No. 10 (1998), p. 646-649

[18] ATV-Regelwerk Abwasser - Abfall, Arbeitsblatt ATV-A 202 Verfahren zur Elimination von Phosphor aus Abwasser [ATV Standards Wastewater - Waste, ATV Standard ATV-A 202 Procedures for the Elimination of Phosphorus from Wastewater] October 1992, GFA, D-53773 Hennef