Reference number  
DRS  353-1: 2017  
© RBS yyyy 
© RSB 2017  
 
 RWANDA 
STANDARD  DRS  
353-1 
 
First e dition  
2017 -mm-dd 
 
Water quality  — Chemicals used for 
treatment of water intended for human 
consumption  
Part 1: 
Aluminium sulfate  
  DRS  353-1: 2017  
©RSB 2017 All rights reserved                  ii 
 
 In order to match with technological development and to keep continuous progress in industries, 
Standards are subject to periodic review. Users shall ascertain that they are in possession of the latest 
edition  
 
 
 
 
 
 
 
 
 
 
© RSB2017  
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized 
in any form or by any means, electronic or mechanical, including photocopying and microfilm, without 
prior written permission from R SB. 
Requests for permission to reproduce this document should be addressed to  
Rwanda Standards  Board  
P.O Box 7099 Kigali -Rwanda  
Tel. +250 252 586103/ 582945  
Toll Free: 3250  
E-mail: info@rsb.gov.rw  
Website: www.rsb.gov.rw  DRS 353 -1: 2017  
iii                 ©RSB2017  All rights reserved  
 
 Contents  Page 
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative references  ................................ ................................ ................................ ............................  1 
3 Description  ................................ ................................ ................................ ................................ .............  1 
4 Purity criteri a ................................ ................................ ................................ ................................ .........  4 
5 Labelling - Transportation - Storage  ................................ ................................ ................................ ... 5 
Annex  A (normative)  General rules relating to safety  ................................ ................................ ...................  8 
Annex  B (informative)  General information on aluminium sulfate ................................ ...............................  9 
Annex  C (informative)  Recommend ed test methods  ................................ ................................ ...................  12 
 DRS  353-1: 2017  
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 Foreword  
Rwanda Standard s are prepared  by Technical Committees and approved by R wanda Standards Board (RSB) 
Board  of Directors in  accordance with the procedures of RSB, in compliance with Annex 3 of the WTO/TBT 
agreement on the preparation, adoption and application of standards.  
The main task of technical committees is to prepare national standards.  Final Draft Rwanda S tandards 
adop ted by Technical committ ees are ratified by me mbers of RSB Board of Director s for publication and 
gazettment as Rwanda Standards.  
DRS 353-1 was prepared by Technical Committee RSB/TC 013, Environment, Health and Safety . 
In the preparation of this standard,  reference was made to the following standard:  
BS EN 878,  Chemicals used for treatment of water intended for human consumption — Aluminium sulfate  
The assistance de rived from the above source is hereby acknowledged with thanks.  
DRS 353 consists of the foll owing parts, under the general title Water quality  — Chemicals used for treatment 
of water intended for human consumption : 
 Part 1: Aluminium sulfate  
 Part 2: Calcium hypochlori te 
Part 3: Sodium chlorate  
  DRS 353 -1: 2017  
v                 ©RSB2017  All rights reserved  
 
 Committee membership  
The following organizations were represented on the Technical Committee on Environment, Health and Safety  
(RSB/TC 013) in the preparation of this standard.  
Integrated Polytechnic Regional Centre – Kigali ( IPRC -Kigali)  
Inyange Industries Ltd  
National Indust rial Research and Development Agency (NIRDA)  
Rwanda Natural Resource Authority (RNRA)  
Star Construction & Consultancy (SCC)  
University of Kibungo (UNIK)  
Water and Sanitation Corporation (WASAC)  
Rwanda  Standards Board (RSB) – Secretariat  DRS  353-1: 2017  
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 Introduction  
Treatment of water intended for human consumption can be achieved by using various chemicals which might 
raise the risk of cancer or cause other health hazards by creating toxic by -products that need tighter control in 
order to avoid those risks and meets requirements of drinking water as stated in RS EAS 153 . 
Chemicals used during treatment of water have to be of good quality and meet standards requirement, in 
order to avoid any contamination of water by impurities of these chemicals and therefore ensure a  successful 
water treatment . 
 DRS 353-1: 2017  
1                 ©RSB2017  All rights reserved  
 
 Water quality — Chemicals used for treatment of water intended for 
human consumption  — Part 1: Aluminium sulfate  
1 Scope  
This Preliminary Rwanda Standard describes the characteristics , specifies the requirements and gives 
reference to the analytical methods  of aluminum sulfate . It gives information on its use in water treatment  and 
also determines the rules relating to safe handling and use of aluminium sulfate . 
This standard is applicable only to aluminium sulfate used for treatment of water intended for human 
consumption.  
2 Normative references  
The following referenced documents  are indispensable for the application of this document. For dated 
references, only the edition cited applies. For undated references, the latest edition of the referenced 
document (including any amendments) applies.  
ISO 3165, Sampling of chemical products  for industrial use — Safety in sampling  
ISO 6206, Chemical products for industrial use — Sampling — Vocabulary  
3 Description  
3.1 Identification  
3.1.1  Chemical  name  
Aluminium sulfate . 
3.1.2  Synonyms or common  names  
Aluminium sulfate, cake alum, alum.  
NOTE  In English  the generic term “alum” is imprecise and is deprecated and in German the term “Alaun” is 
misleading.  
3.1.3  Relative molecular  mass  
342,14 for 
 Al2(SO4)3 
3.1.4  Empirical  formula  
Al2(SO4)3  
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 3.1.5  Chemical  formula  
Al2(SO4)3·n H2O 
3.1.6  Commercial forms  
Aluminium  sulfate is available in solid hydrated forms, with different particle sizes (slabs, kibbled, ground, 
granulated) and as aqueous solutions.  
3.2 Physical properties  
3.2.1  Appearance  
The product is a white solid or colourless to yellow, clear liquid  
3.2.2  Density  
The densit y of a typical aluminium sulfate solution is given in Table 1 and varies depending on the 
concentration of the active matter (aluminium content), expressed in grams per kilogram of solution (Al g/kg).  
Table 1 — Density of solution  
Al g/kg of solution  Densi ty (g/ml)  at 15 °C  
40,8 1,310  
41,6 1,315  
42,5 1,320  
43,3 1,325  
44,2 1,330  
45,0 1,335  
 
3.2.3  Solubility  
3.2.3.1  The theoretical limit of active matter content for a typical solution is given in Table 2  
Table 2 — Solubility  
Temperature  Active matter in  
°C  Al g/kg of solution  
24  44,8  
3.2.3.2  The practical limit of solubility depends on the temperature and the device used for solubilisation 
of the solid form (slabs, kibbled, ground or granulated).  
3.2.3.3  An indication of practi cal limits is given in  Table 3.  DRS 353-1: 2017  
3                 ©RSB2017  All rights reserved  
 
 Table 3 — Indication of practical limits of solubility  
Temperature  
°C  Active matter Al g/kg of solution  Solubility in grams solid form  
(containing Al 90 g/kg of solid) per 
kilogram of solution  
15  37  410  
 
3.2.4  Crystallization point  
The crystallization point of aluminium sulfate varies, depending on the concentration of the active matter. For 
example:  
̶ - 7 °C for a typical solution of aluminium content of 42,4 g/kg of solution.  
̶ Solution stored at low temperatures (below 0°C) can spont aneously form a solid mass of crystal hydrate.  
3.2.5 Viscosity (dynamic)  
The viscosity of aluminium sulfate solution varies greatly, depending on the concentration of the active matter. 
For a typical solution of aluminium content of 42,4 g/kg of solution, the  viscosity is given in Table 4.  
Table 4 — Viscosity  
Temperature  
°C Viscosity mPa.s 
(millipascal second)  
0 40,0 
10 26,5 
20 18,6 
30 13,2 
40 8,8 
 
3.2.6  Chemical properties  
 
Aluminium sulfate is an acidic hydrated salt or solution. Very dilute solutions hydrolyse and form a precipitate 
of aluminium hydroxide.  
NOTE  Since aluminium compounds are amphoteric in nature, the solubility of aluminium depends on the pH value 
and it is  advised to use the product within an appropriate pH range   
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 4 Purity criteria  
4.1 General  
4.1.1  This Standard specifies the minimum purity requirements for aluminium sulfate used for the treatment 
of water intended for human consumption. Limits are given for impurities commonly present in the product. 
Depending on the raw material and the manufacturing process other impurities can be present and, if so, this 
shall be notified to the user and when nec essary to relevant authorities.  
4.1.2  Users of the product sh all check the national regulations in order to clarify whether it is allowed/not 
banned and is of appropriate purity for  treatment of water intended for human consumption, taking into 
account raw water quality, required dosage, contents of other impurities  and additives used in the product not 
stated in the product standa rd, and other relevant factors.  
4.2 Composition of commercial product  
The concentration of active matter (aluminium content) in the product expressed as grams per kilogram of 
product shall be w ithin ± 3 % of the manufacturer's declared values.  
NOTE  The concentration of water -soluble aluminium in commercial products varies. Typical values are given here 
below:  
Commercial form  Al g/kg of product  
Solid  72 to 91  
Solution  32 to 44  
 
4.3 Impurities and main by -products  
The product shall conform to the requirements specified in Table 5.  
Table 5 — Limits of impurities  
Grade  Impurity  Limit (g/kg) 
Iron free  Iron (Fe)  max.  1,60 
Low iron  Iron (Fe)   1,60 < Fe ≤ 115 
All grades  Insoluble matter  max.  23 
NOTE  The value quoted for iron is for both iron (II) and iron (III). Iron can be present as a 
component of the product and will usually be removed in the treatment process.  
 DRS 353-1: 2017  
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 4.4 Chemical parameters  
The product shall conform to the requirements specified in Table 6.  
Table 6 — Chemical parameters  
Parameter  
  Limit (mg/kg ) 
Type 1  Type 2  Type 3  
Arsenic (As)  max.  14  40  100  
Cadmium (Cd)  max.  3  50  100  
Chromium (Cr)  max.  30  700  1 000  
Mercury (Hg)  max.  4  10  20  
Nickel (Ni)  max.  20  700  1 000  
Lead (Pb)  max.  40  200  800  
Antimony (Sb)  max.  20  40  120  
Selenium (Se)  max.  20  40  120  
NOTE  Cyanide (CN-) is usually not relevant because of the acidity of the product. Pesticides and 
polycyclic aromatic hydrocarbons are not relevant since the raw materials used in the manufacturing 
process are free of them. For maximum impact of these products on trace metal content in drinking 
water see A.2.  
 
5 Labelling - Transportation - Storage  
5.1 Means of delivery  
6.1.1  Solids : the product shall be delivered in suitable packages, paper or plastics bags, or by aluminium or 
mild steel tippers, or by rubber -lined or plastics -lined bulk truck (20 t to 35 t depending on transpor t regulations 
if applicable ) 
6.1.2  Bulk liquids : the product shall be delivered in tankers of corrosion -resistant materials.  
Note  The manufacturer can provide advice on suitable materials.  
In order that the purity of the product is not affected, the mean s of delivery should not have been used 
previously for any different product or it should have been specially cleaned and prepared before use.  
   
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 5.2 Labelling  
Labelling showing hazard statement shall apply to aluminium sulphate  products  
The following label bu t not limited to should be used  
 
 
 
 
 
 
 
 
 
5.3 Marking  
The marking shall include the following information:  
̶ name: “aluminium sulfate” trade name and grade ;  
̶ net mass;  
̶ name and the address of the supplier and/or manufacturer ; and  
̶ statement of conformity to the standard ”. 
̶ Shelf life  
̶ Storage conditions  
̶ Batch number  
The supplier shall provide a certificate of analysis against the standards  
Note  the user should verify  the relevance of that certificate  Signal word:  
Danger  
Hazard statements:  
- Causes serious eye damage  
- May be corrosive to metals  
- Skin attack  
- Etc 
Disposal statement   
DRS 353-1: 2017  
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 5.4 Storage  
5.4.1  General  
Storage in a cool and dry place  
NOTE  The manufacturer can provide advice on suitable mat erials and storage temperatures.  
  
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 Annex  A 
(normative)  
 
General rules relating to safety  
A.1 Rules for safe handling and use  
The supplier shall provide current safety instructions.  
A.2 Emergency procedures  
A.2.1  First aid  
A.2.1.1  In case of contact with skin wash thoroughly with cold water and seek medical advice if irritation 
persists.  
A.2.1.2  In case of contact with eyes rinse thoroughly with cold water and seek medical advice.  
A.2.1.3  In case of inhalation remove to fresh air,  loosen clothing and seek medical advice.  
A.2.1.4  In case of ingestion seek medical advice immediately.  
NOTE  In general, it is advised to treat the product as a weak acid.  
A.2.2  Spillage  
A.2.2.1  Refer to 6.5.3 for incompatibilities.  
A.2.2.2  Put on protecti ve clothing. Collect and dispose of spillages carefully.  
A.2.2.3  Dilute small spillages of liquid with water and flush to sewer.  
A.2.2.4  Neutralize and dispose of large spillages of liquid.  
NOTE 1  Local regulations might apply to the disposal of this p roduct.  
NOTE 2  Suitable neutralizing chemicals are diluted sodium hydroxide or sodium carbonate.  
A.2.3  Fire  
The product is non -flammable. Any extinguishing media can be used. The product can liberate toxic and 
corrosive fumes of sulfur dioxide and trioxide u nder extreme conditions when boiled to dryness or heated 
above 600 °C.  DRS 353-1: 2017  
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 Annex  B 
(informative)  
 
General i nformation on aluminium sulfate  
B.1 Origin  
B.1.1  Raw materials  
The typical raw materials are:  
a) sulfuric acid; and  
b) aluminium or aluminium oxide compounds such as:  
1) trihydrate;  
2) bauxite or clays of suitable composition;  
3) pickle liquors, purified if necessary; and  
4) aluminium foundry residues, purified if necessary.  
B.1.2  Manufacturing process  
A.1.2.1  Aluminium sulfate is a synthetically manufactured product.  
A.1.2.2  The typical  manufacturing process is the reaction of a raw material containing aluminium or 
aluminium compounds with sulfuric acid.  
B.2 Quality of commercial product  
The three types of aluminium sulfate specified in Table 6 reflect the quality of commercially available p roducts. 
Figures B.1 to B.2 show the maximum concentrations of trace metals that would be added to the raw water by 
the addition of products corresponding to the purity levels specified in Table 6. Furthermore, the figures 
overstate the concentrations of m etals that would be present in the treated water since a substantial 
proportion of the trace metals will be incorporated in the sludge. Users of this product should select an 
appropriate grade and type to enable them to achieve treated water quality target s taking into account raw 
water characteristics, required dosage, process plant conditions and other relevant factors.  
  
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Figure B.2 — Maximum impact of aluminium sulfate, Type 2, on trace metal content of water  
Key 
1 maximum addition to water µg/l metal  
2 product dosage mg/l Al - Typical dose  
B.3 Use 
B.3.1  Function  
Aluminium sulfate is used as a coagulant.  
B.3.2  Form in which it is used  
For a liquid product, the concentration of the solution used, expressed as Al, is generally about 10 g/l to 55 g/l 
(typically 10 g/kg to 44 g/kg).  
NOTE   Very dilute solutions hydrolyse and form a precipitate.  
B.3.3  Treatment dose  
The treatment dose is generall y 1 mg/l or more, expressed as Al, depending on raw water quality.  
DRS 353-1: 2017  
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 B.3.4  Means of application  
Solutions are usually applied using a positive displacement metering pump. Sufficient turbulence should be 
provided at the point of addition to promote rapid dispersion . 
B.3.5  Secondary effects  
a) reduction of pH value;  
b) reduction of alkalinity;  and 
c) increase in sulfate concentration.  
B.3.6  Removal of excess product  
The coagulation process should be operated under conditions (e.g. pH) in which the aluminium ions in the 
system are precipi tated and reduced below the maximum allowable concentration.  
   
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 Annex  C 
(informative ) 
 
Recommended test methods  
C.1 Test methods  
C.1.1  Sampling  
C.1.1.1  Solid  
Observe the general recommendations of ISO 3165 and take into account ISO 6206.  
Prepare the laboratory sample(s) required by the relevant procedure described in ISO 8213.  
 
C.1.1.2  Liquid  
C.1.1.2.1  Sampling from drums and bottles  
C.1.1.2.1.1  General  
C.1.1.2.1.1.1  Mix the contents of each container to be sampled by shaking the container, by rolling it or by 
rocking it from side to side, taking care not to damage the container or spill any of the liquid.  
C.1.1.2.1.1.2  If the design of the container is such (for exam ple, a narrow -necked bottle) that it is 
impracticable to use a sampling implement, take a sample by pouring after the contents have been thoroughly 
mixed. Otherwise, proceed as described in C.1.1.2.1.1.3 .  
C.1.1.2.1.1.3  Examine the surface of the liquid. I f there are signs of surface contamination, take samples 
from the surface as described in C.1.1.2.1.2; otherwise, take samples as described in C.1.1.2.1.3.  
C.1.1.2.1.2  Surface sampling  
Take a sample using a suitable ladle. Lower the ladle into the liquid until the rim  is just below the surface, so 
that the surface layer runs into it. Withdraw the ladle just before it fills completely and allow any liquid adhering 
to the ladle to drain off. If necessary, repeat this operation so that, when the other selected containers have 
been sampled in a similar manner, the total volume of sample required for subsequent analysis is obtained.  
C.1.1.2.1.3  Bottom sampling  
C.1.1.2.1.3.1  Take a sample using an open sampling tube, or a bottom -valve sampling tube, suited to the 
size of container and th e viscosity of the liquid.  DRS 353-1: 2017  
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 C.1.1.2.1.3.2  When using an open sampling tube, close it at the top and then lower the bottom end to the 
bottom of the container. Open the tube and move it rapidly so that the bottom of the tube traverses the bottom 
of the conta iner before the tube is filled. Close the tube, withdraw it from the container and allow any liquid 
adhering to the outside of the tube to drain off.  
C.1.1.2.1.3.3  When using a bottom -valve sampling tube, close the valve before lowering the tube into the 
container and then proceed in a similar manner to that when using an open sampling tube.  
C.1.1.2.1.4  Sampling from tanks and tankers  
From each access point, take samples as follows:  
d) from the surface of the liquid, using a ladle as described in C.1.1.2.1.2; and  
e) from t he bottom of the tank or tanker, using a sampling tube as described in C.1.1.2.1.3 or using a 
specially designed bottom -sampling apparatus;  
From one or more positions, depending on the overall depth, between the bottom and the surface using a 
weighted sam pling can.  
   
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C.1.2  Analyses  
The methods to be used for analysis of aluminium -based coagulants and the principles of each method are 
listed in Table C.1.2  
Table C.1.2 — Methods of analysis  
Determination  Method  
Aluminium  EDTA complexometric method,  titration with EDTA  
Aluminium  Separation of iron, CDTA complexometric titration  
Iron Atomic absorption spectrometry (flame)  
Iron Potentiometric titration  
Sodium  Atomic absorption spectrometry (flame)  
Calcium  Atomic absorption spectrometry (flame)  
Chloride  Potentiometric titration  
Sulfate  Barium sulfategravimetry  
Silicate  Reduced molybdosilicate spectrophotometry  
Free acidity  Acidimetric titration  
Basicity  Acidimetric titration, oxalate method  
Basicity  Acidimetric titration, KF method  
Insoluble matter  Gravimetry  
Arsenic  Inductively coupled plasma optical emission spectrometry (ICP/OES) (hydride)  
Cadmium  Inductively coupled plasma optical emission spectrometry (ICP/OES)  
Chromium  Inductively coupled plasma optical emission spectrometry (ICP/OES)  
Mercury  Atomic absorption spectrometry (flameless)  
Nickel  Inductively coupled plasma optical emission spectrometry (ICP/OES)  
Lead  Inductively coupled plasma optical emission spectrometry (ICP/OES)  
Antimony  Inductively coupled plasma optical emission spe ctrometry (ICP/OES) (hydride)  
Selenium  Inductively coupled plasma optical emission spectrometry (ICP/OES) (hydride)  
 
C.1.3  Expression of results  
C.1.3.1  Aluminium content  
The aluminium content shall be expressed in grams of aluminium per kilogram of product (Al g/kg).  The 
following equation gives the aluminium content expressed as alumina (Al 2O3):  
𝐴𝑙2𝑂3=(𝐴𝑙)×102
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 C.1.3.2  Repeatability  
Laboratory shall calculate the repeatability of the method under their laboratory conditions according to the 
procedure defined  in ISO 5725 -2. 
   
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Bibliography  
[1] EN 1302, Chemicals used for treatment of water intended for human consumption - Aluminium -based 
coagulants - Analytical methods  
[2] ISO 8213, Chemical products for industrial use — Sampling techniques — Solid chemical products in 
the fo rm of particles varying from powders to coarse lumps  
  DRS 353-1: 2017  
ICS 71.100. 80 
 
 
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