Reference number
DRS 353-5: 2018
© RSB 2018
 
 
 RWANDA 
STANDARD  DRS 
353-5 
 
First edition  
2018-mm-dd  
 
Water quality — Chemicals used for 
treatment of water intended for human 
consumption — 
Part 5: 
Bentonite 
  DRS 353-5: 2018 
©RSB 2018 - 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 
 
 
 
 
 
 
 
 
© RSB 2018 
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 RSB. 
Requests for permission to reproduce this document should be addressed to: 
Rwanda Standards Board 
P.O Box 7099 Kigali-Rwanda 
KK 15 Rd, 49 
Tel. +250 788303492 
Toll Free: 3250 
E-mail: info@rsb.gov.rw 
Website: www.rsb.gov.rw  
ePortal: www.portal.rsb.gov.rw  DRS 353-5: 2018 
iii                ©RSB 2018 - All rights reserved 
 Contents Page 
1 Scope ...................................................................................................................................................... 1  
2 Normative references ............................................................................................................................ 1  
3 Terms, definitions and symbols .......................................................................................................... 1  
4 Description ............................................................................................................................................. 1  
4.1 Identification .......................................................................................................................................... 1  
4.2 Commercial form ................................................................................................................................... 2  
5 Physical properties ............................................................................................................................... 2  
5.1 Appearance ............................................................................................................................................ 2  
5.2 Particle size distribution ....................................................................................................................... 2  
5.3 Bulk density packed .............................................................................................................................. 2  
6 Chemical properties .............................................................................................................................. 2  
6.1 General ................................................................................................................................................... 2  
6.2 Impurities and main by-products ......................................................................................................... 3  
7 Labelling – Transportation – Storage –order needs to be reconsidered ......................................... 3  
7.1 Transportation ....................................................................................................................................... 3  
7.2 Labelling ................................................................................................................................................. 3  
7.3 Storage ................................................................................................................................................... 4  
Annex A (informative)  General information on bentonite ............................................................................. 5  
A.1 Origin ...................................................................................................................................................... 5  
A.2 Physical properties ............................................................................................................................... 5  
A.3 Use .......................................................................................................................................................... 5  
A.4 Rules for safe handling and use .......................................................................................................... 5  
A.5 Emergency procedure........................................................................................................................... 5  
 DRS 353-5: 2018 
©RSB 2018 - All rights reserved                  iv 
 Foreword  
Rwanda Standards are prepared by Technical Committees and approved by Rwanda 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 Standards 
adopted by Technical committees are ratified by members of RSB Board of Directors for publication and 
gazettment as Rwanda Standards. 
DRS 353-5 was prepared by Technical Committee RSB/TC 013, Water and Sanitation ,  
In the preparation of this standard, reference was made to the following standard: 
BS EN 16370:2013: Chemicals used for treatment of water intended for human consumption —Sodium 
chloride for onsite electrochlorination using membrane cells 
The assistance derived from the above source is hereby acknowledged with thanks. 
DRS 353 consists of the following parts, under the general title Water quality — Chemicals used for treatment 
of water intended for human consumption : 
 Part 1: Aluminium sulfate  
 Part 2: Calcium hypochlorite  
 Part 3: Sodium chlorate  
Part 4: Sodium chloride 
Part 5: Bentonite 
  DRS 353-5: 2018 
v                ©RSB 2018 - All rights reserved 
 Committee membership  
The following organizations were represented on the Technical Committee on Water and Sanitation (RSB/TC 
013) in the preparation of this standard. 
Ministry of Environment (MoE) 
Ministry of Disaster Management and Refugee Affairs (MIDIMAR) 
Ruliba Clays Limited 
Shine Engineers Multisectoral Company Limited (SEMC Ltd)   
Sulfo Rwanda Industries (SULFO) 
University of Rwanda/College of Science and Technology (UR/CST) 
Water and Sanitation Corporation Ltd (WASAC Ltd) 
Rwanda Standards Board (RSB) – Secretariat DRS 353-5: 2018 
©RSB 2018 - All rights reserved                  vi 
 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 and RS EAS 12 
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 353-5: 2018 
1                ©RSB 2018 - All rights reserved 
 Water quality — Chemicals used for treatment of water intended 
for human consumption — Part 4: Bentonite 
1 Scope  
This Preliminary Draft Standard describes the characteristics and specifies the requirements and the 
corresponding test methods for bentonite. 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 21587-2:2007 Chemical analysis of aluminosilicate refractory products (alternative to the X-ray 
fluorescence method) -- Part 2: Wet chemical analysis  
ISO 21587-3:2007 Chemical analysis of aluminosilicate refractory products (alternative to the X-ray 
fluorescence method) -- Part 3: Inductively coupled plasma and atomic absorption spectrometry methods  
ISO 11465, Soil quality — Determination of dry matter and water content on a mass basis — Gravimetric 
method 
ASTM D422, Standard Test Method for Particle-Size Analysis of Soils 
3 Terms, definitions and symbols 
No terms and definitions are listed in this document. 
4 Description 
4.1 Identification  
4.1.1 Synonym or common names 
Montmorillonite, Bentonite, Amargosite, Ardmorite, Askanite, Confolensite, Erinite, Galapectite, Malthacite, 
Samoïte, Steargilite, Stolpenite, Wilkonite.  
Montmorillonite and bentonite are the most commonly used names. 
4.1.2 Chemical formula 
𝑆𝑖ସ𝐴𝑙ଶି௫ 𝑀(𝐼𝐼)௫𝑀(𝐼)௫ା𝑂ଵ଴(𝑂𝐻)ଶ.𝑛𝐻ଶ𝑂      , where x varies from 0 to 2. DRS 353-5: 2018 
©RSB 2018 - All rights reserved                  2 
 The divalent metal M(II) can be replaced completely or partly by monovalent metal M(I) so as to maintain 
electrical charge equilibrium. 
4.2 Commercial form 
The product is available in powder form in many grades differing in purity and monovalent ion (Na+) 
concentration. 
5 Physical properties 
5.1 Appearance 
The product is a white to light brown or green powder. 
5.2 Particle size distribution 
5.2.1 At least a mass fraction of 95 % of the product shall have a particle size less than 500 μm.  
5.2.2 The particle size distribution shall be determined in accordance with ASTM D422. 
NOTE The particle size distribution is commonly specified as a given mass fraction less than a given particle size.  
5.2.3 The particle size distribution shall be within the manufacturer’s declared values. 
5.3 Bulk density packed 
The bulk density packed shall be in the range 800 kg/m3 to 1 000 kg/m3. 
6 Chemical properties 
6.1 General 
This Standard specifies the minimum purity requirements for bentonite 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 necessary, to relevant authorities. 
NOTE Users of the product should 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 standard, and 
other relevant factors. 
 DRS 353-5: 2018 
3                ©RSB 2018 - All rights reserved 
 6.2 Impurities and main by-products 
The composition of the commercial product shall conform to Table 1 
Table 1 – limits for impurities and by-products commonly present in bentonite 
Limit as a mass fraction in % of the product Test Methods 
Parameter  Minimum  Maximum  
SiO2 50 70 
ISO 21587-  
ISO 21587-3 
 Al2O3 10 20 
MgO 1 4,5 
CaO 0,5 4 
Na2O 0,5 3 
Mass loss at 105 °C  0  15  ISO 11465 
 
7 Labelling – Transportation – Storage –order needs to be reconsidered 
7.1 Transportation 
7.1.1 Bentonite is not classified as dangerous for transportation by road, rail, sea or air. 
7.1.2 Bentonite shall be delivered in bags and bulk. 
7.1.3 In order that the purity of the product is not affected, the means of delivery shall not have been used 
previously for any different product or it shall have been specially cleaned and prepared before use. 
   
7.2 Labelling 
The marking shall include the following information: 
a) the name "bentonite", trade name and grade; 
b) net mass; 
c) density/concentration;  
d) name and the address of the supplier and/or manufacturer;  DRS 353-5: 2018 
©RSB 2018 - All rights reserved                  4 
 e) statement of conformity to the standard; 
f) Shelf life; 
g) Storage conditions; and 
h) Batch number.  
The supplier shall provide a certificate of analysis against the standards and the material Safety Data sheet 
NOTE the user should verify the relevance of that certificate 
7.3 Storage 
7.3.1 Long-term stability 
7.3.1.1 The product is stable but hygroscopic. 
The product can be stored for one or two years if kept dry and away from volatile materials which can adsorb 
on the bentonite. 
7.3.2 Storage incompatibilities 
Keep away from volatile solvents, odorous products and moisture. 
 DRS 353-5: 2018 
5                ©RSB 2018 - All rights reserved 
 Annex A 
(informative)  
 
General information on bentonite 
A.1 Origin 
A.1.1 Raw material 
Bentonite exists in nature as a clay deposit. It is generally contaminated by sand and rocks. 
A.1.2 Manufacturing process 
Bentonite is produced by mining and crushing in the quarry and then treating in a plant where it is crushed to 
the end use size and dried. By mixing powdered sodium carbonate during crushing it is possible to exchange 
the divalent metal (generally Ca2+) partly by Na+; this increases the swelling properties of the bentonite. 
A.2 Physical properties 
The absolute density is in the range 2 g/cm3 to 2,4 g/cm3. 
A.3 Use 
A.3.1 Function 
Bentonite is used to weigh down a flock when there is a low amount of suspended solids in the water. 
A.3.2 Treatment dose 
The treatment dose depends on raw water quality, process plant and treatment objectives and is generally up 
to 20 mg/l. 
A.4 Rules for safe handling and use 
Bentonite is not a hazardous product. It is recommended to avoid exposure to the dust which is irritating to the 
nose and throat. 
A.5 Emergency procedure 
A.5.1 First aid. 
In case of contact with skin, there is no danger - it is recommended to wash with soap and water. DRS 353-5: 2018 
©RSB 2018 - All rights reserved                  6 
 In case of contact with eyes, it is recommended to flush with plenty of water. 
In case of inhalation, it is recommended to move to fresh air 
A.5.2 A.5.2 Spillage 
It is recommended to sweep up and to discard in a refuse container. 
  DRS 353-5: 2018 
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 Bibliography 
[1] ISO 13500:2008 , Petroleum and natural gas industries — Drilling fluid materials — Specifications and 
tests 
 
 
 DRS 353-5: 2018 
ICS 71.100.80  
 
©RSB 2018 - All rights reserved