Drinking-Water Supply for CKDu Affected Areas of Sri Lanka, Using Nanofiltration Membrane Technology: From Laboratory to Practice

Titus Cooray,Libing Zheng,Sujithra K Weragoda,Junya Zhang,Rohan Weerasooriya,Yuansong Wei,Hui Zhong

doi:10.3390/w11122512

Abstract

Installation of decentralized water-treatment plants is an ideal option to supply safe drinking water for rural communities. Presently in Sri Lanka, over 3.6 million villagers face acute water-quality problems, and chronic kidney disease of unknown etiology (CKDu) is also prevalent among this community. Most of the drinking water in these villages is unpalatable due to high hardness and salinity. As an interim measure, reverse-osmosis (RO) water-treatment plants are introduced to provide safe water. However, due to deficient electrolytes, RO-treated water tastes unpleasant to some consumers; hence, people refuse it after prolonged use. The operation, maintenance, and management of RO plants are other major problems. Aimed at providing safe drinking water to the rural sector in a cost-effective manner, in this study, we fabricated an automated drinking-water purification system based on nanofiltration (NF) membrane technology, which can remove divalent cations, dissolved organic carbon (DOC) and pathogens efficiently, and monovalent ions partially, and thus keep electrolytes to some degree. Ten commercial NF membranes were tested in a laboratory, for solute and DOC removal efficiency and robustness. The DF-90 membrane showed the highest removal of DOC and hardness, and it was therefore selected, to design a pilot NF drinking-water treatment plant. The adhered DOC by the membrane can be cleaned by NaOH solution (pH = 12). The pilot NF drinking-water treatment plant has been in use since September 2018, and it shows excellent performance of removing DOC, TDS, hardness, fluoride, and pathogens in groundwater, and the permeate water of the NF plant has been well-accepted by the stakeholders of the society. The dominant genus of source water, and throughout the two processes (NF and RO), is Pseudomonas, and their difference is significant in the concentrates of the NF and RO processes.

Highlights

We examined the chemical quality of groundwater from different chronic kidney disease of unknown etiology (CKDu) affected zones [12,13] and developed an integrated water quality index (WQI) [13] to demarcate water with high TDS, dissolved organic carbon (DOC), and fluoride in CKDu areas that requires treatment [14]
Ten commercially available NF membranes were tested for the rejection efficiency of hardness and DOC by the membranes, and the DF-90 membrane was selected due to its highest removal of DOC and hardness, for the construction of a pilot drinking-water treatment plant
The NaOH can be effectively used to remove foulants formed on the DF-90 membrane

Summary

Introduction

Chronic Kidney Disease of Unknown Etiology (CKDu) in Sri Lanka. In Sri Lanka, chronic kidney disease of unknown etiology (CKDu) was discovered over three decades ago and is epidemic among the rural farming community in the North Central Province (NCP), causing a severe national burden [1,2,3]. The CKDu has no relationship to known causes common to chronic kidney diseases such as obesity, hypertension, diabetes, or other factors, like snake bites. Over thirty or so hypotheses are proposed to elucidate disease etiology without any conclusion. Most of these hypotheses are somehow related to drinking-water quality.

Methods

Results

Conclusion