Performance of integrated sequencing batch reactor (SBR) and reverse osmosis (RO) process for leachate treatment: effect of pH

Izabela Anna Tałałaj

doi:10.1007/s40201-022-00788-0

Abstract

PurposeIn this paper the performance and effectiveness of the reverse osmosis (RO) process for the biologically pretreated leachate was investigated. The RO process was carried out separately for two different pH: 8.0 and 9.3.MethodsA general pollution parameters as well as organic and inorganic indicators were determined in raw, biologically pretreated and RO treated leachate. The performance characteristics of the reverse osmosis system were made on the basis of permeate flux, electroconductivity removal rate, concentration factor and efficiency in removal of analyzed parameters.ResultsThe use of SBR pretreatment had very good efficiency in BOD (97.3%) and ammonia nitrogen (95.4%) removal. The lowest effectivity was observed for chloride (11.6%), boron (3.9%) and TDS (1.2%). Pretreated leachate was subjected to RO system. The normalized average flux was 0.53 (42.3 L/m2·h) for pH = 8.0 and 0.68 (33.5 L/m2·h) for pH = 9.3. The lower membrane fouling at higher pH can be explained by electrostatic repulsion between the negatively charged membrane surface and organic substances. Independently of the process pH, a two-step membrane fouling was observed. The greatest differences in removal rates were observed for boron, which had a higher retention rate at higher pH, and ammonia nitrogen, whose removal rate decreased at higher pH. The obtained permeate pH after RO process was lower than the feed pH in two analyzed value of pH.ConclusionsThe higher flux value at pH = 9.3 is result of high content of organic matter in leachate, which is better rejected at higher pH because of higher electrostatic repulsion between organic matter and membrane surface. This indicates that the organic matter content should be taken into account when determining the operating parameters (pH values) of the RO system.

Highlights

Landfilling is still the commonly used method for final disposal of municipal solid waste [1, 2]
The landfill leachate at intermediate stage was taken into analyses
After sequencing batch reactors (SBR) pretreatment leachate characterized with good removal efficiency of N-NO3−, Biological Oxygen Demand (BOD) and N-NH4+

Summary

Introduction

Landfilling is still the commonly used method for final disposal of municipal solid waste [1, 2]. One of the main environmental problems arising during solid waste landfilling is the generation of heavily polluted landfill leachates [3] They are highly loaded wastewater containing a wide variety of pollutants, including organic compounds, heavy metals and inorganic salts [1, 3,4,5]. Biological methods give quite satisfactory performance when used for leachate from young landfill with less than 10 years of exploitation They are effective for removal of organic substances, suspended solids and nutrients [3, 8, 9]. This method is commonly used to treat landfill leachate containing high value of Biological Oxygen Demand (BOD) [1, 10]. In order to achieve high treatment efficiency, a combination of biological and

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Conclusion