Membrane Treatment of Lake Water in City Parks: A Study on Gravity-Driven Membrane Microfiltration for Urban Sustainability

Abstract

This study focuses on the feasibility of gravity-driven membrane (GDM) microfiltration (MF) as a low-energy treatment option for urban lake restoration in Lund, Sweden. Four lakes, namely Sjön Sjön, Stadsparken, Kunskapsparken Dammen, and Spexardammen, were selected based on
their varying water quality characteristics. A silicon carbide (SiC) membrane was tested in a laboratory-scale setup operated under gravity - with hydrostatic pressure only to improve the water
quality of these lakes by membrane filtration. Membrane filtration performance was assessed by monitoring flux, hydrostatic pressure, and key
water quality parameters in both feed and permeate samples. The membrane showed effective removal of turbidity and total suspended solids (TSS), with partial reductions in total organic carbon (TOC) and total nitrogen (TN). Performance varied depending on the pollution level of the
lake water samples. The Spexardammen sample exhibited a rapid flux decline due to high turbidity and organic content, while clearer samples, such as Sjön Sjön, Kunskapsparken Dammen, and Stadsparken, demonstrated more stable but generally lower fluxes, influenced by factors such as
fine particles or dissolved organics. Although the SiC membrane showed strong mechanical strength, its performance under low-
pressure, gravity-driven operation without external energy input or active backflushing (high pressure) suggests there is still room for improvement, especially in cleaning protocols and system configuration, to ensure long-term applicability. In summary, gravity-driven membrane microfiltration holds potential as a sustainable approach for urban lake water treatment, provided that membrane selection, cleaning strategies, and system design are carefully optimized.

Popular Abstract

Urban lakes are important for city life, providing spaces for recreation, biodiversity, and local climate regulation. However, many of these lakes face pollution from stormwater runoff, sediment buildup, and organic waste. In Sweden, where urban lakes are an integral part of the cultural and ecological landscape, maintaining their quality has become an increasing priority, especially as algal blooms and oxygen depletion limit public use and aquatic life.
This study investigates the potential of a simple, low-energy filtration system that could help clean lake water in Lund, Sweden, using just the force of gravity only. This technique, known as gravity-driven membrane (GDM) filtration, is a sustainable method that operates without electricity or chemical additives. It uses hydrostatic pressure to push water through a filter, much like how water seeps through soil under the influence of gravity, and operates with minimal maintenance needs.
Lake water samples were collected from four different lakes in the city, namely Sjön Sjön, Stadsparken, Kunskapsparken Dammen, and Spexardammen, and passed through a ceramic filter without any electricity or pumps. The results showed that this method can remove visible particles
and reduce water cloudiness, even from heavily polluted lakes like Spexardammen. The ceramic filter used was a flat-sheet silicon carbide (SiC) membrane with a pore size of 0.1 micrometers. It effectively removed turbidity and suspended solids. However, the membrane (ceramic filter)
performance declined over time due to fouling, likely caused by the accumulation of suspended solids on the membrane surface and a gradual drop in hydrostatic pressure during operation. To address this, various cleaning approaches were tested, including backwashing with water and chemical cleaning using sodium hydroxide and citric acid. Cleaning helped recover some of the lost performance, but regular intervention was necessary to maintain flow rates.
This research suggests that this gravity-driven filter approach has real potential for small-scale or decentralized water treatment. However, to be effective in the long run, the filter material, cleaning process, and system design must be carefully adapted to the water quality and intended use.
In summary, the findings support the idea that simple, energy-efficient technologies can play a role in maintaining urban lake ecosystems. This kind of solution could support healthier urban lakes and contribute to more sustainable water management in cities, aligning with broader environmental goals such as the UN Sustainable Development Goal 6 – clean water and sanitation.

• author: Ibeanu, Uzoma Eucharia
• supervisor: Frank Lipnizki; Tobias Hey
• organization: Chemical Engineering (M.Sc.Eng.)
• course: METM01 20251
• year: 2025
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Gravity-Driven Membrane Filtration, Silicon Carbide (SiC) Membranes, Microfiltration (MF), Urban Lake Restoration, Water Quality Improvement, Sustainable Water Treatment, Membrane Engineering
• language: English
• id: 9202943
• date added to LUP: 2025-06-19 11:23:37
• date last changed: 2025-06-19 11:23:37