Ultra-Low-Pressure Membrane Filtration for Simultaneous Recovery of Detergent and Water from Laundry Wastewater

Abstract

Reusing water and excess detergent from the laundry industry has become an attractive method to combat water shortages. Membrane filtration is considered an advanced technique and highly attractive due to its excellent advantages. However, the conventional membrane filtration method suffers from membrane fouling, which restricts its performance and diminishes its economic viability. This study assesses the preliminary performance of submerged, gravity-driven membrane filtration—under ultra-low trans-membrane pressure (△P) of <0.1 bar—to combat membrane fouling issues for detergent and water recovery from laundry wastewater. The results show that even under ultra-low pressure, the membrane suffered from compaction that lowered its permeability by 14% under △P of 6 and 10 kPa, with corresponding permeabilities of 2085 ± 259 and 1791 ± 42 L/(m2 h bar). Filtration of a detergent solution also led to up to 8% permeability loss due to membrane fouling. During the filtration of laundry wastewater, 80–91% permeability loss was observed, leading to the lowest flux of 15.6 L/(m2·h) at △P of 10 kPa, 38% lower than △P of 6 kPa (of 25.2 L/(m2·h)). High △P led to both the membrane and the foulant compaction inflating the filtration resistance. The system could recover 83.6% of excess residual detergent, while most micelles were rejected (ascribed from 71% of COD removal). The TDS content could not be retained, disallowing maximum resource recovery. A gravity-driven filtration system can be self-sustained with minimum supervision in residential and industrial laundries. Nevertheless, a detailed study on long-term filtration performance and multiple cleaning cycles is still required in the future.

The Application of Polyethersulfone Ultrafiltration Membranes for Separation of Car Wash Wastewaters: Experiments and Modelling

“…Indeed, for UE50 and UE10 membranes, the flux decreased from 600 L/m 2 h to 272 L/m 2 h and from 208 L/m 2 h to 165 L/m 2 h, respectively. This finding substantiates previous findings in the literature [ 57 ], wherein it has been shown that detergent solution significantly reduces the flux during the UF process. According to [ 43 ], this observation can be attributed to the adsorption of surfactants on the membrane surface.…”

“…It is well known that the UF process is less effective for the retention of low molecular weight substances. With regard to surfactants, the retention degree depends on their type and concentration [ 56 , 57 ]. However, to be complete, it should be noted that after exceeding the critical micelle concentration (CMC), the formed micelles become larger, which facilitates their retention by UF membranes [ 43 , 45 ].…”

Ultra-Low Pressure Filtration Performance in Campus Domestic Waste

“…Where the results of processed wastewater are expected to be reused so that in this way it can minimize the volume of waste produced. Waste treatment can be carried out by applying an ultra-low pressure membrane filtration process with a Gravity Driven Membrane (GDM) system [9]- [11].…”

Fabrication and Characterization of PSf/GO-SiO2 Membranes as Filtration of Detergent Contaminated Water

“…From this illustration, it is expected that when performing membrane filtration, the resulting permeate is water-free from detergents. Previous research conducted by Khery et al [13] for gravity-based polyacrylonitrile ultrafiltration membranes with low pressure explained that filtration in detergent solutions has a deficiency in the membrane's permeability (water flux). This happens because the higher pressure carried out during filtration can result in foulants, so there is a decrease in permeability.…”