Membrane distillation: Solar and waste heat driven demonstration plants for desalination

Abstract

The development of small to medium size, autonomous and robust desalination units is needed to establish an independent water supply in remote areas. This is the motivation for research on alternative desalination processes. Membrane distillation (MD) seems to meet the specific requirements very well. This work is focused on experimental studies on full scale demonstration systems, utilizing a parallel multi MD-module setup. Three different plant concepts are introduced, one of them is waste heat driven and two of them are powered by solar thermal collectors. Design parameters and system design are presented. After the analysis of plant operation a comparison among the plants as well as a comparison with laboratory experiments is carried out and discussed. Impact of different feed flow rates, salinities, operating hours and process temperatures are taken into consideration and put into relation. GOR values and specific thermal heat demand are derived and compared. Energy balances of all three plants are given, uncovering heat losses and identifying room for improvement.

A perspective on reverse osmosis water desalination: Quest for sustainability

“…The remaining 14% of the capacity include multiple effect distillation, vapor compression, and electrodialysis (ED)/ED reversal (EDR). Other desalination technologies have also been proposed in recent years including, at a smaller scale, membrane distillation 25 and forward osmosis. [26][27][28] The total water desalination capacity in the United States is about 4.5 million m 3 /day 29 with most being inland BW desalination with the majority via RO technology.…”

Optimising thermal efficiency of direct contact membrane distillation by brine recycling for small-scale seawater desalination

“…The vapour pressure of pure water at the membrane surface can be calculated using the Antoine equation: (5) where P 0 is in Pa and T is the temperature in K. For a saline solution, the presence of salts in the solution reduces water activity and, hence, water vapour pressure. Thus, the partial vapour pressure of water at the membrane surfaces in DCMD of saline solutions (P) is calculated as [29]:…”

“…Indeed, RO requires intensive pre-treatment, high-pressure pumps, and duplex stainless steel piping, all of which are expensive and not practical for small-scale seawater desalination [3,4]. In the context of smallscale seawater desalination, membrane distillation (MD) can be a favourable alternative particularly because of the potential to directly use solar thermal and low-grade heat as the primary source of energy [5,6]. Unlike conventional thermal distillation processes, which require a large physical footprint, MD can retain most positive attributes of a typical membrane process, including modulation, compactness, and process efficiency [7,8].…”

Review of membrane distillation process for water purification

“…Some of the studies on solar MD are found based on lab-and pilot-scale [146][147][148][149][150][151][152][153][154][155][156]. But few of them are compared with known and well-liked solar-driven RO process.…”