A Pervaporation Study of Ammonia Solutions Using Molecular Sieve Silica Membranes

Abstract

An innovative concept is proposed to recover ammonia from industrial wastewater using a molecular sieve silica membrane in pervaporation (PV), benchmarked against vacuum membrane distillation (VMD). Cobalt and iron doped molecular sieve silica-based ceramic membranes were evaluated based on the ammonia concentration factor downstream and long-term performance. A modified low-temperature membrane evaluation system was utilized, featuring the ability to capture and measure ammonia in the permeate. It was found that the silica membrane with confirmed molecular sieving features had higher water selectivity over ammonia. This was due to a size selectivity mechanism that favoured water, but blocked ammonia. However, a cobalt doped silica membrane previously treated with high temperature water solutions demonstrated extraordinary preference towards ammonia by achieving up to a 50,000 mg/L ammonia concentration (a reusable concentration level) measured in the permeate when fed with 800 mg/L of ammonia solution. This exceeded the concentration factor expected by the benchmark VMD process by four-fold, suspected to be due to the competitive adsorption of ammonia over water into the silica structure with pores now large enough to accommodate ammonia. However, this membrane showed a gradual decline in selectivity, suspected to be due to the degradation of the silica material/pore structure after several hours of operation.

Treatment of Gaseous Ammonia Emissions Using Date Palm Pits Based Granular Activated Carbon

“…An exponential increase both in the human population and related industrial activities, specifically in the past century, has caused a significant increase in air pollution. Consequently several stringent environmental regulations have been promulgated, which do require an appropriate treatment of gaseous emissions, including ammonia (NH 3 ), considering the respective toxicity and environmental concerns [1][2][3]. Gaseous ammonia is typically emitted from several sources including fertilizer industry [4], wastewater treatment plants [2,5], agricultural practices [6], animal feeding setups [7,8], dairy/poultry industries [9,10], composting facilities [11,12], fishmeal plants [13], gasoline vehicles [14], and from specific chemical industries [15].…”

“…Consequently several stringent environmental regulations have been promulgated, which do require an appropriate treatment of gaseous emissions, including ammonia (NH 3 ), considering the respective toxicity and environmental concerns [1][2][3]. Gaseous ammonia is typically emitted from several sources including fertilizer industry [4], wastewater treatment plants [2,5], agricultural practices [6], animal feeding setups [7,8], dairy/poultry industries [9,10], composting facilities [11,12], fishmeal plants [13], gasoline vehicles [14], and from specific chemical industries [15]. Considering the respective toxicity and health concerns, various technologies have been employed for the removal of gaseous ammonia including bio-filters [3,13,16,17], catalytic systems [18] biological treatment [11], scrubbers [5] and other specific technologies such as nano-particles applications [4].…”

Demonstration of membrane distillation on textile waste water: assessment of long term performance, membrane cleaning and waste heat integration

“…Instead of being evidence of wetting, this moderate cold cycle EC rise was more likely due to volatile ammonia and carbon dioxide (from carbonates) transport through the membrane which has been seen in previous pilot trial on ion exchange regeneration waste which was pH neutralised using sodium bicarbonate. The transport of ammonia through MD membranes [11] can also be utilised as a means to remove ammonia from wastewaters [49].…”

“…This could be expected since most of the time the membrane total production rate was close to the 'Treated MD feed' flow rate (overall recovery as mentioned earlier of 91.6%). While ammonium present in the permeate product may limit its reuse as clean water, the capacity of the system to instead capture ammonia from the wastewater as part of resource recovery and is part of our ongoing research in this area [49,51]. For ammonium to become sufficiently volatile, however, the solution pH generally needs to be increased to higher than the pH of the 'Treated MD feed' fed to the DCMD plant of 7.7 (Figure 1).…”

Effect of nanodiamond additives on the structure and gas‐transport properties of a poly(phenylene–isophtalamide) matrix

“…Inorganic particles added to a polymer matrix influence the permeability through the following effects: (1) they act as molecular sieves and alter the permeability, (2) they disrupt the polymeric structure and increase the permeability, and (3) they act as barriers reduce the permeability …”