Continuous acetonitrile degradation in a packed-bed bioreactor

Abstract

A 20-l packed-bed reactor filled with foamed glass beads was tested for the treatment of acetonitrile HPLC wastes. Aeration was provided by recirculating a portion of the reactor liquid phase through an aeration tank, where the dissolved oxygen concentration was kept at 6 mg/l. At a feeding rate of 0.77 g acetonitrile l(-1) reactor day(-1), 99% of the acetonitrile was removed; and 86% of the nitrogen present in acetonitrile was released as NH3, confirming that acetonitrile volatilization was not significant. Increasing the acetonitrile loading resulted in lower removal efficiencies, but a maximum removal capacity of 1.0 g acetonitrile l(-1) reactor day(-1) was achieved at a feeding rate of 1.6 g acetonitrile l(-1) reactor day(-1). The removal capacity of the system was well correlated with the oxygenation capacity, showing that acetonitrile removal was likely to be limited by oxygen supply. Microbial characterization of the biofilm resulted in the isolation of a Comamonas sp. able to mineralize acetonitrile as sole carbon, nitrogen and energy source. This organism was closely related to C. testosteroni (91.2%) and might represent a new species in the Comamonas genus. This study confirms the potential of packed-bed reactors for the treatment of a concentrated mixture of volatile pollutants.

Biodegradation of propionitrile by Klebsiella oxytoca immobilized in alginate and cellulose triacetate gel

“…Continuous flow column system of wastewater is a well-established method for remediation of wastes. Furthermore, some studies of large-scale or pilot-scale continuous flow column system with immobilized cells have been successfully used for the treatment of urban and industrial wastewaters containing various contaminants (e.g., acetonitrile, phenol) [22,28,49,51]. In this study, a continuousflow column system has been designed to increase the efficiency of biological treatment systems by (1) allowing greater organic loads, (2) minimizing production of sludge waste by-products, and (3) increasing process stability and resistance to shock load- ing.…”

“…Some researchers also demonstrated that the increased mechanical strength and durability for performing the aerobic and anaerobic biodegradation using cellulose triacetate as a microbial carrier [23,27]. Because of its high removal efficiency, biological treatment of wastewater using immobilized cell systems have been applied for practical application [23,[28][29][30].…”

“…In this study, K. oxytoca, known for its capability on cyanide and nitriles degradation [3,31,32], was immobilized by entrapment in AL and CT. The composite gel beads were prepared through the condensation of silane precursor in an alginate solution, followed by cross-linking with Ba 2+ [22,23] and in batch entrapment within an insoluble gel matrix [23,27,28]. As nitrile wastewater has very high organic contents, biological treatment is a suitable process to treat nitrile-containing wastewater.…”

Biofilm photobioreactors for the treatment of industrial wastewaters

“…1): a flat plate and a tubular photobioreactor with the algal-bacterial biofilm attached onto 4-8 mm Poraver ® foamed-glass beads [13], a flat plate and a tubular photobioreactor with the biofilm attached onto the bioreactor walls, an algal-turf reactor shallow open pond [14] with the biofilm attached to the reactor base, and a column photobioreactor with suspended algal-bacterial biomass and no biomass retention (chemostat operation). The main characteristics of each photobioreactors are shown in Table 1.…”

The current and future applications of microorganism in the bioremediation of cyanide contamination

“…The exploitation of immobilised bacterial systems has received considerable attention because bacteria in biofilms are more resilient to environmental insults they therefore offer an opportunity to treat more concentrated wastes streams. A biofilm containing a novel Comamonas species in a packed bed reactor demonstrated maximum acetonitrile degradation of 1 g l )1 d )1 (Manolov et al 2005). Immobilised systems also offer the potential to treat gaseous waste, R. ruber immobilised in a synthetic silicon polymer was used to treat gaseous acrylonitrile.…”