Treatment of metalworking fluids using a submerged anaerobic membrane bioreactor (SAMBR)

Abstract

BACKGROUND: The role of biodegradation and physical-chemical mechanisms involved in the treatment of metal working fluids (MWFs) using a submerged anaerobic membrane bioreactor (SAMBR) was assessed in this research. Two SAMBRs were employed in series, with the second SAMBR being fed the permeate from the first bioreactor. RESULTS: Results showed a low biodegradability of the MWF both in batch tests (bioconversion efficiency ≤ 3%), and operating the bioreactors continuously (bioconversion efficiency ∼0%).Among the physical-chemical removal mechanisms identified, it was found that bio-adhesion was the most important in MWF removal (removal rate of 96.0 ± 1.64%), whereas membrane rejection was not significant (removal rate of 0.2 ± 0.18%). However, it is expected that membrane separation will play an important role in removal after bio-adhesion has been saturated. CONCLUSION:The inhibition of the hydrolytic/heteroacetogenic biomass was the most problematic aspect in anaerobic digestion, resulting in the need for bioaugmentation of specific microorganisms to degrade MWFs. In the case of non-adaptation during long-term operation, the bio-adhesive propensity of MWFs could be used as a potential method for removing spent MWFs from wastewater streams. Figure 2. Cumulative methane production detected in BMP assays. Data are shown as mean ± standard deviation.

Bioremediation Of A Spent Metalworking Fluid With Auto- And Allochthonous Bacterial Consortia

“…Bioremediation of recalcitrant MWF constituents was shown to be effective either with aerobic or anaerobic methods [9,14,39,49]. However, in general the aerobic process, as compared to the anaerobic one, resulted in better COD removal rates and higher contribution of biodegradation mechanism [14,50]. It thus appears that the anaerobic treatment technology requires further optimization actions such as supplementation with complementary physical-chemical processes, addition of co-substrates and/or extensive bioaugmentation [50,51].…”

Selection and assembly of indigenous bacteria and methanogens from spent metalworking fluids and their potential as a starting culture in a fluidized bed reactor

“…Anaerobic toxicity tests (ATA) showed that acetic acid was completely converted to methane at 0.5% and 1% of fresh MWF, but bioconversion ‘lagged’ by approximately 7 and 15 days respectively. However, at 2% fresh MWF did not show any significant generation over a period of 175 days (Teli et al ., ). In the same study, Teli et al .…”

“…In the same study, Teli et al . () found very low biodegradation of fresh MWF in submerged anaerobic membrane bioreactors. In this study, the mechanisms for COD removal included bio‐adhesion of the MWF to anaerobic biomass, whereas COD membrane rejection was not significant.…”

“…Teli et al . () used a biochemical methane potential (BMP) test and found a minor production of methane over a period of approximately 150 days when starting with 0.5% of fresh MWF. Anaerobic toxicity tests (ATA) showed that acetic acid was completely converted to methane at 0.5% and 1% of fresh MWF, but bioconversion ‘lagged’ by approximately 7 and 15 days respectively.…”

“…These archaea, however, are known to be sensitive to chemical challenges, and the introduction of waste MWFs into anaerobic digesters has been shown to have highly deleterious effects on the production of methane (Perez et al, 2006). Teli et al (2015) used a biochemical methane potential (BMP) test and found a minor production of methane over a period of approximately 150 days when starting with 0.5% of fresh MWF. Anaerobic toxicity tests (ATA) showed that acetic acid was completely converted to methane at 0.5% and 1% of fresh MWF, but bioconversion 'lagged' by approximately 7 and 15 days respectively.…”