Hybrid Anaerobic Baffled Reactor Research Articles

Hybrid anaerobic baffled reactor for treatment of desizing wastewater

Polyvinyl alcohol-containing desizing wastewater discharged within final textile wastewater has a great impact to the environment due to its poor biodegradability. An improved lab-scale hybrid anaerobic baffled reactor was developed to treat desizing wastewater. The modification was achieved by increasing the height of hybrid anaerobic baffled reactor and application of proper effluent recycle enabled to increase the ability of entrapping microbe-rich small particles in the reactor and prompted the formation of granules. The significant difficulty in hybrid anaerobic baffled reactor operation is the slow start-up procedure, which is crucial to the overall polyvinyl alcohol-containing desizing wastewater treatment. Therefore, the ability of a hybrid anaerobic baffled reactor, treating desizing wastewater, to achieve a prompt start-up was studied at lab-scale. Results showed that inoculated with anaerobic granular sludge and adoption of effluent recycle during start-up, the system demonstrated a good performance of polyvinyl alcohol removal efficiency (above 17.2 %) and satisfactory stability of pH and alkalinity in effluent (range around 7.4-8.0 and 700-920 mg/L, respectively) and the sludge appeared obviously granulation. Thus, the prompt start-up was achieved after 60 days. The start-up strategy used for this process has achieved its goals by creating an active microbial population. The improved lab-scale hybrid anaerobic baffled reactor proved to be an efficient reactor configuration for the treatment of desizing wastewater, which favored the prompt start-up of hybrid anaerobic baffled reactor. The results also provide evidence to modify the design of anaerobic baffled reactor to improve reactor performance.

Soluble microbial products formation and their effect on trace metal availability during anaerobic degradation of sulfate laden organics

Anaerobic degradation of sulfate laden organics involves sulfide generation and release of soluble microbial products (SMP). Sulfide causes direct toxicity to microorganisms and precipitation of key metals. On the other hand, SMP helps in keeping higher soluble concentration of essential metals through complexation and alleviating sulfide toxicity. The role of SMP is well recognized in biological treatment of wastes but many issues are yet to be fully elucidated. The present paper discusses the effect of sulfide concentrations on SMP production and effect of complexation on soluble Fe, Ni, Zn and Co concentrations in laboratory scale uplflow anaerobic sludge blanket (UASB) reactor, anaerobic baffled reactor (ABR) and hybrid anaerobic baffled reactor (HABR) degrading synthetic sulfate laden organics at 35 degrees C for varying operating conditions. Results indicate increased SMP concentration with increasing sulfide concentration and significantly higher measured Fe, Ni, Zn and Co concentrations due to complexation in all three systems. Soluble Fe 0.43-0.66 mg/L; Ni 0.29-0.4 mg/L; Zn 0.15-0.19 mg/L; and Co 0.13-0.29 mg/L appears to be adequate for stable process operation and performance.

Anaerobic Degradation of Sulfate Laden Organics Employing Different Reactor System Configurations

Anaerobic degradation of sulfate laden organics has been investigated employing bench-scale models of an upflow anaerobic sludge blanket (UASB) reactor, anaerobic baffled reactor (ABR), and hybrid ABR (HABR). Results indicated chemical oxygen demand (COD) removal over 65% in all three systems at a COD∕S O4 2− ratio of 8.57–8.59. However, the performance deteriorated at a low COD∕S O4 2− ratio of 6.92–7.05 with a reduction in COD removal to 41–55%. Supplementation of limiting nutrients improved COD removal (≈94.5%) in an UASB system and indicated nutrient deficiency as a primary cause of poor performance. However, poor COD removal (45.92–56.12%) in ABR and HABR indicated a severe inhibition of microbial consortia by sulfide. This study revealed that system configuration aggravated the problem of sulfide toxicity due to sequential phase separation in ABR and HABR systems at low dissolved sulfide concentration relative to the UASB reactor, a single-phase system. Sulfate removal was over 88% in all three systems.

Effect of micro-nutrients in anaerobic degradation of sulfate laden organics

The effect of micro-nutrients, such as Fe, Ni, Zn, Co, and Mo, on anaerobic degradation of sulfate laden organics was investigated using bench-scale models of upflow anaerobic sludge blanket (UASB) reactor, anaerobic baffled reactor (ABR), and hybrid anaerobic baffled reactor (HABR), operating in varying conditions in ten phases (organic loading of 1.9–5.75 kg COD/(m3·d), sulfate loading of 0.54–1.88 kg SO42–/(m3·d), chemical oxygen demand (COD):SO42–ratio of 2.0–8.6). In the initial phase, no nutrient limitation was observed with COD removal of more than 94% in all three systems. Subsequently, increase in sulfate loading resulted in Ni and Co limitation and their supplementation restored COD removal in UASB system. However, baffled systems did not recover because of severe inhibition by sulfide. Results indicate that precipitation of nutrients could seriously deteriorate process performance, leading to failure even before sulfide concentration attains toxic level. The limitation of Fe coupled with high sulfate loading (1.88 kg SO42–/(m3·d)) resulted in growth of low-density, fragile, hollow, and granular biomass in UASB that washed out and caused process instability. Supplementation of Fe with other nutrients stabilized UASB process and also improved COD removal.Key words: anaerobic degradation, nutrients, UASB, ABR, HABR, sulfide toxicity, sulfate laden organics.

Pelletization of biomass in a hybrid anaerobic baffled reactor (HABR) treating acidified wastewater

Abstract Pelletization of biomass was observed in a hydrid anaerobic baffled reactor treating molasses wastewater. The use of highly acidic molasses wastewater as substrate resulted in pelletization of the sludge within 30 days of operation. Change of substrate from acidified molasses to protein-rich molasses did not affect the process of pelletization. The biological pellets were able to grow and maintain their sludge settling-characteristics. The pellets were formed in all the three chambers of the reactor. The predominant mathanogenic bacteria observed were Methanosarcina sp. in the first chamber and Methanothrix sp. in the rest of the reactor. Other bacteria morphologically similar to Methanobrevibacter, Methanococcus and Desulfovibrio were also observed. The reactor was able to remove 73% of soluble COD (Chemical Oxygen Demand) at the loading rate of 20 kg COD/m 3 day. Methane production rates exceeded five volumes per day per unit volume of the reactor.

The effect of hydraulic retention time on the hybrid anaerobic baffled reactor performance at constant loading

An experimental study was undertaken to determine the effect of hydraulic retention time (HRT) on a 1501 hybrid anaerobic baffled reactor (HABR) at constant organic loading 10 kg m −3 d −1. When the HRT was gradually changed from 1 day to 6 days, i.e. the feed concentration changed from 10 g 1 −1 to 60 g 1 −1 the COD reduction dropped from 75% to about 40%, the gas production rate decreased from 5.2 m 3 m 3 d −1 to 3.4 m 3 m 3 d −1, and the effluent volatile fatty acids (VFA) concentration increased from 430 mg 1 −1 to about 16,000 mg l −1 Thus methanogenic inhibition occurred at longer HRTs. The experimental results strongly suggested that the HRT is a significant factor for HABR performance.

Anaerobic digestion of high strength molasses wastewater using hybrid anaerobic baffled reactor

The anaerobic digestion of high strength molasses wastewater (molasses alcohol stillage and raw molasses) in a hybrid anaerobic baffled reactor was studied. At an organic loading rate of 20 kg COD/m 3-day, the reactor performed effectively achieving total and soluble COD removals in excess of 70%. Granulation of biomass was observed in the reactor and the granules grew in size with time as the experiment progressed. The predominant methanogens similar to Methanothrix and Methanosarcina species were observed in the granules. Nitrogen and phosphorous were supplemented whenever needed. Biomass retention inside the reactor was very good. Gas production was 5 v/v of the reactor·day.

Model evaluation of hybrid anaerobic baffled reactor treating molasses wastewater

The anaerobic treatment of high strength molasses wastewater (molasses alcohol stillage and raw molasses) in a 1501 working volume hybrid anaerobic baffled reactor (HABR) was studied. At an organic loading rate of 20 kg −1 COD/m 3 day, the reactor achieved total and soluble COD removals in excess of 70%. Gas production rates exceeded five volumes per day per unit volume of reactor. A mathematical model of the baffled reactor performance was developed using a concept of completely mixed reactors operated in series. The kinetic analysis focused on the granular sludge bed, with total mass of granular sludge as the main parameter. The model results were in good agreement with experimental data. This kinetic analysis approach may be applicable for other kinds of blanket anaerobic reactors.