A novel hybrid anaerobic-contact oxidation biofilm baffled reactor (HAOBR) was developed to simultaneously remove nitrogenous and carbonaceous organic pollutants from decentralized molasses wastewater in the study. The study was based on the inoculation of anaerobic granule sludge in anaerobic compartments and the installation of combination filler in aerobic compartments. The performance of reactor system was studied regarding the hydraulic retention time (HRT), microbial characteristics and the gas water ratio (GWR). When the HRT was 24h and the GWR was 20:1, total ammonia and chemical oxygen demand (COD) of the effluent were reduced by 99% and 91.8%, respectively. The reactor performed stably for treating decentralized molasses wastewater. The good performance of the reactor can be attributed to the high resistance of COD and hydraulic shock loads. In addition, the high solid retention time of contact oxidation biofilm contributed to stable performance of the reactor. 相似文献
• Two IFAS and two MBBR full-scale systems (high COD:N ratio 8:1) were characterized.• High specific surface area carriers grew and retained slow-growing nitrifiers.• High TN removal is related to high SRT and low DO concentration in anoxic tanks. The relative locations of AOB, NOB, and DNB were examined for three different kinds of carriers in two types of hybrid biofilm process configurations: integrated fixed-film activated sludge (IFAS) and moving bed biofilm reactor (MBBR) processes. IFAS water resource recovery facilities (WRRFs) used AnodkalnessTM K1 carriers (KC) at Broomfield, Colorado, USA and polypropylene resin carriers (RC) at Fukuoka, Japan, while MBBR WRRFs used KC carriers at South Adams County, Colorado, USA and sponge carriers (SC) at Saga, Japan. Influent COD to N ratios ranged from 8:1 to 15:1. The COD and BOD removal efficiencies were high (96%–98%); NH4+-N and TN removal efficiencies were more varied at 72%–98% and 64%–77%, respectively. The extent of TN removal was higher at high SRT, high COD:N ratio and low DO concentration in the anoxic tank. In IFAS, RC with high specific surface area (SSA) maintained higher AOB population than KC. Sponge carriers with high SSA maintained higher overall bacteria population than KC in MBBR systems. However, the DNB were not more abundant in high SSA carriers. The diversity of AOB, NOB, and DNB was fairly similar in different carriers. Nitrosomonas sp. dominated over Nitrosospira sp. while denitrifying bacteria included Rhodobacter sp., Sulfuritalea sp., Rubrivivax sp., Paracoccus sp., and Pseudomonas sp. The results from this work suggest that high SRT, high COD:N ratio, low DO concentration in anoxic tanks, and carriers with greater surface area may be recommended for high COD, BOD and TN removal in WRRFs with IFAS and MBBR systems. 相似文献
• A Passive Aeration Ditch was developed to treat decentralized wastewater.• A model was developed to describe the process performance.• A high C/N ratio facilitates microbial growth but nitrification deteriorates.• A high salinity decreases both organic and nitrogen contaminants removal. Decentralized wastewater containing elevated salinity is an emerging threat to the local environment and sanitation in remote coastal communities. Regarding the cost and treatment efficiencies, we propose a passive aeration ditch (PAD) using non-woven polyester fabric as a feasible bubbleless aerator and biofilm carrier for wastewater treatment. Consideration has been first given to PAD’s efficacy in treating saline decentralized wastewater, and then to the impact of chemical oxygen demand-to-nitrogen (C/N) ratio and salinity on biofilm formation. A multispecies model incorporating the salinity effect has been developed to depict the system performance and predict the microbial community. Results showed that the PAD system had great capacity for pollutants removal. The biofilm thickness increased at a higher C/N ratio because of the boost of aerobic heterotrophs and denitrifying bacteria, which consequently improved the COD and total nitrogen removal. However, this led to the deterioration of ammonia removal. Moreover, while a higher salinity benefited the biofilm growth, the contaminant removal efficiencies decreased because the salinity inhibited the activity of aerobic heterotrophs and reduced the abundance of nitrifying bacteria inside the biofilm. Based on the model simulation, feed water with salinity below 2% and C/N ratio in a range of 1 to 3 forms a biofilm that can reach relatively high organic matter and ammonia removal. These findings not only show the feasibility of PAD in treatment of saline decentralized wastewater, but also offer a systematic strategy to predict and optimize the process performance. 相似文献
River waters in China have dual contamination by nutrients and recalcitrant organic compounds. In principle, the organic compounds could be used to drive denitrification of nitrate, thus arresting eutrophication potential, if the recalcitrant organics could be made bioavailable. This study investigated the potential to make the recalcitrant organics bioavailable through photocatalysis. Batch denitrification tests in a biofilm reactor demonstrated that dual-contaminated river water was short of available electron donor, which resulted in low total nitrogen (TN) removal by denitrification. However, the denitrification rate was increased significantly by adding glucose or by making the organic matters of the river water more bioavailable through photocatalysis. Photocatalysis for 15 min increased the Chemical Oxygen Demand (COD) of the river water from 53 to 84 mg·L-1 and led to a 4-fold increase in TN removal. The increase in TN removal gave the same effect as adding 92 mg·L-1 of glucose. During the photocatalysis experiments, the COD increased because photocatalysis transformed organic molecules from those that are resistant to dichromate oxidation in the COD test to those that can be oxidized by dichromate. This phenomenon was verified by testing photocatalysis of pyridine added to the river water. These findings point to the potential for N removal via denitrification after photocatalysis, and they also suggest that the rivers in China may be far more polluted than indicated by COD assays. 相似文献
● MnO x /Ti flow-through anode was coupled with the biofilm-attached cathode in ECBR.● ECBR was able to enhance the azo dye removal and reduce the energy consumption.● MnIV=O generated on the electrified MnO x /Ti anode catalyzed the azo dye oxidation.● Aerobic heterotrophic bacteria on the cathode degraded azo dye intermediate products.● Biodegradation of intermediate products was stimulated under the electric field. Dyeing wastewater treatment remains a challenge. Although effective, the in-series process using electrochemical oxidation as the pre- or post-treatment of biodegradation is long. This study proposes a compact dual-chamber electrocatalytic biofilm reactor (ECBR) to complete azo dye decolorization and mineralization in a single unit via anodic oxidation on a MnOx/Ti flow-through anode followed by cathodic biodegradation on carbon felts. Compared with the electrocatalytic reactor with a stainless-steel cathode (ECR-SS) and the biofilm reactor (BR), the ECBR increased the chemical oxygen demand (COD) removal efficiency by 24 % and 31 % (600 mg/L Acid Orange 7 as the feed, current of 6 mA), respectively. The COD removal efficiency of the ECBR was even higher than the sum of those of ECR-SS and BR. The ECBR also reduced the energy consumption (3.07 kWh/kg COD) by approximately half compared with ECR-SS. The advantages of the ECBR in azo dye removal were attributed to the synergistic effect of the MnOx/Ti flow-through anode and cathodic biofilms. Catalyzed by MnIV=O generated on the MnOx/Ti anode under a low applied current, azo dyes were oxidized and decolored. The intermediate products with improved biodegradability were further mineralized by the cathodic aerobic heterotrophic bacteria (non-electrochemically active) under the stimulation of the applied current. Taking advantage of the mutual interactions among the electricity, anode, and bacteria, this study provides a novel and compact process for the effective and energy-efficient treatment of azo dye wastewater. 相似文献
Continuous pulsed plate bioreactor (PPBR) was used for phenol biodegradation.
Pseudomonas desmolyticum cells immobilized on granular activated carbon was used.
Dynamic and steady state biofilm characteristics depend on dilution rate (DR).
Lower DR favour phenol degradation and uniform, thick biofilm formation.
Exo polymeric substance production in biofilm are favoured at lower dilution rates.
Pulsed plate bioreactor (PPBR) is a biofilm reactor which has been proven to be very efficient in phenol biodegradation. The present paper reports the studies on the effect of dilution rate on the physical, chemical and morphological characteristics of biofilms formed by the cells of Pseudomonas desmolyticum on granular activated carbon (GAC) in PPBR during biodegradation of phenol. The percentage degradation of phenol decreased from 99% to 73% with an increase in dilution rate from 0.33 h?1 to 0.99 h?1 showing that residence time in the reactor governs the phenol removal efficiency rather than the external mass transfer limitations. Lower dilution rates favor higher production of biomass, extracellular polymeric substances (EPS) as well as the protein, carbohydrate and humic substances content of EPS. Increase in dilution rate leads to decrease in biofilm thickness, biofilm dry density, and attached dry biomass, transforming the biofilm from dense, smooth compact structure to a rough and patchy structure. Thus, the performance of PPBR in terms of dynamic and steady-state biofilm characteristics associated with phenol biodegradation is a strong function of dilution rate. Operation of PPBR at lower dilution rates is recommended for continuous biologic treatment of wastewaters for phenol removal. 相似文献
Quinoline (C9H7N) commonly occurs in wastewaters from the chemical, pharmaceutical, and dyeing industries. As quinoline is biodegraded, nitrogen is released as ammonium. Total-N removal requires that the ammonium-N be nitrified and then denitrified. The objective of this study was to couple quinoline biodegradation with total-N removal. In a proof-of-concept step, activated sludge was sequenced from aerobic to anoxic stages. The ammonium nitrogen released from quinoline biodegradation in the aerobic stage was nitrified to nitrate in parallel. Anoxic biodegradation of the aerobic effluent then brought about nitrogen and COD removals through denitrification. Then, simultaneous quinoline biodegradation and total-N removal were demonstrated in a novel airlift internal loop biofilm reactor (AILBR) having aerobic and anoxic zones. Experimental results showed that the AILBR could achieve complete removal of quinoline, 91% COD removal, and 85% total-N removal when glucose added as a supplemental electron donor once nitrate was formed. 相似文献
Methane production from low-strength wastewater (LSWW) is generally difficult because of the low metabolism rate of methanogens. Here, an up-flow biofilm reactor equipped with conductive granular graphite (GG) as fillers was developed to enhance direct interspecies electron transfer (DIET) between syntrophic electroactive bacteria and methanogens to stimulate methanogenesis process. Compared to quartz sand fillers, using conductive fillers significantly enhanced methane production and accelerated the start-up stage of biofilm reactor. At HRT of 6 h, the average methane production rate and methane yield of reactor with GG were 0.106 m3/(m3·d) and 74.5 L/kg COD, which increased by 34.3 times and 22.4 times respectively compared with the reactor with common quartz sand fillers. The microbial community analysis revealed that methanogens structure was significantly altered and the archaea that are involved in DIET (such as Methanobacterium) were enriched in GG filler. The beneficial effects of conductive fillers on methane production implied a practical strategy for efficient methane recovery from LSWW.