Optimization of biological nitrogen removal in full-scale municipal WWTPs using activated sludge model simulation.

The study evaluated the most efficient biological nitrogen removal (BNR) process in four full-scale municipal wastewater treatment plants (WWTPs) by using BioWin, a simulation software based on the activated sludge model (ASM). A series of experiments were conducted to determine the kinetic and stoichiometric parameters for the ASM. Results indicated that autotrophic maximum specific growth rates in the studied WWTPs were generally higher compared to previous findings, likely due to their low COD/N ratios, emphasizing the importance of local parameterization.

Performances of full-scale biological nitrogen pre-treatment process for drinking water source: Seasonal variations and microbial community.

This study investigated the performance of the full-scale unit over a two-year period to enhance nitrification efficiency and provide operational strategies. Results indicated that raw water quality from Donggan River was notably influenced by seasonal variations, particularly during dry and wet seasons, impacting the nitrification efficiency of the biological pretreatment process. Factors such as influent concentrations of ammonia and total Kjeldahl nitrogen were found to have significant effects on nitrification, with temperature and conductivity also showing correlations.

Applying metabolic flux analysis to hydrogen fermentation using a metabolic network constructed for anaerobic mixed cultures.

In this study, a mixed-cultural metabolic network for anaerobic digestion that included the concept of a "universal bacterium" was constructed, and metabolic flux analysis (MFA) applying this network was conducted to evaluate the flow of electrons and materials during H fermentation under various conditions. The MFA results from two H fermenters feeding glucose with (GP) or without (GA) the addition of peptone suggest that hydraulic retention time (HRT) presents a significant impact on hydrogen production, and the reversed trends could be observed at HRTs below and above 4 h. From the MFA results of lactate/acetate-fed H fermenter, the highest flux of H production is associated with more significant acetate consumption and the following pathways toward the anaplerotic reactions cycle that produces NADH.

Resource recovery from lignocellulosic wastes via biological technologies: Advancements and prospects.

Lignocellulosic wastes were recently considered as biomass resources, however, its conversion to valuable products is still immature although researchers have put lots of effort into this issue. This article reviews the key challenges of the biorefinery utilizing lignocellulosic materials and recent developments to conquer those obstacles. Available biological techniques and processes, from the pretreatments of cellulosic materials to the valorization processes, were emphasized.

Biological treatment of volatile organic compounds (VOCs)-containing wastewaters from wet scrubbers in semiconductor industry.

This study investigated biological treatment for two kinds of volatile organic compounds (VOCs)-containing wastewaters collected from wet scrubbers in a semiconductor industry. Batch test results indicated that one wastewater containing highly volatile organic compounds was not suitable for aerated treatment conditions while the other containing much lower volatile organic compounds was suitable for aerobic treatment. Accordingly, two moving bed bioreactors, by adding commercial biocarrier BioNET, were operated under aerobic and anoxic conditions for treating low volatility wastewater (LVW) and high volatility wastewater (HVW), respectively.

Effects of copper on biological treatment of NMF- and MDG-containing wastewater from TFT-LCD industry.

This study aimed to evaluate the effects of copper on N-methylformamide (NMF)- and methyl diglycol (MDG)-containing wastewater treatment using batch experiments and a lab-scale anoxic-oxic (A/O) sequencing batch reactor (SBR). Batch experimental results indicated that aerobic degradation of NMF followed Monod-type kinetics. Copper inhibition on nitrification also followed Monod-type inhibition kinetics with copper-to-biomass ratio instead of copper concentration.

Nitrogen removal as nitrous oxide for energy recovery: Increased process stability and high nitrous yields at short hydraulic residence times.

The Coupled Aerobic-anoxic Nitrous Decomposition Operation (CANDO) is a two-stage process for nitrogen removal and resource recovery: in the first, ammonia is oxidized to nitrite in an aerobic bioreactor; in the second, oxidation of polyhydroxyalkanoate (PHA) drives reduction of nitrite to nitrous oxide (NO) which is stripped for use as a biogas oxidant. Because ammonia oxidation is well-studied, tests of CANDO to date have focused on NO production in anaerobic/anoxic sequencing batch reactors. In these reactors, nitrogen is provided as nitrite; PHA is produced from acetate or other dissolved COD, and PHA oxidation is coupled to NO production from nitrite.

Recent advancement on biological technologies and strategies for resource recovery from swine wastewater.

Swine wastewater is categorized as one of the agricultural wastewater with high contents of organics and nutrients including nitrogen and phosphorus, which may lead to eutrophication in the environment. Insufficient technologies to remove those nutrients could lead to environmental problems after discharge. Several physical and chemical methods have been applied to treat the swine wastewater, but biological treatments are considered as the promising methods due to the cost effectiveness and performance efficiency along with the production of valuable products and bioenergies.

Biological treatment of DMSO-containing wastewater from semiconductor industry under aerobic and methanogenic conditions.

This study evaluated biological treatment of dimethyl sulfoxide (DMSO)-containing wastewater from semiconductor industry under aerobic and anaerobic conditions. DMSO concentration as higher as 1.5 g/L did not inhibit DMSO degradation efficiency in aerobic membrane bioreactor (MBR), while specific DMSO degradation rate at different initial DMSO-to-biomass (S/X) ratios from batch tests seemed to follow the Haldane-type kinetics.

Pilot study of cold-rolling wastewater treatment using single-stage anaerobic fluidized membrane bioreactor.

A pilot-scale single-stage anaerobic fluidized membrane bioreactor (AFMBR) was firstly used in this study to treat cold-rolling emulsion wastewater from steel industry. It was continuously operated for 302 days with influent COD concentration of 860-1120 mg/L. Under a hydraulic retention time of 1.

Biological acetate production from carbon dioxide by Acetobacterium woodii and Clostridium ljungdahlii: The effect of cell immobilization.

This study investigated the acetate production from gas mixture of hydrogen (H) and carbon dioxide (CO) in the ratio of 7:3 using two acetogens: Acetobacterium woodii and Clostridium ljungdahlii. Batch result shows A. woodii performed two-phase degradation with the presence of glucose that lactate was produced from glucose and was reutilized for the production of butyrate and few acetate, while only acetate was detected when providing gas mixture.

Biological hydrogen and methane production from bagasse bioethanol fermentation residues using a two-stage bioprocess.

This study investigated the recovery of H2 and CH4 from bagasse bioethanol fermentation residues (bagasse BEFR) using a two-stage bioprocess. In the hydrogen fermentation bioreactor (HFB), carbohydrate removal efficiency was maintained at 82-93% and the highest hydrogen yield was 8.24mL/gCOD at volumetric loading rate (VLR) of 80kgCOD/m(3)/day.

Enhanced bioenergy recovery from oil-extracted microalgae residues via two-step H2/CH4 or H2/butanol anaerobic fermentation.

Algae-based biodiesel is considered a promising alternative energy; therefore, the treatment of microalgae residues would be necessary. Anaerobic processes can be used for treating oil-extracted microalgae residues (OMR) and at the same time for recovering bioenergy. In this study, anaerobic batch experiments were conducted to evaluate the potential of recovering bioenergy, in the forms of butanol, H2, or CH4, from pretreated OMR.

Biological butanol production from microalgae-based biodiesel residues by Clostridium acetobutylicum.

This study conducted batch experiments to evaluate the potential of butanol production from microalgae biodiesel residues by Clostridium acetobutylicum. The results indicated that with 90 g/L of glucose as the sole substrate the highest butanol yield of 0.2 g/g-glucose was found, but the addition of butyrate significantly enhanced the butanol yield.

Fermentative biohydrogen production from lactate and acetate.

In this study, a continuous-flow stirred tank reactor (CSTR) fed with lactate and acetate was operated to enrich hydrogen-producing bacteria. By varying the influent substrate concentrations and hydraulic retention times (HRT), the volumetric loading rate (VLR) of 55.64 kg-COD/m(3)/day seemed to be optimum for this enriched culture for fermentative hydrogen production from lactate and acetate.

A two-stage bioprocess for hydrogen and methane production from rice straw bioethanol residues.

This study evaluates a two-stage bioprocess for recovering hydrogen and methane while treating organic residues of fermentative bioethanol from rice straw. The obtained results indicate that controlling a proper volumetric loading rate, substrate-to-biomass ratio, or F/M ratio is important to maximizing biohydrogen production from rice straw bioethanol residues. Clostridium tyrobutyricum, the identified major hydrogen-producing bacteria enriched in the hydrogen bioreactor, is likely utilizing lactate and acetate for biohydrogen production.

Metabolic and energetic aspects of biohydrogen production of Clostridium tyrobutyricum: The effects of hydraulic retention time and peptone addition.

This study evaluates the microbial metabolism and energy demand in fermentative biohydrogen production using Clostridium tyrobutyricum FYa102 at different hydraulic retention times (HRT) over a period of 1-18 h. The hydrogen yield shows a positive correlation with the butyrate yield, the B/A ratio, and the Y(H2)/2(Y(HAc)+Y(HBu)) ratio, but a negative correlation with the lactate yield. A decrease in HRT, which is accompanied by an increased biomass growth, tends to decrease the B/A ratio, due presumably to a higher energy demand for microbial growth.

Evaluation of bioenergy recovery processes treating organic residues from ethanol fermentation process.

This study evaluates a two-stage bioprocess for recovering bioenergy in the forms of hydrogen and methane while treating organic residues of ethanol fermentation from tapioca starch. A maximum hydrogen production rate of 0.77 mmol H(2)/g VSS/h can be achieved at volumetric loading rate (VLR) of 56 kg COD/m(3)/day.