Behavior of total phosphorus removal in an intelligent controlled sequencing batch biofilm reactor for municipal wastewater treatment

Sulfur-based Mixotrophic Vanadium (V) Bio-reduction towards Lower Organic Requirement and Sulfate Accumulation

Although remediation of toxic vanadium (V) [V(V)] pollution can be achieved through either heterotrophic or sulfur-based autotrophic microbial reduction, these processes would require a large amount of organic carbons or generate excessive sulfate. This study reported that by using mixotrophic V(V) bio-reduction with acetate and elemental sulfur [S(0)] as joint electron donors, V(V) removal performance was enhanced due to cooccurrence of heterotrophic and autotrophic activities. Deposited vanadium (IV) was identified as the main reduction product by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Based on 16S rRNA gene amplicon sequencing, qPCR and genus-specific reverse transcription qPCR, it was observed that V(V) was likely detoxified by heterotrophic V(V) reducers (e.g., Syntrophobacter, Spirochaeta and Geobacter). Cytochrome c, intracellular nicotinamide adenine dinucleotide and extracellular polymeric substances were involved in V(V) reduction and binding. Organic metabolites synthesized by autotrophs (e.g., Thioclava) with energy from S(0) oxidation might compensate electron donors for heterotrophic V(V) and sulfate reducers. Less sulfate was accumulated presumably due to activities of sulfur-respiring genera (e.g., Desulfurella). This study demonstrates mixotrophic microbial V(V) reduction can save organic dosage and avoid excessive sulfate accumulation, which will be beneficial to bioremediation of V(V) contamination.

A review for tannery wastewater treatment: some thoughts under stricter discharge requirements

To meet the extremely strict requirements of tannery wastewater, scientists need to urgently devise novel methods for controlling the quality of tannery wastewater. With these methods, it would be easier to promote sustainable development in the tannery industry. In this article, we summarize the following aspects of tannery wastewater: (i) the sources and characteristics of tannery wastewater, (ii) the main treatment methods (primary, secondary, and tertiary treatments), and (iii) resource utilization status of wastewater. In a brief introduction, we describe how tannery wastewater is currently subjected to single-pollutant treatment methods that strive to remove various toxic chemicals, including total nitrogen, total phosphorus, chloride ion, chromic salts, sulfur-containing compounds, and dyes. The methods for treating tannery wastewater is proposed. We anticipate that by using a proposed combination treatment techniques, the effluents in tannery wastewater can eventually be controlled to satisfy the stricter standards of wastewater disposal. Moreover, we also focus our efforts on recycling wastewater.

Granulation of activated sludge using butyrate and valerate as additional carbon source and granular phosphorus removal capacity during wastewater treatment

As an efficient and low-cost phosphorus (P) removal method from wastewater, enhanced biological phosphorus removal process always faces the insufficient carbon source issue. In this study, two identical sequencing batch reactors were used to cultivate aerobic granular sludge, in which butyrate (Rb) and valerate (Rv), two major volatile fatty acids that can be produced from anaerobic fermentation of waste biomass, were respectively applied as additional carbon source. Both reactors exhibited almost same excellent organics and total nitrogen removals during 120 days' operation, about 95.2-95.7% and 67.9-68.0% respectively with noticeable difference in P removal. Compared to the granules in Rv (24.3 mg P/g-total solids), bigger and more stable ones with higher P removal capacity (11.5 mg P/g-volatile solids∙d) were finally achieved in Rb, containing higher P content (36.0 mg P/g-total solids) with more orthophosphate and polyphosphate accumulated. Microbial community analysis reflected more polyphosphate-accumulating organisms (Rhodocyclus-related bacteria and Actinobacteria) in the granules from Rb.

Enhanced alure-type biological system (E-ATBS) for carbon, nitrogen and phosphorus removal from slaughterhouse wastewater: A case study

Slaughterhouse wastewater is one of the most harmful agriculture and food industrial wastewaters. The emissions of not fully treated slaughtering wastewater would cause eutrophication of surface water and pollution of groundwater. This study investigated the nutrient removal performance for the enhanced alure-type biological system (E-ATBS) in the full-scale application. During the whole study period, COD, TN and TP removal efficiencies were higher than 97.1%, 90.8% and 90.1%, respectively. The effluent concentrations were lower than the newest effluent standard in China to avoid the discharged water pollution. Partial denitrification (PD)-ANAMMOX was considered as the main approach for anaerobic NH₄⁺-N removal, which helped to guarantee the efficient N removal in the full-scale E-ATBS. Denitrifying P removal and aerobic P uptake ensured the efficient and stable P removal. E-ATBS is a promising technology especially for wastewater treatment in food processing facilities and should be widely popularized.

Effect of air flow rate and C/N ratio on biological nitrogen removal through the CANON process treating reject water

The CANON process is a promising method for nitrogen removal in wastewaters with low organic carbon content like reject water. This study investigated the effect of important factors for optimization of the CANON process through inhibition of nitrite-oxidizing bacteria (NOB). In the acclimation period, complete ammonium removal and 43.3% total N removal were obtained at hydraulic retention time of 12 h, temperature of 30°C ± 0.5°C and DO equal to 7-9 mg/L. The effects of air flow rate (AFR) (representative of DO), SRT and C/N were evaluated. Air flow rate was the most important factor for controlling the process, but the effect of SRT was negligible. When AFR was increased from 100 to 500 mL/min, both ammonium removal efficiency (33-43% to 81-83%) and nitrite accumulation (nitritation, 40 mgN/L to 100-120 mgN/L) were increased, but with increasing AFR to 1000 mL/min only ammonium removal efficiency was increased and because of better condition (high DO) for NOBs, nitritation was decreased. C/N had an effect like AFR of 1000 and only increased ammonium removal efficiency and total N removal. With increasing AFR and C/N, both OUR and AUR were increased, but SVI was decreased.

A study on the use of the BioBall® as a biofilm carrier in a sequencing batch reactor

Described in this study are experiments conducted to evaluate the removal of organics and nutrients from synthetic wastewater by a moving bed sequencing batch biofilm reactor using BioBall® carriers as biofilm media. The work involving a 15L-laboratory scale MBSBBR (moving bed sequencing batch biofilm reactor) model showed that the wastewater treatment system was based on biochemical processes taking place with activated sludge and biofilm microorganisms developing on the surface of the BioBall® carriers. Classical nitrification and denitrification and the typical enhanced biological phosphorus removal process were achieved in the reactor analyzed, which operated with a volumetric organic loading of 0.84-0.978gCODL(-1)d(-1). The average removal efficiencies for COD, total nitrogen and total phosphorus were found to be 97.7±0.5%, 87.8±2.6% and 94.3±1.3%, respectively. Nitrification efficiency reached levels in the range 96.5-99.7%.

Microbial communities, extracellular proteomics and polysaccharides: A comparative investigation on biofilm and suspended sludge

Biofilm and suspended sludge (S-sludge) floc exhibit distinct physicochemical properties and process performances in an integrated fixed-film and suspended growth sequencing batch reactor. However, the mechanisms of governing these differences between the two aggregates were unknown. Current work evaluated the diversity of morphologies, microbial communities, extracellular proteins and polysaccharides between the biofilm and S-sludge. Contrast to biofilm, the denitrification was much more extensive performed in S-sludge. Furthermore, many microbial cells in the biofilm acted as the backbone of aggregates and maintained the structure stability. An extracellular protein observed only in the biofilm can promote the cell adhesion. In contrast, more extracellular proteins related to catalytic activity in the S-sludge could decrease the compactness of floc. In addition, the monosaccharide compositions from the two aggregates were various. These results could elucidate how the diversities of architecture and biochemical process between the two aggregates occurred.

Performance evaluation of enhanced SBR in simultaneous removal of nitrogen and phosphorous

BACKGROUND

Simultaneous nitrogen, phosphorous and COD removal in a pilot-scale enhanced Sequencing Batch Reactor (eSBR) was investigated.

METHODS

The reactor consisted of a pre-anoxic zone and internal recycle and was fed with synthetic wastewater. The study was performed by operating the reactor in 6-hour cycles in three different operational modes during a time frame of 279 days.

RESULTS

Under the best operational conditions, the average removal rate of COD, TN, and TP were obtained as 93.52, 88.31, and 97.56%, respectively.

CONCLUSIONS

A significant denitrifying phosphorus removal (more than 80%) occurred at run1 and 3 which started the cycle under anoxic condition.

Removing and Recovering Phosphate from Poultry Wastewater Using Amorphous Ceramics

A novel and effective technique for phosphate from poultry wastewater was developed using amorphous ceramics. Amorphous ceramics, which showed high performance for phosphate removal and recovery from poultry wastewater, were synthesized using unlimitedly available, inexpensive materials such as silica fume and lime. Dissolved phosphate in poultry wastewater can be deposited as a solid on the surface of amorphous ceramics. Phosphate content on the surface of amorphous ceramics could reach 14.20%. The phosphate removal and recovery process and mechanism was revealed by a series of characterizations, such as XRD, FESEM, BET, and so on. The present study demonstrated that amorphous ceramics have great potential as a novel, beneficial material for removing and recovering phosphate from poultry wastewater.

Synthesis and Enhanced Phosphate Recovery Property of Porous Calcium Silicate Hydrate Using Polyethyleneglycol as Pore-Generation Agent

The primary objective of this paper was to synthesize a porous calcium silicate hydrate (CSH) with enhanced phosphate recovery property using polyethyleneglycol (PEG) as pore-generation agent. The formation mechanism of porous CSH was proposed. PEG molecules were inserted into the void region of oxygen-silicon tetrahedron chains and the layers of CSH. A steric hindrance layer was generated to prevent the aggregation of solid particles. A porous structure was formed due to the residual space caused by the removal of PEG through incineration. This porous CSH exhibited highly enhanced solubility of Ca²⁺ and OH^- due to the decreased particle size, declined crystalline, and increased specific surface area (S_BET) and pore volume. Supersaturation was increased in the wastewater with the enhanced solubility, which was beneficial to the formation of hydroxyapatite (HAP) crystallization. Thus, phosphate can be recovered from wastewater by producing HAP using porous CSH as crystal seed. In addition, the regenerated phosphate-containing products (HAP) can be reused to achieve sustainable utilization of phosphate. The present research could provide an effective approach for the synthesis of porous CSH and the enhancement of phosphate recovery properties for environmental applications.