Pilot-scale waste activated sludge alkaline fermentation, fermentation liquid separation, and application of fermentation liquid to improve biological nutrient removal

The use of sludge fermentative short-chain fatty acids (SCFA) as an additional carbon source of biological nutrient removal (BNR) has drawn much attention recently as it can reuse sludge organics, reduce waste activated sludge production, and improve BNR performance. Our previous laboratory study had shown that the SCFA production was significantly enhanced by controlling sludge fermentation at pH 10 with NaOH. This paper focused on a pilot-scale study of alkaline fermentation of waste activated sludge, separation of the fermentation liquid from the alkaline fermentation system, and application of the fermentation liquid to improve municipal biological nitrogen and phosphorus removal. NaOH and Ca(OH)(2) were used respectively to adjust the alkaline fermentation pH, and their effects on sludge fermentation and fermentation liquid separation were compared. The results showed that the use of Ca(OH)(2) had almost the same effect on SCFA production improvement and sludge volatile suspended solids reduction as that of NaOH, but it exhibited better sludge dewatering, lower chemical costs, and higher fermentation liquid recovery efficiency. When the fermentation liquids, adjusted with Ca(OH)(2) and NaOH respectively, were added continuously to an anaerobic-anoxic-aerobic municipal wastewater BNR system, both the nitrogen and phosphorus removals, compared with the control, were improved to the same levels. This was attributed to the increase of not only influent COD but also denitrifying phosphorus removal capability. It seems that the use of Ca(OH)(2) to control sludge fermentation at pH 10 for efficiently producing a carbon source for BNR is feasible.     

Nitrogen removal via nitrite from municipal wastewater at low temperatures using real-time control to optimize nitrifying communities

Although many studies regarding nitrogen removal via nitrite have been carried out, very limited research has been undertaken on nitrogen removal via nitrite at low temperatures. In this study, to improve the nitrogen removal efficiency from municipal wastewater, a pilot-plant of sequencing batch reactor with a working volume of 54 m3 was used to investigate nitrogen removal via nitrite from municipal wastewater at normal and low water temperature. The obtained results showed that high nitrogen removal efficiency with effluent total nitrogen below 3 mg/L could be achieved. Using real-time control with temperature ranging from 11.9 to 26.5 degrees C under normal dissolved oxygen condition (> or =2.5 mg/L), nitrogen removal via nitrite was successfully and stably achieved for a long period (180 days) with average nitrite accumulation rate above 95%. Fluorescence in situ hybridization was carried out to investigate the quantitative changes of nitrifying microbial community in the activated sludge. Fluorescence in situ hybridization results approved that the nitrifying microbial communities were optimized; ammonia oxidizing bacteria became the dominant nitrifying bacteria and nitrite oxidizing bacteria had been washed out of the activated sludge.     

Enhanced biological phosphorus removal driven by short-chain fatty acids produced from waste activated sludge alkaline fermentation

This paper examines the feasibility of using alkaline fermentative short-chain fatty acids (SCFAs) as the carbon sources of enhanced biological phosphorus removal (EBPR) microorganisms. First, the released phosphorus was recovered from the SCFA-containing alkaline fermentation liquid by the formation of struvite precipitation, and 92.8% of the soluble ortho-phosphorus (SOP) could be recovered under conditions of Mg/P = 1.8 (mol/mol), pH 10.0, and a reaction time of 2 min. One reason for a Mg addition required in this study that was higher than the theoretical value was thatthe organic compounds consumed Mg. Then, two sequencing batch reactors (SBRs) were operated, respectively, with acetic acid and alkaline fermentative SCFAs as the carbon source of EBPR. The transformations of SOP, polyhydroxyalkanoates (PHAs), and glycogen and the removal of phosphorus were compared between two SBRs. It was observed that the phosphorus removal efficiency was around 98% with the fermentative SCFAs, and about 71% with acetic acid, although the former showed much lower transformations of both PHAs and glycogen. The reasons that fermentative SCFAs caused much higher SOP removal than acetic acid were due to less PHAs used for glycogen synthesis and a higher PHA utilization efficiency for SOP uptake. Finally, the toxicity of fermentation liquid to EBPR microorganisms was examined, and no inhibitory effect was observed. It can be concluded from this studythatthe SCFAs from alkaline fermentation of waste activated sludge were a superior carbon source for EBPR microorganisms than pure acetic acid.     

Long-term effects of titanium dioxide nanoparticles on nitrogen and phosphorus removal from wastewater and bacterial community shift in activated sludge

The expanding use of titanium dioxide nanoparticles (TiO(2) NPs) in a wide range of fields raises concerns about their potential environmental impacts. However, investigations of the potential effects of TiO(2) NPs on biological nitrogen and phosphorus removal and bacterial community in activated sludge are sparse. This study evaluated the influences of TiO(2) NPs on biological nutrient removal in the anaerobic-low dissolved oxygen (0.15-0.50 mg/L) sequencing batch reactor. It was found that 1 and 50 mg/L TiO(2) NPs had no acute effects on wastewater nitrogen and phosphorus removal after short-term exposure (1 day). However, 50 mg/L TiO(2) NPs (higher than its environmentally relevant concentration) was observed to significantly decrease total nitrogen (TN) removal efficiency from 80.3% to 24.4% after long-term exposure (70 days), whereas biological phosphorus removal was unaffected. Denaturing gradient gel electrophoresis profiles showed that 50 mg/L TiO(2) NPs obviously reduced the diversity of microbial community in activated sludge, and fluorescence in situ hybridization analysis indicated that the abundance of nitrifying bacteria, especially ammonia-oxidizing bacteria, was highly decreased after long-term exposure to 50 mg/L TiO(2) NPs, which was the main reason for the serious deterioration of ammonia oxidation. Further study revealed that 50 mg/L TiO(2) NPs inhibited the activities of ammonia monooxygenase and nitrite oxidoreductase after long-term exposure, but had no significant impacts on the activities of exopolyphosphatase and polyphosphate kinase, and the transformations of intracellular polyhydroxyalkanoates and glycogen, which were consistent with the observed influences of TiO(2) NPs on biological nitrogen and phosphorus removal.     

Effects of ZnO nanoparticles on wastewater biological nitrogen and phosphorus removal

With the increasing utilization of nanomaterials, zinc oxide nanoparticles (ZnO NPs) have been reported to induce adverse effects on human health and aquatic organisms. However, the potential impacts of ZnO NPs on wastewater nitrogen and phosphorus removal with an activated sludge process are unknown. In this paper, short-term exposure experiments were conducted to determine whether ZnO NPs caused adverse impacts on biological nitrogen and phosphorus removal in the unacclimated anaerobic-low dissolved oxygen sequencing batch reactor. Compared with the absence of ZnO NPs, the presence of 10 and 50 mg/L of ZnO NPs decreased total nitrogen removal efficiencies from 81.5% to 75.6% and 70.8%, respectively. The corresponding effluent phosphorus concentrations increased from nondetectable to 10.3 and 16.5 mg/L, respectively, which were higher than the influent phosphorus (9.8 mg/L), suggesting that higher concentration of ZnO NPs induced the loss of normal phosphorus removal. It was found that the inhibition of nitrogen and phosphorus removal induced by higher concentrations of ZnO NPs was due to the release of zinc ions from ZnO NPs dissolution and increase of reactive oxygen species (ROS) production, which caused inhibitory effect on polyphosphate-accumulating organisms and decreased nitrate reductase, exopolyphosphatase, and polyphosphate kinase activities.     

Reduction of N2O and NO generation in anaerobic-aerobic (low dissolved oxygen) biological wastewater treatment process by using sludge alkaline fermentation liquid

This paper reported an efficient method to significantly reduce nitrous oxide (N(2)O) and nitric oxide (NO) generation in anaerobic-aerobic (low dissolved oxygen) processes. It was found that by the use of waste-activated sludge alkaline fermentation liquid as the synthetic wastewater-carbon source, compared with the commonly used carbon source in the literature (e.g., acetic acid), the generation of N(2)O and NO was reduced by 68.7% and 50.0%, respectively, but the removal efficiencies of total phosphorus (TP) and total nitrogen (TN) were improved. Both N(2)O and NO were produced in the low dissolved oxygen (DO) stage, and the use of sludge fermentation liquid greatly reduced their generation from the denitrification. The presences of Cu(2+) and propionic acid in fermentation liquid were observed to play an important role in the reduction of N(2)O and NO generation. The analysis of the activities of denitrifying enzymes suggested that sludge fermentation liquid caused the significant decrease of both nitrite reductase activity to NO reductase activity ratio and NO reductase activity to N(2)O reductase activity ratio, which resulted in the lower generation of NO and N(2)O. Fluorescence in situ hybridization analysis indicated that the number of glycogen accumulating bacteria, which was reported to be relevant to nitrous oxide generation, in sludge fermentation liquid reactor was much lower than that in acetic acid reactor. The quantitative detection of the nosZ gene, encoding nitrous oxide reductase, showed that the use of fermentation liquid increased the number of bacteria capable of reducing N(2)O to N(2). The feasibility of using sludge fermentation liquid to reduce NO and N(2)O generation in an anaerobic-low DO process was finally confirmed for a municipal wastewater.     

利用薯蓣皂素生产废水发酵生产s-腺苷蛋氨酸的初步研究

通过采用传统的硫酸水解工艺制得皂素废水,然后采用3种不同方式对废水进行预处理,实现了利用废水发酵生产s-腺苷蛋氨酸,同时降低废水COD值的目的。实验表明:3种不同的预处理方式对s-腺苷蛋氨酸的产量影响不同,将纯糖液的s-腺苷蛋氨酸产率记作100%,处理1,只调节废水pH发酵得到的s-腺苷蛋氨酸产量为7.75171g/L,达到纯糖液发酵的12.37%,同时废水COD去除率达35.11%;处理2,先调节废水pH然后进行活性炭吸附之后发酵得到s-腺苷蛋氨酸产量为4.29515g/L,达到纯糖液发酵的6.86%,同时废水COD去除率达71.68%;处理3,先进行活性炭吸附然后调节其pH之后发酵得到的s-腺苷蛋氨酸的产量为10.21076g/L,达到纯糖液发酵的16.30%,同时废水COD的去除率达到65.74%。从工业生产成本的角度出发,处理3的方式为最佳方式。研究实现了废水中有用资源的再利用,产生了明显的经济效益和环境效益,为工业化生产提供了理论支撑。目前该项研究在国内外未见报道。     

Enhanced microbial adaptation to p-nitrophenol using activated sludge retained in porous carrier particles and simultaneous removal of nitrite released from degradation of p-nitrophenol

In order to examine the microbial degradation of p-nitrophenol (PNP) by a mixed culture system and simultaneous removal of nitrite released via the degradation, an activated sludge retained in porous carrier particles and a suspension culture as a control were acclimated to artificial sewage containing PNP as the sole carbon source. The adaptation of microbes retained in porous carrier particles to PNP was faster than that of suspended microbes by more than 20 d. After microbial adaptation to PNP, it was degraded completely without significant accumulation of intermediate metabolites. The PNP degradation activity of the retained microbes was more than 2 times higher than that of the suspended microbes. By increasing the retained microbial concentration, nitrite released from the degraded PNP was removed by denitrification. This research demonstrates that using microbes retained in porous carrier particles is not only effective for reduction of acclimation time but also enables simultaneous removal of the nitrogen compounds resulting from the degradation of nitroaromatics.     

Denitrifying polyphosphate accumulating organisms population and nitrite reductase gene diversity shift in a DEPHANOX-type activated sludge system fed with municipal wastewater

Enhanced biological phosphorus removal (EBPR) is a widely applied method for nutrients removal, although little is known about the key genes regulating the complex biochemical transformations occurring in activated sludge during phosphorus removal. In the present study, the nitrite reductase gene (nirS) diversity and the denitrifying polyphosphate accumulating organisms (DPAOs) population, grown in a bench scale, two-sludge, continuous flow plant, operating for biological anoxic phosphorus removal (DEPHANOX-type), fed with municipal wastewater, were examined by means of physicochemical analyses and the application of molecular techniques. The DEPHANOX configuration highly influenced biomass phosphorus as well as polyhydroxyalkanoates content and facilitated the enrichment of the DPAOs population. The application of double probe fluorescent in situ hybridization (double probe FISH) technique revealed that DPAOs comprised 20% of the total bacterial population. Based on clone libraries construction and nirS gene sequencing analysis, a pronounced shift in denitrifying bacteria diversity was identified during activated sludge acclimatization. Moreover, nirS gene sequences distinct from those detected in any known bacterial strain or environmental clone were identified. This is the first report studying the microbial properties of activated sludge in a DEPHANOX-type system using molecular techniques.     

Diagnosis and quantification of glycerol assimilating denitrifying bacteria in an integrated fixed-film activated sludge reactor via 13C DNA stable-isotope probing

Glycerol, a byproduct of biodiesel and oleo-chemical manufacturing operations, represents an attractive alternate to methanol as a carbon and electron donor for enhanced denitrification. However, unlike methanol, little is known about the diversity and activity of glycerol assimilating bacteria in activated sludge. In this study, the microbial ecology of glycerol assimilating denitrifying bacteria in a sequencing batch integrated fixed film activated sludge (SB-IFAS) reactor was investigated using (13)C-DNA stable isotope probing (SIP). During steady state SB-IFAS reactor operation, near complete nitrate removal (92.7 ± 5.8%) was achieved. Based on (13)C DNA clone libraries obtained after 360 days of SB-IFAS reactor operation, bacteria related to Comamonas spp. and Diaphorobacter spp. dominated in the suspended phase communities. (13)C assimilating members in the biofilm community were phylogenetically more diverse and were related to Comamonas spp., Bradyrhizobium spp., and Tessaracoccus spp. Possibly owing to greater substrate availability in the suspended phase, the glycerol-assimilating denitrifying populations (quantified by real-time PCR) were more abundant therein than in the biofilm phase. The biomass in the suspended phase also had a higher specific denitrification rate than the biofilm phase (p = 4.33e-4), and contributed to 69.7 ± 4.5% of the overall N-removal on a mass basis. The kinetics of glycerol based denitrification by suspended phase biomass were approximately 3 times higher than with methanol. Previously identified methanol assimilating denitrifying bacteria were not associated with glycerol assimilation, thereby suggesting limited cross-utilization of these two substrates for denitrification in the system tested.     

菌酶协同改善花生粕的饲用品质

花生粕是重要的蛋白饲料原料,但由于其氨基酸不平衡,特别是精氨酸与赖氨酸比例严重失衡（精氨酸与赖氨酸含量比值在3~4,理想的精氨酸与赖氨酸含量比值为1.0）,限制了其在动物养殖中的应用。研究了复合酶预处理结合乳酸菌发酵花生粕对其品质的改善。结果表明：经菌酶协同处理后,花生粕粗蛋白质含量由46.4%提高至506%,大分子蛋白明显降解为小分子蛋白,酸溶蛋白质含量由2.3%提高至17.8%,多肽含量由1.6%提高至15.7%,蛋氨酸和赖氨酸含量分别提高了77.1%和42.0%,精氨酸降解率为18.7%,精氨酸与赖氨酸含量比值从3.7降低至2.1,总酸含量由06%提高到4.7%,其中乳酸含量由0.64 mg/g提高至14.63 mg/g。菌酶协同处理后的花生粕抗氧化性明显增强,其中每克菌酶协同处理后的花生粕对羟自由基的清除能力与171.6 mg VC相当,比花生粕（与47.6 mg VC相当）提高了2.6倍。     

黄参粗多糖脱蛋白工艺以及对亚硝酸盐清除作用的研究

采用Sevag法、TCA-Sevag法、木瓜蛋白酶-Sevag法对黄参粗多糖脱蛋白工艺进行了研究。另外,研究了体外模拟胃液条件下黄参多糖对亚硝酸盐的清除作用,采用分光光度法测定了黄参粗多糖对亚硝酸盐的清除率。实验结果表明,通过比较三种脱蛋白方法,木瓜蛋白酶-Sevag法较好,累计蛋白去除率可达68.65%,累计多糖损失率17.14%。黄参多糖对亚硝酸盐清除最佳方法为:向25mL模拟胃液中加入50mg黄参多糖,反应时间为15min,对亚硝酸盐的清除率最高,可达86.6%。     

应用A型发酵剂改善食醋风味提高出醋率

应用万家兴A型发酵剂代替麸曲、大曲和糖化酶、干酵母，与使用大曲相比，醋的风味更好，出醋率提高26．19％，食醋的原料成本降低36．36％，糖化发酵剂的成本降低82．24％；与使用麸曲相比，醋的品质大幅提高，出醋率提高28．36％，醋的成本降低26．32％，糖化发酵剂的成本降低73．52％。     

玉米液态发酵制红曲色素及在食品防腐中应用研究

以玉米粉为原料,选用红曲霉菌M3428,进行液态发酵制备红曲色素。采用正交实验设计,得出产红曲色素最佳发酵条件为:500 mL的三角瓶装液量100 mL;摇床转数150 r/min;发酵时间14天;培养基初始pH 4.5。将液态发酵得到红曲色素应用于辣白菜和熟五花肉的防腐中,结果表明:红曲色素对两种食品均具有防腐作用,用浓度25.6 mg/mL的红曲色素溶液浸泡,熟五花肉可延长保存期2天,辣白菜可延长保存期4天。     

Using video microscopy to improve quantitative estimates of protozoal motility and cell volume

The objective of this study was to apply digital imaging to improve quantification of rumen protozoal biomass and distinguish treatment differences in cell motility and volume among ruminal protozoa. Observations of protozoa in rumen fluid treated with essential oils (CinnaGar, CIN; Provimi North America, Brookville, OH) or an ionophore (monensin, MON) indicated possible cell shrinkage. We hypothesized that MON would decrease protozoal motility and interact with CIN on cell volume. In addition, we hypothesized that analysis of still frames from video of swimming protozoa would improve volume prediction accuracy. Flocculated rumen fluid was incubated in batch culture dosed with N-free feed only (control), MON, CIN, or a combination of MON+CIN. Samples were taken at 0, 3, or 6 h post-treatment and wet-mounted on a microscope fitted with a high-definition camera. At 3 h post-inoculation, there was a treatment interaction for average speed such that CIN attenuated the effect of MON, with treatment means of 243, 138, 211, and 183 µm/s for control, MON, CIN, and MON+CIN, respectively. At 6 h post-inoculation, MON decreased average speed by 79.2 µm/s compared with the main effect mean without MON. We measured both minimum and maximum diameters (depth and width, respectively) perpendicular to the longitudinal axis of swimming protozoa, yielding a 3-dimensional estimate of protozoal volume. The ellipsoid formula $\left(4/3\right)\pi abc,$ where a = 1/2 length, b = 1/2 width, and c = 1/2 depth, was compared with previously published volume estimations using genera-specific coefficients (genera-specific coefficient × length × width²). Residuals (genera-specific coefficients – ellipsoid) were plotted against predicted (ellipsoid) and centered to the mean $\left({\text{X}}_{\text{i}}-\overline{x}\right)$ to evaluate both mean and slope biases. For Entodinium spp., Y = 0.248 (±0.037) (X_i ? 7.98 × 10⁴) + 1.97 × 10⁴ (±1.48 × 10³); n = 100; r² [coefficient of determination (squared correlation coefficient)] = 0.31, with significant slope and mean biases. For family Isotrichidae, Y = ?0.124 (±0.068) (X_i ? 2.54 × 10⁶) ? 1.21 × 10⁴ (±4.86 × 10⁴); n = 32; r² = 0.10, where slope tended to be different from zero but with no mean bias. For Epidinium spp., Y = 0.375 (±0.056) (X_i ? 2.45 × 10⁵) + 6.65 × 10⁴ (±0.28 × 10⁴); n = 64; r² = 0.43, with both mean and slope biases. The present regression analyses demonstrate that the genera-specific coefficient-based method more likely overestimates volume for Entodinium and Epidinium than for the teardrop-shaped Isotrichidae. Based on simulations derived from previous literature reporting treatments that depress protozoal populations or among-animal changes in protozoal population structures, our proposed ellipsoid method offers potential to advance the prediction of treatment effects on protozoal volume and to shift focus from the number of cells present to the diversity, function, and biomass of protozoa under various treatment conditions.     

Nitrogen removal characteristics and biofilm analysis of a membrane-aerated biofilm reactor applicable to high-strength nitrogenous wastewater treatment

A membrane-aerated biofilm reactor (MABR) capable of simultaneous nitrification and denitrification in a single reactor vessel was developed to investigate the characteristics of nitrogen removal from high-strength nitrogenous wastewater, and biofilm analysis using microelectrodes and the fluorescence in situ hybridization (FISH) technique was performed. Mean removal percentages of total organic carbon (TOC) and nitrogen were 96% and 83% at removal rates of 5.76 g-C m(-2) d(-1) and 4.48 g-N m(-2) d(-1), respectively. For stable removal efficiency, constant washing of the biofilm was needed. Dissolved oxygen microelectrode measurement revealed that the biofilm thickness was about 1600 microm, and that oxygen penetrated about 300 to 700 microm, from the outer surface of the membrane. Furthermore, FISH analysis revealed that ammonia-oxidizing bacteria (AOB) were located near the outer surface of the membrane, whereas other bacteria were located from the inner to the outer part of the biofilm. Combining these results demonstrated that simultaneous nitrification and denitrification occurred in the biofilm of the MABR system. In addition, stoichiometric analysis revealed that after 130 d(-1), the free ammonia (FA) concentration ranged within the concentration causing inhibition of the growth of nitrite oxidizing bacteria (NOB) and that AOB consumed 86% of the oxygen supplied through the intra-membrane. These results indicate that nitrogen removal not via nitrate but via nitrite was mainly achieved in the MABR system.     

牛干巴中降胆固醇、降亚硝酸盐乳酸菌的分离筛选及其发酵性能

以传统发酵牛干巴作为乳酸菌筛选源,分离出18株乳酸菌,通过OPA法测定降胆固醇能力,盐酸萘乙二胺比色法测定降解亚硝酸盐能力,菌株NR7对胆固醇的清除率是22.61%,培养12 h和24 h亚硝酸盐分别降解了34.177μg/m L和95.82μg/m L,在p H3.0的环境中活菌率达99.50%,对0.3%的胆盐耐受性强。因此,选择NR7作为目的菌株,进一步研究其生产适应性,能够在发酵4 h后使p H迅速降低,能够在15⁴0℃环境条件下生长,能够耐受8%的Na Cl和200 mg/kg的Na NO₂,且真空冷冻干燥后活菌率93.62%,4℃条件下保藏30 d后活菌率可达89.99%。16S rRNA分子生物学鉴定,菌株NR7为植物乳杆菌。      

Potential of lactic acid bacteria to improve the fermentation and quality of coffee during on‐farm processing

This study describes, for the first time, the potential use of selected lactic acid bacteria (LAB) to conduct improved coffee bean fermentation during on‐farm wet processing. Among different strains tested, Lactobacillus plantarum LPBR01 showed a suitable production of organic acids and flavour‐active esters in a coffee‐pulp simulation medium and was used as starter culture under field conditions. The results indicated that L. plantarum LPBR01 was able to establish an accelerated coffee‐pulp acidification process and potentially reduced the fermentation time from 24 to 12 h. The inoculation of LPBR01 strain also increased significantly the formation of volatile aroma compounds during fermentation process (such as ethyl acetate, ethyl isobutyrate and acetaldehyde) and enabled the production of beverage with distinct sensory notes and a remarkable increase in quality compared to the conventional process. Our results suggest that the use of LAB in coffee processing is an ideal alternative way to conduct faster and improved coffee bean fermentation.