Dewatering of Brewery Sludge Produced from a Dedicated Aerobic Effluent Treatment Plant

This paper details the characterisation of sludge produced from a trickling filter effluent treatment plant dedicated to the treatment of brewery effluent and reports on centrifuge trials for thickening and dewatering it. Characterisation of the sludge revealed that the total solids content was low and variable, at 2 — 2.5% w/w dried solids (DS), and that the sludge exhibited very poor settling characteristics. A study of the rheological properties of the sludge indicated that at around 2.5% w/w DS the sludge could best be modelled by the Hershel-Bulkley equation. The variation in rheological properties with solids concentration was measured on samples thickened in the laboratory. Large scale dewatering of polyelectrolyte conditioned sludge was carried out using an Alfa Laval decanter centrifuge in order to obtain cake suitable for further processing or disposal. Operational and dosing conditions were varied and a cake with up to 25% w/w DS was produced using cationic polyelectrolytes Zetag-87 & CT85.     

Enhanced treatment efficiency of an anaerobic sequencing batch reactor (ASBR) for cassava stillage with high solids content

Cassava stillage is a high strength organic wastewater with high suspended solids (SS) content. The efficiency of cassava stillage treatment using an anaerobic sequencing batch reactor (ASBR) was significantly enhanced by discharging settled sludge to maintain a lower sludge concentration (about 30 g/L) in the reactor. Three hydraulic retention times (HRTs), namely 10 d, 7.5 d, 5 d, were evaluated at this condition. The study demonstrated that at an HRT of 5 d and an organic loading rate (OLR) of 11.3 kg COD/(m³ d), the total chemical oxygen demand (TCOD) and soluble COD (SCOD) removal efficiency can still be maintained at above 80%. The settleability of digested cassava stillage was improved significantly, and thus only a small amount of settled sludge needed to be discharged to maintain the sludge concentration in the reactor. Furthermore, the performance of ASBR operated at low and high sludge concentration (about 79.5 g/L without sludge discharged) was evaluated at an HRT of 5 d. The TCOD removal efficiency and SS in the effluent were 61% and 21.9 g/L respectively at high sludge concentration, while the values were 85.1% and 2.4 g/L at low sludge concentration. Therefore, low sludge concentration is recommended for ASBR treating cassava stillage at an HRT 5 d due to lower TCOD and SS in the effluent, which could facilitate post-treatment.     

中试规模厌氧序批式反应器的工艺特性

采用有效容积为100L的中试规模厌氧序批式反应器(ASBR)处理合成废水,研究进水时间、搅拌、有机负荷等因素对反应器运行效果的影响,并对反应器的抗冲击性能进行了考察.结果表明,进水时间和搅拌是影响反应器运行效果的两个重要因素.高负荷运行时进水时间越短,系统对废水的化学需氧量(COD)去除率越低;适当地搅拌可以缩短反应时间,提高系统的处理能力;有机负荷的提高有利于废水化学需氧量的去除;进水pH值和温度突然变化并没有对反应器的运行产生很大的影响,中试规模ASBR反应器具有很强的抗冲击性能力.     

Stimulation of anaerobic digestion of thickened sewage sludge by iron-rich sludge produced by the fenton method

In batch mesophilic anaerobic digestion of a mixture of iron-rich sludge collected from Fenton treatment of molasses wastewater (MWW) and thickened sewage sludge from a municipal wastewater treatment plant, the methane content in the gas from the mixture was significantly higher than that from thickened sewage sludge only. When minerals in iron-rich sludge obtained by incineration were fed to thickened sewage sludge in semi-continuous experiments, the methane content obtained by digestion of thickened sewage sludge only increased approximately from 53% to 64%. These results suggest that iron-rich sludge can enhance methane production for thickened sewage sludge.     

Determination of Particle Density and Porosity in Foods and Porous Materials with High Moisture Content

A simple gas pycnometer was developed to obtain the volume of porous food materials. The volume is obtained by measuring the change in pressure experienced by an amount of compressed gas filling a constant volume reference chamber when it expands into a second chamber containing a sample of the material to be tested. From such pressure change and the knowledge of the volumes of the two chambers the volume of the sample solid matrix is determined. The main difference between the proposed pycnometer and the typical helium pycnometer is the sequence of chambers; in the latter gas compression is made in the sample chamber, producing evaporation of water and volatiles when the gas is expanded into the reference chamber. For these reasons the helium pycnometer is only recommended for volume measurements of bone dry solids. The performance of the gas pycnometer was assessed by measuring the volume of different solids (non-porous metallic cylinder, glass spheres, porous metallic cylinder, sintered sand cylinder and apples) and by comparing the results with values from other methods. The gas pycnometer reproducibility of 0.019%, obtained with dried porous materials, is excellent when compared with a commercial helium pycnometer. The gas pycnometer proposed in this work can be easily built and offers reliable results of particle volume for any type of solids, specifically foods and other materials with high moisture content.     

Effect of mixing method on resulting thickness of infant formula

Previous research shows that factors such as time, temperature, nutritional make‐up of a liquid, and type of thickening agent can significantly alter the resulting thickness of liquids. This study sought to determine the effect of three distinct mixing methods on the resulting thickness of ready to feed infant formulas mixed to Mildly and Moderately Thick (International Dysphagia Diet Standardization Initiative [IDDSI] Levels 2 and 3) with three different thickening agents. Eight commercially available infant formulas were mixed with three different thickening agents by three different mixing methods. The IDDSI Syringe Flow Test was used to categorize the thickened formulas. Chi square analyses were completed to determine the impact of mixing method on the thickened formulas. The majority (94%) of thickened formula combinations prepared to a target Mildly Thick consistency produced thickened formula that was thinner or thicker than the target. In contrast, the majority (76%) of thickened formula combinations prepared to a target Moderately Thick (IDDSI Level 3) consistency produced thickened formula that was equivalent to the target consistency. A statistically significant relationship was found between mixing methods and resulting IDDSI category for samples mixed to a target of Moderately Thick. The thickening agent and method of mixing must be considered carefully when preparing infant formulas to Mildly and Moderately Thick target IDDSI categories. Based on results of this study, it is recommended that providers utilize a clinical testing method, such as the IDDSI Syringe Flow Test, when attempting to create a Mildly Thick formula consistency.     

透明质酸多糖增稠适用于吞咽困难的肠内营养制剂及其流变学性质

胶体增稠的食物流体黏度是吞咽困难饮食护理中的关键参数。这类流体需有较高的黏度和较强的非牛顿流体行为。本研究采用流变学方法表征了透明质酸多糖对含豌豆蛋白和大豆油的营养制剂的增稠效果,研究了增稠营养制剂的流动性质、黏弹性和黏度的剪切时间依赖性。结果表明：未经增稠的营养制剂是表观黏度很低（仅约为0.010 Pa·s）的牛顿流体,不能满足安全吞咽的要求;而透明质酸具有良好的增稠效果,当透明质酸质量分数为0.5%时,营养制剂的初始黏度可达8 Pa·s,增稠后营养制剂具有方便可调节的表观黏度、剪切变稀性质以及良好的黏弹性,流变学性质能满足安全吞咽的要求。     

A new process for efficiently producing methane from waste activated sludge: alkaline pretreatment of sludge followed by treatment of fermentation liquid in an EGSB reactor

In the literature the production of methane from waste activated sludge (WAS) was usually conducted in a continuous stirred tank reactor (CSTR) after sludge was pretreated. It was reported in our previous publication that compared with other pretreatment methods the methane production in CSTR could be significantly enhanced when sludge was pretreated by NaOH at pH 10 for 8 days. In order to further improve methane production, this study reported a new process for efficiently producing methane from sludge, that is, sludge was fermented at pH 10 for 8 days, which was adjusted by Ca(OH)(2), and then the fermentation liquid was treated in an expanded granular sludge bed (EGSB) for methane generation. First, for comparing the methane production observed in this study with that reported in the literature, the conventional operational model was applied to produce methane from the pH 10 pretreated sludge, that is, directly using the pH 10 pretreated sludge to produce methane in a CSTR. It was observed that the maximal methane production was only 0.61 m(3)CH(4)/m(3)-reactor/day. Then, the use of fermentation liquid of pH 10 pretreated sludge to produce methane in the reactors of up-flow anaerobic sludge bed (UASB), anaerobic sequencing batch reactor (ASBR) and EGSB was compared. The maximal methane production in UASB, ASBR, and EGSB reached 1.41, 3.01, and 12.43 m(3)CH(4)/m(3)-reactor/day, respectively. Finally, the mechanisms for EGSB exhibiting remarkably higher methane production were investigated by enzyme, adenosine-triphosphate (ATP), scanning electron microscope (SEM) and fluorescence in situ hybridization (FISH) analyses. It was found that the granular sludge in EGSB had the highest conversion efficiency of acetic acid to methane, and the greatest activity of hydrolysis and acidification enzymes and general physiology with much more Methanosarcinaceae.     

Floc volume effects in suspensions and its relevance for wastewater engineering

The aim of this paper is to better understand oxygen transfer reduction caused by floc suspensions. We demonstrate that the overall floc volume significantly influences oxygen transfer depletion. Submerged fine bubble and coarse bubble diffusers are affected in the same way by this phenomenon. The mixed liquor suspended solids concentration (MLSS concentration) is not an appropriate parameter for describing or relating phenomena that are caused by the overall floc volume in activated sludge (e.g., oxygen transfer depression and sludge sedimentation characteristics). A better correlation is achieved by using the mixed liquor volatile suspended solids concentration (MLVSS concentration). To characterize the effects of the overall floc volume in suspensions whose MLVSS concentration cannot be determined (e.g., inorganic iron hydroxide flocs), a new method-the hydrostatic floc volume (HFV)-that approximates the overall floc volume in floc suspensions is introduced. Application of this method demonstrates that oxygen transfer depression caused by iron hydroxide flocs and activated sludge flocs is similar.     

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.     

Comparison performances of membrane bioreactor and conventional activated sludge prcesses on sludge reduction induced by Oligochaete

Pilot-scale experiments were carried out to compare sludge reduction induced by Oligochaete in a submerged membrane bioreactor (MBR) and a conventional activated sludge (CAS) reactor for 345 d. Worm growth in the CAS reactor was much better than in the MBR. The average worm density of the aeration tank in the CAS reactor was 71 total worms/mg of volatile suspended solids (VSS), much higher than that in the MBR (10 total worms/mg of VSS). Worms did not naturally produce in the MBR, and the dominant worm type in the MBR depended on sludge inoculation from the CAS reactor. Only two types of worms were found in the MBR, Aeolosoma hemprichicii and Nais elinguis. Worm presence and disappearance in the MBR alternated. Worms in the CAS reactor occurred nearly throughout the operating period and were continuously maintained at over 30 total worms/mg of VSS in the aeration tank for 172 d. Three types of worm were found in the CAS reactor, A. hemprichicii, Pristina aequiseta, and N. elinguis, but P. aequiseta was present only occasionally. The alternating dominance of worm types in both reactors changed between Aeolosoma and Nais, and the time of Aeolosoma dominance was longer than that of Nais dominance. Worm growth in the MBR contributed to neither sludge reduction nor improvement of sludge settling characteristics because of low density. But worm presence and bloom in the CAS reactor greatly decreased sludge yield and improved sludge settling characteristics at high density. Both the average sludge yield (0.17 kg of suspended solids (SS)/kg of chemical oxygen demand removed (CODremoved)) and sludge volume index (60 mL/g) in the CAS reactor were much lower than those in the MBR (0.40 kg of SS/kg of CODremoved and 133 mL/g). Nais had more potential for sludge reduction than Aeolosoma. Worm growth had little impact on effluent quality in the MBR but affected effluent quality very much in the CAS reactor.     

Formation and characterization of aerobic granules in a sequencing batch reactor treating soybean-processing wastewater

Aerobic granules were cultivated in a sequencing batch reactor (SBR) fed with soybean-processing wastewater at 25+/-1 degrees C and pH 7.0+/-0.1. The granulation process was described via measuring the increase of sludge size. The formation of granules was found to be a four-phase process, that is, acclimating, shaping, developing, and maturated. A modified Logistic model could well fit with the granule growth by diameter and could be employed to estimate the maximum diameter, lag time, and specific diameter growth rate effectively. Both normal and log-normal distributions proved to be applicable to model the diameter distribution of the granules. The granule-containing liquor was shear thinning, and their rheological characteristics could be described by using the Herschel-Buckley equation. The suspended solids concentration, pH, temperature, diameter, settling velocity, specific gravity, and sludge volume index all had an effect on the apparent viscosity of the mixed liquor of granules. The matured granules had fractal nature with a fractal dimension of 1.87+/-0.34. Moreover, 83% of matured granules were permeable with fluid collection efficiencies over 0.034. As compared to activated sludge flocs, the aerobic granules grown on the soybean-processing wastewater had better settling ability, mass transfer efficiency, and bioactivity.     

Ferrate treatment for removing chromium from high-level radioactive tank waste

A method has been developed for removing chromium from alkaline high-level radioactive tank waste. Removing chromium from these wastes is critical in reducing the volume of waste requiring expensive immobilization and deep geologic disposition. The method developed is based on the oxidation of insoluble chromium(III) compounds to soluble chromate using ferrate. This method could be generally applicable to removing chromium from chromium-contaminated solids, when coupled with a subsequent reduction of the separated chromate back to chromium(III). The tests conducted with a simulated Hanford tank sludge indicate that the chromium removal with ferrate is more efficient at 5 M NaOH than at 3 M NaOH. Chromium removal increases with increasing Fe(VI)/Cr(II) molar ratio, but the chromium removal tends to level out for Fe(VI)/ Cr(III) greaterthan 10. Increasingtemperature leadsto better chromium removal, but higher temperatures also led to more rapid ferrate decomposition. Tests with radioactive Hanford tank waste generally confirmed the simulant results. In all cases examined, ferrate enhanced the chromium removal, with a typical removal of around 60-70% of the total chromium present in the washed sludge solids. The ferrate leachate solutions did not contain significant concentrations of transuranic elements, so these solutions could be disposed as low-activity waste.     

Anaerobic granular reactors for the treatment of dairy wastewater: A review

Considerable research has been conducted on the treatment of dairy wastewater by anaerobic granular reactors. Upflow anaerobic sludge blanket (UASB) reactors, anaerobic sequencing batch reactors (ASBR) and static granular bed reactors (SGBR) are the conventional granular reactor types most commonly applied in dairy wastewater treatment. Hybrid systems have also been developed to increase treatment efficiency and overcome the operational problems associated with the treatment of this substrate. Effects of parameters including temperature, organic loading and operating protocols on the performance of granular reactors are summarised. Individual and hybrid granular reactors are evaluated based on organic matter removal and methane production capacity.     

Influence of different mesh filter module configurations on effluent quality and long-term filtration performance

Recently, a new type of wastewater treatment system became the focus of scientific research: the mesh filter activated sludge system. It is a modification of the membrane bioreactor (MBR), in which a membrane filtration process serves for sludge separation. The main difference is that a mesh filter is used instead of the membrane. The effluent is not of the same excellent quality as with membrane bioreactors due to the much lager pore sizes of the mesh. Nevertheless, it still resembles the quality of currently used standard treatment system, the activated sludge process. The new process shows high future potential as an alternative where a small footprint of these plants is required (3 times lower footprint than conventional activated sludge systems because of neglecting the secondary clarifier and reducing the biological stage). However, so far only limited information on this innovative process is available. In this study, the effect of different pore sizes and different mesh module configurations on the effluent quality was investigated varying the parameters cross-flow velocity (CFV) and flux rate. Furthermore the long-term filtration performance was studied in a pilot reactor system and results were compared to the full-scale conventional activated sludge process established at the same site. The results demonstrate that the configuration of the filter module has little impact on effluent quality and is only of importance with regard to engineering aspects. Most important for a successful operation are the hydrodynamic conditions within the filter module. The statement "the higher the pore size the higher the effluent turbidity" was verified. Excellent effluent quality with suspended solids between 5 and 15 mg L(-1) and high biological elimination rates (chemical oxygen demand (COD) 90-95%, biological oxygen demand (BOD5) 94-98%, total nitrogen (TN) 70-80%, and ammonium nitrogen (NH(4)-N) 95-99%) were achieved and also compared to those of conventional activated sludge systems. Regarding the air requirement for module aeration, which is the main cost factor in MBR technology, an astonishing optimization could be achieved. During the long-term filtration experiments only 4 N m(3)/m(3) was necessary to keep a stable filtration process for more than 3 weeks (MBR 20-50 N m(3)/m(3)).     

改善造纸污泥脱水性条件对CST的影响

研究了改善造纸污泥脱水性条件对毛细管吸水时间（CST）的影响,结果表明,先进行300 r/min、10 min的急速搅拌,再进行50 r/min、15 min缓慢搅拌时,造纸污泥的脱水性最佳。提高废水温度,废水黏度降低,CST值也逐渐减小;pH值约为7时,CST值最低,说明中性条件可改善造纸污泥的脱水性能;高分子絮凝剂对CST值的影响表明,阳离子聚丙烯酰胺（CPAM）对提高造纸污泥脱水性优于阴离子聚丙烯酰胺（APAM）。     

Gravity flow test comparisons for mildly thick consistency

Simple measurement tools that provide objective information about the consistency of thickened liquids have received increasing attention given possible application to clinical practice for dysphagia. The International Dysphagia Diet Standardization Initiative (IDDSI) advocates the use of the IDDSI Flow Test for measuring thickness and verifying a prescribed level of consistency. This study compares gravity flow test measurements taken with two 10-ml syringes of starch and gum-thickened samples prepared to a mildly thick consistency using product label information. One of the 10-ml syringes met IDDSI specification and the other 10-ml syringe did not. Thickened samples also were measured using the line spread apparatus. The results showed that two syringes yielded significantly different gravity flow test measurements, often resulting in changes to the classification level of thickness. There was no effect of thickening agent. Line spread measurements did not vary from one another. Study findings indicate the importance of continued testing with the IDDSI Flow Test and education/awareness about the use of the IDDSI reference syringe. An essential aspect about the use of thickened liquids in dysphagia management is that beverage preparations represent their prescribed level of modification. The findings of this study indicate the importance of following syringe specifications when conducting gravity flow testing using the IDDSI methodology. The implication is that the wrong 10-ml syringe could result in errant clinical decisions in determining the accuracy of texture modifications, resulting in care providers who are more likely to over or under thicken modifications to achieve a targeted level of thickness.     

Occurrence and solid-liquid partition of sulfonated naphthalene-formaldehyde condensates in the aquatic environment

Sulfonated naphthalene-formaldehyde condensates (SNFC) are high production volume chemicals used in a variety of applications, for example, as concrete plasticizers, tanning agents, or dye dispersants. They enter the aquatic environment primarily by the wastewater path. The occurrence and fate of the monomers, which are different isomers of mono- and disulfonated naphthalene, was intensively investigated in previous studies. However, the environmental fate of the persistent higher molecular SNFC is so far widely unknown. This paper describes an ultrasonic extraction under alkaline conditions, followed by ion-pair HPLC with fluorescence detection for the analysis of SNFC oligomers from solid environmental matrixes such as sewage sludge, suspended solids, and river sediments. Limits of quantification of about 0.1 mg kg-1 d.m. were well below the measured concentrations in environmental samples. SNFC were adsorbed to suspended solids and river sediments in three major German rivers (Rhine, Neckar, and Danube) in concentrations typically up to several mg kg(-1) d.m. A total content of about 4 g kg(-1) d.m. was measured in a sewage sludge of a municipal wastewater treatment plant, which receives wastewater from a textile dyeing plant. Furthermore, the first quantitative field data on the partition of SNFC and their monomers between the aqueous phase and solid environmental compartments are presented. Solid-liquid partition coefficients (Kd) of oligomers with a chain-length ranging from three to six naphthalenesulfonate units were derived from the analysis of corresponding wastewater and sewage sludge samples and from suspended solids and river water samples, respectively. Determined Kd values were in the range from 10(2) to 10(4) L kg(-1).     

制浆造纸污泥深度脱水压榨机的研发

介绍了制浆造纸污泥深度脱水压榨机的结构、工作原理及应用,该机适用于各类废纸制浆纤维含量高的初沉污泥的浓缩处理,能将含水量95%左右的污泥压榨浓缩至含水量50%左右的成品污泥。整机采用全封闭式结构,单机浓缩效果好,效率高,成本低,大大简化了污泥浓缩工艺流程。     

应用于高温气体过滤的烧结金属过滤器

在应用于化学加工、石油炼制、石油化工和基础重工业生产的众多工业气体过滤的气固分离中,烧结金属过滤系统被证实是一种高效、可靠和经济的选择。叙述了工业应用的,特别是要求半固定过滤的在高温高压下腐蚀环境中应用的烧结金属粉末或者烧结金属纤维过滤器的优点,讨论了所选应用领域,包括流化催化裂化(FCC)和连续催化重整/脱硫(CCR)的过滤器的操作和性能。