UASB+SBR工艺处理皂素生产废水的快速启动研究

皂素生产废水为难处理高浓度酸性含硫有机废水.其中高含量的硫酸盐在厌氧条件下产生大量的H2S,造成了对厌氧微生物的抑制作用,严重影响厌氧生物处理的效果,甚至使厌氧消化完全失败,使该类废水的处理较为困难.为了有效解除硫酸盐对生物处理设施中微生物的抑制,找出皂素生产废水的快速启动运行的方法,本文选用了UASB SBR组合工艺进行了2个月左右的动态连续流实验,对硫酸盐抑制的解除方法进行了研究,提出了相应的解除硫酸抑制厌氧消化的方法,找到了UASB快速启动的有效方法.小试连续运行实验结果表明,在UASB中加入适量铁屑和活性炭颗粒,以生活污水处理厂剩余污泥为种泥可以成功实现UASB SBR处理系统的快速启动,消除DO2-4对生物处理系统的影响,并在较短的时间内(21 d左右)培养出了厌氧颗粒污泥.UASB启动后,在进水COD质量浓度34 000mg/L左右时,COD的去除率一直保持在95%以上,出水COD质量浓度维持在1 300 mg/L左右.厌氧出水经过SBR处理后,出水水质达到了<综合污水排放标准>中的二级排放标准要求.该快速启动方法可供类似酸性高浓度有机废水处理和调试参考.     

Water treatment sludge for phosphate removal from the effluent of UASB reactor treating municipal wastewater

Aluminium-based water treatment sludge was used as a coagulant for removing/recovering phosphate from the effluent of upflow anaerobic sludge blanket (UASB) reactor treating municipal wastewater. The effect of three variables, namely sludge dose, initial pH and fresh coagulant (poly-aluminium chloride, PACl) dose was studied using response surface methodology. About 87% phosphate removal could be obtained at the optimum conditions of sludge dose 13.8 g/L, initial pH 6, and fresh PACl dose 5.8 mg Al/L. In order to achieve a similar phosphate removal, a dose in the range of 30–40 mg Al/L of fresh PACl was required. The results suggest that water treatment sludge can be reused as a coagulant for post-treatment of UASB reactor effluent treating municipal wastewater and can be considered as a promising alternative for removing phosphate which can substantially reduce the consumption of fresh PACl. The sludge generated during this process could potentially be used in land application which results in recycling of phosphate.     

UASB反应器中厌氧氨氧化菌脱氮效果及运行条件

通过UASB反应器中接种厌氧氨氧化颗粒污泥,处理模拟实验废水,检测其厌氧脱氮效果,并探寻其最佳运行条件。研究表明,UASB反应器中厌氧氨氧化菌具有高效的脱氮效果。厌氧氨氧化菌对NH~+_4-N和NO~-_2-N的适宜浓度负荷均为220 mg/L,水力停留时间适宜为4 h,最适温度为35℃,最佳p H值为8.0,在此条件下,NH~+_4-N,NO~-_2-N和TN的去除率分别可达97%,98.5%及88%。     

Analysis of the chosen thermal and flammability parameters of dried sewage dust

The hazardous sludge disposal process in the form of landfills requires the determination inter alia of the flammable and explosion properties of dried sewage sludge dust, which has the ability to ignite and spontaneously combust when stored in silos. At a constant furnace surface temperature, the minimum ignition temperature of the sludge dust layer with a layer thickness of 5 mm is 270 °C, and for a layer thickness of 12.5 mm it is 250 °C. Two selected fire extinguishing powders for Class A, B, C and D fires were used in the study to determine the possibility of reducing the susceptibility of dried wastewater to ignition from heated surface, self-ignition and explosion parameters. The most effective extinguishing powder was ABC Favorit, which increased the value of the minimum ignition temperature of the layer (5 mm thick) to 360 °C and the spontaneous ignition temperature of the sludge with this powder increased by 22 °C at 169.6 cm³ in comparison to the sludge without extinguishing powder, respectively. The lowest self-ignition temperature of 136 °C was recorded for the largest tested volume (169.6 cm³) for dried sewage dust without any fire extinguishing powders. The biggest values of p_max and (dp/dt)_max dried sewage dust were recorded 4.8 bar and 113 bar/s respectively. By analysing the obtained test results, it can be assumed that dried sewage dust is a combustible material with properties similar to biomass.     

Monitoring of pathogenic microorganisms contamination during heat drying process of sewage sludge

The sewage sludge from wastewater treatment plant is a potential source of infectious organism. The number and type of pathogens in sludge depends on various factors namely, the wastewater source, the type of treatment plant, and other environmental factors such as the biological medium offered by the sewage sludge. The principal sludge-borne diseases are presented followed by discussion on biological aspect of growth and occurrence. The overall objective of this work is to estimate kinetic reduction of pathogen population in sludge during different thermal-drying process including: the agitated conductive drying, drum drying, solar drying, and fry-drying. The temperature curves were reported from literature except frying data which were determined in experiment. In order to apply the temperature influence on pathogens population, kinetic parameters for the thermal inactivation (D, z-values) were chosen from literature. Values of concentrations of each pathogen were also extracted from scientific review of pathogens in bio-solids. This study conducted to resolve the survival kinetic of Hepatitis A viruses. The result showed that a concentration of 7 × 10⁴ cfu/100 ml initially present in the sewage sludge is significantly reduced during the heat drying processes except the solar plant. The sewage sludge is completely disinfected when heated for 20 min, 10 min, and 10 s, respectively, during the agitated conductive process, vacuum fry-drying, and drum drying process.     

Emergy analysis of cassava vinasse treatment

Vinasse has great pollution to the environment. A number of technologies have been explored for reducing the pollution of vinasse. Sustainability has become an important factor when discussing wastewater treatment techniques. Emergy analysis was used to evaluate the treatment of cassava vinasse in this paper. Cr (emergy consumption ratio) as a new emergy index was proposed to measure the impact of waste treatment to the society. Centrifugal solid–liquid separation, UASB (up-flow anaerobic sludge bed), and SBR (sequencing batch reactor activated sludge process) are used in the treatment process. The emergy indices for cassava vinasse treatment system were as follows: EYR (emergy yield ratio) was 6.20, ELR (environmental loading ratio) was 5.81, ESI (emergy sustainability index) was 1.07, and Cr was 4.60E+12 sej/m³. The emergy of coal electricity accounts for 46% of all purchased inputs. It is necessary to improve the treatment technology to reduce the electricity used.     

Disintegration of waste activated sludge by different applications of Fenton process

Oxidative disintegration of municipal waste activated sludge (WAS) using conventional Fenton (Fe²⁺ + H₂O₂, CFP) and Fenton type (Fe⁰ + H₂O₂, FTP) processes was investigated and compared in terms of the efficiency of sludge disintegration and enhancement of anaerobic biodegradability. The influences of different operational variables namely sludge pH, initial concentration of Fe²⁺ or Fe⁰, and H₂O₂ were studied in detail. The optimum conditions have been found as catalyst iron dosage = 4 g/kg TS, H₂O₂ dosage = 40 g/kg TS and pH = 3 within 1 h oxidation period for both CFP and FTP. Kinetics studies were performed under optimal conditions. It was determined that the sludge disintegration was happened in two stages by both processes: rapid and subsequent slow disintegration stages and rapid sludge disintegration stage can be described by a zero-order kinetic model. The effects of oxidative sludge disintegration under the optimum conditions on anaerobic digestion were experienced with biochemical methane potential (BMP) assay in batch anaerobic reactors. Total methane production in the CFP and FTP pre-treated reactors increased by 26.9% and 38.0%, relative to the untreated reactor (digested the raw WAS). Furthermore, the total chemical oxygen demand reductions in the pre-treated reactors were improved as well.     

Experimental study of the characteristics of solid fuel from fry-dried swine excreta

Swine excreta were dried by boiling via immersion in hot oil. In this method, moisture in the excreta is replaced with oil or evaporated by turbulent heat transfer in high-temperature oil. The dried excreta can be used in an incinerator like low-rank coal or solid fuel. Refined waste oil and B–C heavy oil were used for drying. Drying for 8 min at 150 °C reduced the water content of raw excreta from 78.90 wt.% to 1.56 wt.% (refined waste oil) or 1.62 wt.% (B–C heavy oil) and that of digested excreta from 79.58 wt.% to 3.40 wt.% (refined waste oil) or 3.48 wt.% (B–C heavy oil). The low heating values of the raw and digested excreta were 422 kJ/kg and ?2,713 kJ/kg, respectively, before drying and 27,842–28,169 kJ/kg and 14,394–14,905 kJ/kg, respectively, after drying. A heavy metal analysis did not detect Hg, Pb, Cd, As, and Cr in the dried excreta, but Al, Cu, and Zn, which occur in the feed formula, were detected. Thermogravimetric analysis before and after drying revealed that emission of volatiles and combustion of volatiles and fixed carbon occurred at temperatures of 250–500 °C when air was used as the transfer gas.     

Anammox in a UASB reactor treating saline wastewater

The feasibility of an anammox (anaerobic ammonium oxidation) UASB (upflow anaerobic sludge blanket) bioreactor to treat ammonium-rich brines was investigated in batch and continuous-flow experiments. The evidence from batch tests indicated that the anammox activity was significantly inhibited under highly saline conditions while the inhibition was reversible. Saline shock loading of 30 g NaCl l⁻¹ caused a 67.5% decrease in specific anammox activity (SAA) compared to reference biomass (not exposed to salt). However, the acclimatized biomass displayed a SAA value just 45.1% lower than that of the reference biomass. When transferred from brine to freshwater, the salt-exposed biomass resumed its activity by 43.1%. Subsequent to appropriate acclimatization, careful manipulation nitrite concentration, nitrogen loading rate (NLR), and other operational parameters for 77 days, the results of continuous-flow experiment revealed that under the salinity of 30 g NaCl l⁻¹ the reactor performed well and the substrate removal capacity (nitrogen removal rate, NRR, of 448 ± 15 mgl⁻¹ d⁻¹) was comparable to the condition of freshwater (NRR of 464 ± 13 mgl⁻¹ d⁻¹). However, the anammox UASB bioreactor was prone to malfunction under transient operating conditions.     

Drop in dry mass and organic substance content in the process of autothermal thermophilic aerobic digestion

This paper presents the results of a study of a sludge subjected to the (ATAD) process – Autothermal Thermophilic Aerobic Digestion occurring in a two-stage installation operated in a municipal wastewater treatment plant in Olecko, Poland. The study of the sludge and the analysis of obtained results were conducted over 2011 and 2014. The subject of the study was a thickened sludge in an intermediate tank from which it was next transferred to facility reactors. The stabilization of processed sludge was evaluated analyzing the change in the dry mass (DS) content in the sludge. Measurements were carried out in thickened sludge samples and after the ATAD process. Collected results were then subjected to a statistical analysis and it was determined to which extent as resulted from the subject process the dry mass and the dry organic mass (VS) content was changing in the sludge. Also, it was analyzed how the oxygen chemical demand (COD) was changing. The dry mass content in the thickened sludge was from 60 g/l to 160 g/l. After the process, this amount was from 35 to 76 g/l. Similarly, the organic mass content in a dry sludge mass changed from initial values within a range of 44–135 g/l to 23–60 g/l after the ATAD process. Also, the organic substance content expressed as COD decreased from 80 to 467 g O₂/l in a thickened sludge to 51–261 g O₂/l in the sludge after the process. The article presents conclusions from the result of the conducted study as well as personal experience.     

Phosphate removal using aerobic bacterial consortium and pure cultures isolated from activated sludge

In the present study, an attempt is made to evaluate the kinetics of biological phosphate removal using a bacterial consortium of activated sludge, as well as screening for dominant polyphosphates accumulating bacteria. The results showed an efficient phosphate uptake (P < 0.001) of the consortium, with rates related to the initial concentration of both phosphate and carbon sources. Short chain volatile fatty acids presented the suitable substrates for enhanced biological phosphorus removal, of which maximum yield reached 99.23% and 78.51% in basal salt medium supplemented with 0.5% of sodium acetate and lactate respectively. Fifteen phosphate-accumulating bacteria were isolated from the activated sludge and only four isolates were selected and characterized as Pseudomonas aeruginosa AS1, Moraxella lacunata AS2, Acinetobater junii AS3 and Alcaligenes denitrificans AS4. The highest efficiency of phosphate uptake using pure culture was achieved with Ac. junii AS3 (83.36) followed by P. aeruginosa AS1 (81.78%), Al. denitrificans AS4 (76.72%), and M. lacunata AS2 with 50.6%.     

High nitrite accumulation and strengthening denitrification for old-age landfill leachate treatment using an autocontrol two-stage hybrid process

An autocontrol two-stage hybrid process was developed to treat landfill leachate. Biological nitrogen removal with nitrification and denitrification via nitrite pathway was split into two stages. The first stage was designed for the high nitrite accumulation and was composed of two hybrid bed reactors (Hybrid I and Hybrid II) and a coagulation–flocculation reactor having effective volumes of 120 L and 80 L, respectively. The second stage was designed for strengthening denitrification and included a single 80 L reactor. The carriers of the hybrid bed reactors were composed of fixed multiple flexible carriers and suspended particle carriers. Dissolved oxygen (DO), pH value, oxidation–reduction potential (ORP) and temperature were used as online fuzzy control parameters of the automatic control system. The concentration of nitrite in Hybrid I and Hybrid II could reach 411 mg L⁻¹ and 604 mg L⁻¹, respectively. Ammonia removal has reached maximal rates of 0.061 kgNH₄⁺-N (m³ h)⁻¹ and 0.041 kgNH₄⁺-N (m³ h)⁻¹, respectively. A maximum nitrite removal rate of 0.211 kgNO₂⁻-N (m³ h)⁻¹ was observed during the strengthening denitrification. The running time of one cycle was not fixed and was actually controlled by the system. The results indicated that the running period was more closely related to influent ammonia concentration than influent COD concentration. The aeration times could be shortened and the energy could be saved. The autocontrol two-stage hybrid process is therefore an economical and effective way for landfill leachate treatment.     

Absorption kinetics of NO from simulated flue gas using Fe(II)EDTA solutions

The absorption of NO encountering flue gases in aqueous solutions of Fe(II)EDTA was determined using a semi-batch stirred tank with a plane gas–liquid interface at 50 °C. The concentrations of NO, SO₂ and O₂ in the feeding stream were 300–800 ppm, 500–2200 ppm and 0–20%, respectively. The pH value of the Fe(II)EDTA solutions varied from 3 to 11. The concentrations of Fe(II)EDTA were maintained between 0.01 and 0.05 M. Experiments were performed to evaluate the effect of operating parameters on the NO absorption rate, the reaction kinetics of the reactants in gas and liquid phases, and the effect of competition between various reactants on the mass transfer rate in the NO removal system. Results indicate that the average reaction rate constant is 3.70 × 10⁷ M⁻¹ s⁻¹. Adding NaOH does not increase the absorption capability of Fe(II)EDTA. The presence of O₂ decreases the NO absorption rate with Fe(II)EDTA. The absorption rate of NO with Fe(II)EDTA decreases at low concentrations of SO₂, but increases at high concentrations.     

Treatment of gray water using anaerobic biofilms created on synthetic and natural fibers

Gray water treatment and reuse is an immediate option to counter the upcoming water shortages in various parts of world, especially urban areas. Anaerobic treatment of gray water in houses is an alternative low cost, low energy and low sludge generating option that can meet this challenge. Typical problems of fluctuating VFA, low pH and sludge washout at low loading rates with gray water feedstock was overcome in two chambered anaerobic biofilm reactors using natural fibers as the biofilm support. The long term performance of using natural fiber based biofilms at moderate and low organic loading rates (OLR) have been examined. Biofilms raised on natural fibers (coir, ridge-gourd) were similar to that of synthetic media (PVC, polyethylene) at lower OLR when operated in pulse fed mode without effluent recirculation and achieved 80–90% COD removal at HRT of 2 d showing a small variability during start-up. Confocal microscopy of the biofilms on natural fibers indicated thinner biofilms, dense cell architecture and low extra cellular polymeric substances (EPS) compared to synthetic supports and this is believed to be key factor in high performance at low OLR and low strength gray water. Natural fibers are thus shown to be an effective biofilm support that withstand fluctuating characteristic of domestic gray water.     

采用Mg(OH)2调节pH值对富磷剩余污泥厌氧消化过程氮磷释放的影响

以A/O工艺排出的富磷剩余污泥为对象,通过两组厌氧消化反应器(1组目标,1组对照),对比研究了Mg(OH)2作为pH值调节剂对污泥厌氧消化过程氮磷释放的影响。结果表明,Mg(OH)2在促进污泥水解的同时,可以有效降低消化液中NH4+-N、PO34--P质量浓度。经过21 d消化,目标反应器中VSS比对照试验多削减10%,但上清液中NH4+-N、PO4--P质量浓度仅为对照的25%、10%。消化后污泥中灰分增加,导致污泥浓缩与脱水性能显著提高。     

Biohydrogen production using waste activated sludge as a substrate from fructose-processing wastewater treatment

Biohydrogen production by dark fermentation in a series of batch tests under different environmental control conditions was evaluated to determine the optimal initial cultivation pH and temperature for a continuous-flow kinetic test to validate the kinetic model system. The waste activated sludge (WAS) from fructose-processing manufacturing was used as the model substrate for biohydrogen production. The batch experiments for biohydrogen production were conducted in a 6 l bioreactor. Fifteen batch kinetic tests were investigated when pH was controlled at 6, 7, 8 and 9 as well as the temperature was controlled at 37 °C, 45 °C and 55 °C, respectively. The experimental results indicated that the optimal operational condition for hydrogen production occurred while pH was 7 and temperature was 55 °C with the highest hydrogen production of 7.8 mmol. The optimal recovery time for hydrogen was 25 h in the batch experiments. Furthermore, the kinetic test of biohydrogen production was performed by anaerobic mixed microbial culture in the continuous-flow experiment when pH and temperature was maintained at 7 and 55 °C. Approximately 60% and 7% of substrate solution was converted into acetate and hydrogen, respectively, at the steady state. Roughly only 0.77% and 2.7% of substrate solution was converted into propionate and butyrate, respectively, at a steady-state condition. The experimental and modeling approaches presented in this study could be employed for the design of pilot-scale and full-scale anaerobic biohydrogen fermentors using food-processing waste activated sludge (WAS) as a substrate solution.     

预涂动态膜-生物反应器处理人工废水的试验研究

以公称孔径为1 μm的聚丙烯无纺布(NWF)为基膜,分别以粉末状活性炭、粉末状活性炭及聚合氯化铝为预涂剂,制作预涂动态膜膜组件,组成预涂动态膜-生物反应器处理人工废水.结果表明,预涂动态膜-生物反应器出水COD值低且稳定,粉末状活性炭预涂膜-生物反应器出水COD平均值为49 mg/L,粉末状活性炭及聚合氯化铝预涂膜-生物反应器出水COD平均值为29 mg/L,而NWF-膜生物反应器出水COD为54 mg/L.膜生物反应器对污染物质的去除虽然主要依靠活性污泥混合液,但附着在基膜上的动态膜的吸附、混凝作用也能去除部分污染物质.预涂膜能减少及防止污染物质向膜材料表面和内部扩散,减轻膜污染,使预涂动膜-生物反应器显示出一定的耐污染性能.但粉末状活性炭粒径过小,影响粉末状活性炭预涂动态膜-生物反应器的出水浊度(平均值为3.3 NTU);而粉末状活性炭与聚合氯化铝形成的预涂动态膜,在提高COD去除效率的同时,能减少活性炭对出水浊度(平均值为2.3 NTU)的影响,保证出水水质.     

Experimental study on the relationship between the charge amount of polypropylene granules and the frequency of electrostatic discharges while silo loading

This paper is a report on the relationship between the charge amount (charge to mass ratio, q/m) of polypropylene (PP, 2–3 mm) granules and the frequency of electrostatic discharges that occur while loading a metal silo. The feedback control system was used in order to control the q/m of PP granules. The electrostatic discharges inside the silo were also observed using a conventional image-intensifier system. The charging control range for PP granules was from 0 to −12 μC/kg in the q/m. The results obtained from the experiments show that (1) two kinds of electrostatic discharges were clearly observed inside a metal silo while loading PP granules, i.e., brush discharges and incendiary bulk surface discharges; (2) the number of brush discharges and incendiary bulk surface discharges increased with the increase in the q/m of PP granules, almost reaching saturation; and (3) brush discharges and incendiary bulk surface discharges began to occur at the −1.16 μC/kg and −2.33 μC/kg points in the q/m, respectively, in this study.     

Disintegration of municipal waste activated sludge by simultaneous combination of acid and ultrasonic pretreatment

The individual and simultaneous effects of acid and ultrasonic pretreatment on the disintegration of municipal waste activated sludge (WAS) were investigated based on chemical properties of WAS. In the combination of acid and ultrasonic pretreatment methods (ultrasonic-acid pretreatment), lowering pH accelerated and enhanced the disintegration of waste biological sludge. Therefore, the same disintegration efficiency (obtained by ultrasonic pretreatment alone) was achieved by the combined pretreatment in shorter sonication times. Optimum pretreatment conditions were ultrasonic power density of 1.0 W/mL and pretreatment time of 10 min for ultrasonic pretreatment alone, and ultrasonic power density of 1.0 W/mL, pretreatment time of 10 min and initial sludge pH of 2.0 for the combined pretreatment. Sludge disintegration degrees were about 30% and 40% under these optimized conditions, respectively. Optimum sludge concentration was found to be 1.0% total solid (TS) content for the combined pretreatment. As a result, ultrasonic-acid pretreatment has been determined as a new and effective combined sludge pretreatment method to improve the sludge disintegration.     

Improving disintegration and acidification of waste activated sludge by combined alkaline and microwave pretreatment

The individual alkaline or microwave pretreatment has been proved to be effective in disintegration and acidification of waste activated sludge (WAS). In this study, the effects of combined alkaline and microwave pretreatment at different pH and specific energy input (Es) on WAS disintegration were investigated using response surface methodology (RSM). Combined pretreatment achieved disintegration degree (DD) of 65.87% at Es of 38,400 kJ/kg TS and pH 11.0. The ANOVA further demonstrated that pH showed more significant effect on DD than Es. Anaerobic batch experiment results showed that combined pretreatment not only significantly improved volatile fatty acids (VFAs) accumulation but also shortened the time for the highest VFAs accumulation. The maximal VFAs accumulation (1500 mg COD/L) obtained at Es of 28,800 kJ/kg TS and fermentation time of 72 h, which was about two times that of the treatment without microwave (850 mg COD/L) at 96 h. The analysis of VFAs composition showed that the VFAs mainly consisted of acetic and iso-valeric acids, accounting for 57.3–70.1% of total VFAs.