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1.
Co‐digestion studies were carried out for biogas generation using fleshings as the primary substrate and a mixture of primary and secondary sludge generated during the treatment of tannery wastewater as the co‐substrate. Steapsin, a commercial grade lipase, was added to enhance the hydrolysis in anaerobic co‐digestion. The lipase dosages used were ranging between 0.25 and 1.0 g for a volatile solids input of 7.5 g. The performance of the co‐digestion was assessed from the volume of biogas generated. Experimental results revealed an optimum lipase dosage of about 0.75 g. At this dosage, the biogas generation was observed to increase by about 15% compared to that in the control without adding lipase. Further, the digestion with lipase addition was observed faster since the digestion period was reduced about 30%. This means that the capacity of the digester could also be reduced about 30% leading to savings in its installation cost.  相似文献   

2.
A comparative study of methane recovery by co-digesting kitchen waste and saline sewage sludge is performed to evaluate its feasibility for waste minimization. The experiment is performed at 37 °C having a mixing speed of 100 rpm and pH of 6.49–7.5 in anaerobic mixed batch reactors. The higher salinity level of the saline sewage sludge reduces the degradation rate of kitchen waste causing an enhancement in soluble chemical oxygen demand by 133% compared with 280% when co-digesting with the non-saline sample. The inhibitory behavior is in line with the low volatile solid elimination efficiency of 31% of saline against 55% of non-saline sludge. The Gompertz modeling, based on the outcomes, fits the cumulative methane generation trends quite well, with a strong correlation coefficient (>0.994). Besides, use of the non-saline sludge results in three times more methane production than the saline sample digestion. Sludge recovery is 0.07 m3 sludge m−3 wastewater, and water recovery is 0.84 m3 m−3 wastewater. The liquid produced from the fermentation of the slurry can be used for irrigation as well as fertilization. Kitchen waste co-digestion with both sludge samples has been proven to be a practical method for exploiting the extra digestion capacity of wastewater treatment plants currently in operation, but it is more practical for non-saline sludge.  相似文献   

3.
Sulfate‐reduction data from various anaerobic reactor configurations, e. g., upflow anaerobic sludge blanket reactor (UASBR), completely stirred tank reactor (CSTR), and batch reactor (BR) with synthetic wastewaters, having glucose and acetate as the substrates and different levels of sulfate, were evaluated to determine the level of sulfate‐reducing activity by sulfate‐reducing bacteria coupled to organic matter removal. Anaerobic reactors were observed for the degree of competition between sulfate‐reducing sulfidogens and methane producing bacteria during the degradation of glucose and acetate. Low sulfate‐reducing activity was obtained with a maximum of 20% of organic matter degradation with glucose‐fed upflow anaerobic sludge bed reactors (UASBRs), while a minimum of 2% was observed with acetate‐fed batch reactors. The highest sulfate removal performance (72–89%) was obtained from glucose fed‐UASB reactors, with the best results observed with increasing COD/SO4 ratios. UASB reactors produced the highest level of sulfidogenic activity, with the highest sulfate removal and without a performance loss. Hence, this was shown to be the optimum reactor configuration. Dissolved sulfide produced as a result of sulfate reduction reached 325 mg/L and 390 mg/L in CST and UASB reactors, respectively, and these levels were tolerated. The sulfate removal rate was higher at lower COD/SO4 ratios, but the degree of sulfate removal improved with increasing COD/SO4 ratios.  相似文献   

4.
The effect of a reactive azo dye (the hydrolyzed form of Reactive Orange 107, HRO107) on the digestion of municipal waste sludge (WS) was studied. The study also focused on the effect of acclimation of the anaerobic mixed culture on dye treatment. Anaerobic batch assays were carried out in serum bottles under mesophilic conditions. Unacclimated and acclimated anaerobic mixed cultures were used for the study. Both unacclimated and acclimated anaerobic cultures completely reduced HRO107 during WS digestion. Inhibitory HRO107 concentration was found to be 800 mg/L for unacclimated mixed culture. Acclimation increased the inhibitory concentration level from 800 to 3200 mg/L. Sulfanilic acid and four other unidentified dye reduction end products were detected at the end of the assays. The results of this study indicated that anaerobic municipal WS digesters have the potential to be a cost efficient and effective pre treatment method.  相似文献   

5.
Methane fermentation is widely used to dispose of sewage sludge at wastewater treatment plants (WWTPs), due to production of renewable energy in the form of biogas. Antibiotics present in wastewater may accumulate in a sewage sludge. The aim of the present study is to investigate the impact of three antibiotics from different classes in three different doses on methane production from sewage sludge. For this purpose, metronidazole (MET), amoxicillin (AMO), and ciprofloxacin (CIP) are individually added to anaerobic reactors with sewage sludge collected from municipal WWTP. The antibiotics’ highest concentration (1024 mg kg?1 of AMO; 512 mg kg?1 of MET and CIP) lowers methane production and methane content in biogas. MET exerts the most marked effect and lowers methane production to 36.8 ± 3.7 mL CH4 kg?1 volatile solids. Tested antibiotics probably inhibit methanogenic archaea, which results in volatile fatty acids (VFAs) accumulation. Addition of MET results in accumulation of many kinds of VFAs with the highest concentration of acetic acid (17.52 ± 1.85 g L?1). The addition of of AMO results in accumulation of butyric acid only (253.00 ± 15.89 g L?1). However, addition of CIP results in accumulation of mainly acetic acid (7.58 ± 0.82 g L?1) and isovaleric acid (2.01 ± 0.41 g L?1). Next, synergistic effect of these antibiotics in a low concentration of 16 mg kg?1 of AMO, 8 mg kg?1 of MET, and 2 mg kg?1 of CIP is measured in semi‐continuous conditions and causes inbibition of methane production and accumulation of VFAs.  相似文献   

6.
Sludge pretreatment prior to anaerobic digestion has been found to reduce sludge production in wastewater treatment. Sludge disintegration using physical, chemical, biological, or mechanical methods can increase biogas production and reduce sludge quantities. Ultrasonication is one of the most effective means of mechanical disintegration. This study aims to investigate ultrasonication as a means for solubilizing waste activated sludge (WAS) to enhance its digestability. Sonication was applied by the use of two different probes providing different powers and energies into the sludge after which the soluble chemical oxygen demand (sCOD) increases were measured. The samples were then digested anaerobically in 250 mL serum bottles for about 50 days. Along with the biogas measurements, the rate of methane production is calculated to be able to quantify the effect of pretreatment and compare the results between different applications. The results showed that with the increase of sonication power and sonication time, sCOD increased. An introduction of higher sonication energy made the sCOD rise sharply, however, this increase was not indefinite; it became gradually lower with the further increase of energy. The results indicated that specific methane production, specific methane yield, and the first order methane generation rate increased with increasing energy input.  相似文献   

7.
Effectiveness of ultrasonication, microwave technologies, and enzyme addition prior to anaerobic digestion is investigated using sludge samples taken from the secondary settling tank of a domestic wastewater treatment plant to improve methane production, enhance dewaterability characteristics of the sludge, and to reduce excess sludge. Microwave pre‐treatment (1500 W, 10 min at 175 °C) results in better extra digester performance (compared to the control reactor) in terms of methane production (25 m3 ton?1 suspended solids (SS)) than ultrasound (no improvement) and enzyme pre‐treatment (11 m3 ton?1 SS). While methane production is not improved as a result of ultrasonication pre‐treatment (15 000 kJ kg?1 SS), a noticeable increase (19%) is observed in the case of microwave pre‐treatment. Higher compactibility values are obtained after ultrasonication and microwave application compared to the control (i.e., from 7.1 to 8.7 and 9.2%, respectively) before anaerobic digestion. Although ultrasonication and microwave application decrease the dewaterability of the raw sludge (capillary suction time (CST) from 827 to 1364 and 2290 s, respectively), similar dewaterability results are obtained at the end of the anaerobic digestion process for all pre‐treated sludge samples. An economic assessment of this study shows that pre‐treatment with microwave results in more than 10‐fold less net cost compared to the enzyme application.  相似文献   

8.
Anaerobic digestion (AD) is an effective way to convert animal manures into profitable by‐products while simultaneously reducing the pollution of water, air, and soil caused by these wastes. Conventional high‐rate anaerobic reactors cannot effectively process animal manures with high solids‐containing wastes. The two‐phase configuration for AD has several advantages over conventional one‐phase processes, e. g., increased stability of the process, smaller size and cost efficient process configurations. In the present study, the experiments were carried out in a two‐phase system composed of an acidogenic reactor and a methanogenic reactor, and in a one‐phase system composed of only a methanogenic reactor. The reactors were operated as unmixed (without an external mixing aid), unsophisticated, and daily‐fed mode. It was found that the two‐phase configuration was more efficient than the one‐phase system. The biogas production in the two‐phase system at a hydraulic retention time (HRT) of 8.6 days (only methanogenic phase) was calculated to be 42% higher at an organic loading rate (OLR) of 3.5 g VS/L·day than that of the one‐phase with a HRT of 20 days. This translates into significant performance improvement and reduced volume requirement. This finding represents a further step in the achievement of wider use of simple anaerobic reactor configurations for waste treatment in rural areas.  相似文献   

9.
This study investigated the effectiveness of a new packing material, namely mixed rice husk silica with dried activated sludge for removing H2S. Dried sewage sludge was collected from Putrajaya sewage treatment plant in Malaysia. Rice husk silica was prepared at temperature of 800°C, after acid leaching and mixed with dried sewage sludge to be utilized in a polyvinyl chloride filter. The system was operated under variable conditions of two parameters, different inlet gas concentration and different inlet flow rate. H2S was passed through the filter with one liter of the packing material. More than 99.96% removal efficiency (RE) with empty bed residence time (EBRT) of 90–45 s and 300 ppm inlet concentration was observed. However, the RE decreased to 96.87% with the EBRT of 30 s. The maximum elimination capacity (EC) of 52.32 g/m3/h was obtained with the RE of 96.87% and H2S mass loading rate of 54 g/m3/h, while at the RE of 99.96%, maximum EC was 26.99 g/m3/h with the H2S mass‐loading rate of 27 g/m3/h. A strong significant correlation between increasing of H2S mass loading rate and pressure drop was also detected (p < 0.01). Maximum pressure drop was 3.0 mm H2O after 53 days of operating time, the EBRT of 30 s, and 54 g/m3/h of H2S loading rate. These observations suggest that the mixture of rice husk silica with dried activated sludge is a suitable physico‐biological filter for H2S removal.  相似文献   

10.
The aim of this study is to evaluate the feasibility of sludge digester effluent as feeding solution to enrich anaerobic ammonium oxidation (anammox) bacteria. The performance of the two parallel pilot scale‐upflow packed bed anammox reactors (UPBAn1 and UPBAn2) are examined in terms of the enrichment of anammox bacteria. The control experiment is set up conducting synthetic wastewater as feeding solution in the UPBAn1 reactor whereas, the sludge digester effluent is fed to the nitritation reactor and then the partially nitrated digester effluent to the UPBAn2 reactor. Anammox activities are evaluated by mass balances based on ammonium (NH4+), nitrite (NO2?), and nitrate (NO3?) analysis and NRR. Microbial community of anammox bacteria is analyzed using real‐time polymerase chain reaction (PCR). The results demonstrate that UPBAn 1 and UPBAn2 reactors are successfully enriched on days 64 and 40 with NRRs of 19.54 and 19.43 g N m?3 per day, respectively. This study reveals that both synthetic wastewater and digester effluent are suitable for the enrichment of anammox bacteria; however, digester effluent as feeding solution for enrichment of anammox bacteria based on the ease of process control and process stability is more advisable.  相似文献   

11.
The fate of 14C‐labeled sulfamethoxazole and acetyl‐sulfamethoxazole in soil has been investigated with special respect to possible entry routes of human and veterinary pharmaceuticals into soil environments. Therefore, the stability of the test substances was monitored first in sewage sludge and bovine manure. Within the incubation period of 72 d, 1% at maximum of the initially applied radiotracers was released as 14C‐carbon dioxide while ?75% was transferred to non‐extractable residues that were operationally defined by the ethyl acetate extraction. Test‐sludge and test‐manure samples with defined aged residues were prepared and, supplementary to standard solutions, applied to silty‐clay soil samples. After standard and test‐sludge application, soil/water distribution coefficients of Kd < 5 L kg–1 were determined revealing both test substances as potential leachers. In contrast, the sorption of sulfamethoxazole increased after test‐manure application (Kd > 10 L kg–1). In the long‐term degradability tests, the metabolic fate of both test substances was characterized by the continuous decrease of extractable residues, resulting in disappearance times of DT90 ? 33 d, and the increase of non‐extractable residues. Mineralization reached 11% at maximum. Thereby, the dynamics of these processes differed whether the test substances were applied via standard, test‐sludge or test‐manure application. This fact emphasized the relevance of entry route specific matrix effects on the fate of both test substances in soil.  相似文献   

12.
Fenton process was investigated for the purpose of biological sludge disintegration. The Box–Wilson experimental design was employed to evaluate the effects of major process variables (Fe(II) and H2O2 concentrations) on both disintegration and dewatering performance of sludge. Results showed that 4 g Fe(II)/kg total solids (TSs) and 60 g H2O2/kg TS are efficient for floc disintegration. Fenton pre‐treatment enhanced the biodegradability of sludge. For 4 g Fe(II)/kg TS and 60 g H2O2/kg TS, 19.4% higher methane production was achieved compared to raw sludge in biochemical methane potential assay. Fenton pre‐treatment resulted in the release of organic sludge components into the liquid phase. For 4 g Fe(II)/kg TS and 60 g H2O2/kg TS, dissolved organic carbon and total nitrogen in sludge's supernatant increased by 75.74 and 60.60%, respectively. Fenton pre‐treatment enhanced the filterability of sludge and it can be applied for conditioning purpose before mechanical dewatering units.  相似文献   

13.
A start‐up study for biohydrogen production from palm oil mill effluent (POME) is carried out in a pilot‐scale up‐flow anaerobic sludge blanket fixed‐film reactor (UASFF). A substrate with a chemical oxygen demand (COD) of 30 g L?1 is used, starting with molasses solution for 30 days and followed by a 10% v/v increment of POME/molasses ratio. At 100% POME, a hydrogen content of 80%, hydrogen production rate of 36 L H2 per day, and maximum COD removal of 48.7% are achieved. Bio‐kinetic coefficients of Monod, first‐order, Grau second‐order, and Stover‐Kincannon kinetic models are calculated to describe the performance of the system. The steady‐state data with 100% POME shows that Monod and Stover‐Kincannon models with bio‐kinetic coefficients of half‐velocity constant (Ks) of 6000 mg COD L?1, microbial decay rate (Kd) of 0.0015 per day, growth yield constant (Y) of 0.786 mg volatile suspended solids (VSS)/mg COD, specific biomass growth rate (μmax) of 0.568 per day, and substrate consumption rate of (Umax) 3.98 g/L day could be considered as superior models with correlation coefficients (R2) of 0.918 and 0.989, respectively, compared to first‐order and Grau's second‐order models with coefficients of K1 1.08 per day, R2 0.739, and K2s 1.69 per day, a = 7.0 per day, b = 0.847.  相似文献   

14.
Glucose‐fed high‐rate UASB reactors were tested at three COD/SO4 ratios and hydraulic retention times to promote sulfate reducing activity and observe the effects on reactor performance. Different COD/SO4 ratios (20, 10, and 5) resulted in changes in organic matter removal, methane production, alkalinity, dissolved sulfide and biomass concentrations and profile. The COD removal dropped from 95 to 80–84 % at the lowest COD/SO4 ratio. Sulfate was removed at 79 to 89 % at the highest ratio and dropped to 72 to 74 % with increasing sulfate loading. Alkalinity was produced at higher levels with increasing sulfate loading. Specific methane production dropped with decreasing hydraulic retention times. Sulfate‐reducing activity used a maximum of 11.7 % of organic matter at the highest sulfate loading level, producing a slight shift to sulfate‐reducing activity in the substrate competition between sulfate‐reducing bacteria and methanogens. Increased sulfate loading at COD/SO4 ratios of 10 and 5 caused deterioration of the concentration profile of the sludge, resulting in biomass washout and decreased volatile fraction of biosolids in the reactors.  相似文献   

15.
A chemical-physical method for treatment of aniline containing waste water was developed. At the chemical stage aniline is polymerized by Fenton's reagent. Thus insoluble polyaniline precipitates. The best reaction conditions are: pH-value of 2–3, stepwise dosing of 60 mL H2O2 (30%) and 12 mL saturated FeSO4-solution per litre waste water. The molar ratio Fe(II): H2O2 amounts to 0.3:10. The concentration of aniline is reduced by this chemical treatment from about 20 g/L to 30–40 mg/L. By adsorption at activated charcoal the concentration of aniline can be reduced further to 0.2 mg/L. The resulting sludge can easily be dewatered in a chamber filter press.  相似文献   

16.
Phthalates are considered priority pollutants because of their potential adverse effects on ecosystems and human health. The objectives of this study were to determine the occurrence of five phthalates (DMP, DEP, DBP, BBP, and DEHP) in sewage sludge and to determine the seasonal variability of these contaminants at three (Bahçe?ehir, Pa?aköy, and Tuzla) full‐scale municipal and domestic wastewater treatment plants (WWTP) in Istanbul, Turkey. Mass balance was also calculated for DEHP at Tuzla WWTP sludge treatment units. DMP, DEP, DBP, BBP, and DEHP concentrations in sewage sludge ranged from 1.4 to 2.7 mg/kg dry weight (dw), 1.1 to 2.8, 0.6 to 4.6, 2.8 to 6.2, 18 to 490 mg/kg dw, respectively. Phthalate concentrations from the Bahçe?ehir and Pa?aköy WWTPs met the limit (100 mg/kg dw) of Turkey national sludge regulation and the Europe Union draft of sludge directive for land application, whereas phthalate concentrations from Tuzla WWTP exceeded the maximum permissible concentration. Phthalate concentrations did not show seasonal variations for Bahçe?ehir and Pa?aköy WWTPs, which receive mainly household wastewater while some fluctuations were observed DEP, DBP, and DEHP at Tuzla WWTP which has a lot of industrial wastewater contribution. The mass balance showed that approximately 17% of DEHP in the primary and secondary sludge was removed by anaerobic digestion, while 43% returned back to the beginning of the WWTP and 40% remained in the dewatered sludge. This study suggests that phthalates in sludge from WWTPs with industrial wastewater contribution may limit the use of sludge for land application.  相似文献   

17.
The contents of Ni and Cr in sewage sludge with high and low amounts of heavy metals were investigated by polarography. The DIN-digestion (aqua regia) was used, and the resulting solution was treated with H2O2/UV (90 °C, 60 min) for further destroying of the organic material. Besides, the solution of the DIN-digestion was examined with AAS (flame) and ICP-OES. With the determination of Ni it was shown that after digestion with aqua regia no further treatment with H2O2/UV is necessary. Contrariwise it was found that for the determination of Cr a H2O2/UV photolysis is necessary followed by further steps to get good agreement with AAS and ICP results as well as with the certified values of a sludge of the Community Bureau of Standards.  相似文献   

18.
Leachate treatment using a membrane bioreactor is an effective method. This study presents a configuration including an anaerobic bioreactor and a membrane module, called submerged anaerobic membrane bioreactor (SAnMBR), for treating influent with leachate/acetate rations (L/A), that were kept to be 10, 25, 50, 75, and 100% at a constant SRT (100 days). COD removal decreased from 85 to 75% when the L/A ratio increased from 10 to 100. To prevent membrane fouling, a SAnMBR was operated in the case of circulation of mixed liquor under continuous and intermittent suction. The average fluxes were 2.60 and 0.40 L/m2 h at the periods of intermittent and continuous suction, respectively. The methane production varied between 0.25 and 0.32 L CH4/g CODremoved.  相似文献   

19.
Laboratory‐scale batch experiments were conducted to investigate the adsorption behavior of eight fluoroquinolones (FQs) on aerobic, anoxic, and anaerobic sludge, under different adsorpiton time, pH, and temperature conditions. Results indicated that adsorption of FQs onto all sludge was a physical sorption process. The relationship of the partitioning coefficient (Kd) and the octanol/water partition coefficient (Kow) for each FQ was established. The adsorbed fraction of FQs on sludge could then be predicted with the Kd. It was calculated that about 50–72% of the FQs were adsorbed on the sludge. Therefore, the adsorption effect must be considered when studying the fate and occurrence of FQs in wastewater treatment systems.  相似文献   

20.
The differential-pulse polarography (DPP) and the stripping voltametry (SV) are investigated in detail with respect to their suitability for the quantitative detection of individual traces of heavy metals in sewage sludge. The results are checked on the basis of AAS analyses and by the standard-addition method. From the hydrochloric-acid extracts of fused sludge samples down to 1 μg/l can be detected by the SV, whereas the DPP reaches a sensitivity of 100 μg/l. The following basic electrolytes are used: Zn: 2 … 3 mol/l H3PO4; Cu: 0.4 mol/l K2CO3, 0.2 mol/l Na-K-tartrate, 0.1 mol/l HCl; Ni: 1 mol/l NH4OH, 1 mol/l NH4Cl, 25 ml/l triethylamine; Pb and Cd: 0.1 … 0.2 mol/l HCl.  相似文献   

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