Two-phase anaerobic co-digestion of food waste and sewage sludge

2014 ◽  
Vol 71 (1) ◽  
pp. 52-58 ◽  
Author(s):  
Feng Wang ◽  
Wei-Ying Li ◽  
Xue-Nong Yi

The feasibility and performance of food waste and sewage sludge co-digestion were investigated to gain insight into their resource utilization. In this study, two-phase anaerobic digestion (TPAD) was operated under a total solids mixing ratio of 1:1 and different sludge retention times (SRTs). Results show that an acidogenic reactor with a 5-day SRT obtained the highest acidification efficiency, and its acetic acid content was dominant. The organic removal rate of a methanogenic reactor (MR) with a 20-day SRT and its corresponding TPAD system with a 25-day SRT were both the highest among the MRs and TPAD systems. Volatile solids and total chemical oxygen demand average removal efficiencies of the TPAD system with a 25-day SRT reached 64.7 and 60.8%, respectively. The MR with a 30-day SRT obtained the minimum ratio of volatile fatty acid to alkalinity (0.12). The methane content generated from the different MRs fluctuated at around 70%. All of the above results can provide reference for future research.

2014 ◽  
Vol 852 ◽  
pp. 789-796 ◽  
Author(s):  
Guo Hua Wang ◽  
Lei Wang ◽  
Xue Jun Tan ◽  
Yi Xian Wang ◽  
Feng Wang

The impact of hydraulic retention time (HRT) on two-phase mesophilic (35°C) anaerobic co-digestion of food waste and sewage sludge was studied under mixing ratio of 1:1 on the TS basis. Laboratory-scale, two-phase anaerobic digestion systems were employed with each system consisting of an acidogenic reactor and a methanogenic reactor linked in series. For the acidogenic phase, an increase of volatile fatty acid (VFA) concentration was observed as HRT increased from 1d to 5d and the HRT of 5d was recommended for significantly higher VFA production and less propionate percentage, which could provide stable and favourable substrates for the methane reactor. Under acidogenic HRT of 5d, 20d was proved to be the optimum HRT for methanogenic phase with the methane content, methane production rate, methane yield and two-phase VS removal rate reached 71%, 0.7L/(L·d), 0.69L/gVSremoved and 64.7%, respectively. Results verified that the constraints of conventional anaerobic digestion for food waste or sewage sludge separately could be overcome by synergistic effect of co-digestion strategy and two-phase treatment.


Processes ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 231 ◽  
Author(s):  
Renata Xavier Alberico Freitas ◽  
Lara Aguiar Borges ◽  
Handray Fernandes de Souza ◽  
Fernando Colen ◽  
Alex Sander Rodrigues Cangussu ◽  
...  

The generation of large volumes of waste by industrial processes has become an object of study because of the necessity to characterize the composition of residues in order to suggest appropriate treatments and to minimize adverse environmental impacts. We performed analyses of total fixed and volatile solids, moisture, and chemical oxygen demand (COD). We found high organic matter content. We also measured physicochemical characteristics, including corrosivity, reactivity, and toxicity. Sewage sludge showed levels of chloride and sodium above the maximum allowed limits. These data suggest the potential for anaerobic digestion as a treatment option for sewage sludge and for its use as a biofertilizer.


2004 ◽  
Vol 49 (10) ◽  
pp. 147-154 ◽  
Author(s):  
J.-Y. Wang ◽  
O. Stabnikova ◽  
S.T.-L. Tay ◽  
V. Ivanov ◽  
J.-H. Tay

Biotechnology for intensive aerobic bioconversion of sewage sludge and food waste into fertilizer was developed. The wastes were treated in a closed reactor under controlled aeration, stirring, pH, and temperature at 60¡C, after addition of starter bacterial culture Bacillus thermoamylovorans. The biodegradation of sewage sludge was studied by decrease of volatile solids (VS), content of organic carbon and autofluorescence of coenzyme F420. The degradation of anaerobic biomass was faster than biodegradation of total organic matter. The best fertilizer was obtained when sewage sludge was thermally pre-treated, mixed with food waste, chalk, and artificial bulking agent. The content of volatile solid and the content of organic carbon decreased at 24.8% and 13.5% of total solids, respectively, during ten days of bioconversion. The fertilizer was a powder with moisture content of 5%. It was stable, and not toxic for the germination of plant seeds. Addition of 1.0 to 1.5% of this fertilizer to the subsoil increased the growth of different plants tested by 113 to 164%. The biotechnology can be applied in larger scale for the recycling of sewage sludge and food wastes in Singapore.


2020 ◽  
Vol 63 (1) ◽  
Author(s):  
Ji Su Bae ◽  
Yeo Myung Yoon ◽  
Seon Kyoung Shin ◽  
Dong Jin Lee ◽  
Dong Cheol Seo

Abstract The objective of this study was to determine methane yields (MY) of organic wastes in biogasification facilities according to the mixing ratio of food waste/food waste leachate and sewage sludge. One biogasification facility that treated sewage sludge only was compared with three biogasification facilities treating sewage sludge and food waste. The theoretical MY was derived based on analyses of carbohydrate, fat, and protein to examine the efficiency of the biogasification facility. The average actual MY was 0.424 Sm3CH4/kg volatile solids, which corresponded to 83.7% of theoretical MY. In the case of combined anaerobic digestion (CD) mixing with food waste/food waste leachate, inhibitory factors (volatile fatty acids [VFAs], total nitrogen [TN], and organic matter contents) showed the tendency to have relatively higher values in CD facilities than in the biogasification facility treating sewage sludge only. Mean concentrations of VFAs and TN in the anaerobic digester effluent, and the organic loading rate were 406 mg/L, 3,721 mg/L, and 1.62 kg volatile solids/m3 day, respectively. The influence of anaerobic digester effluent was in charge of 10% within the influent environmental loading rate from the sewage treatment plants associated with the biogasification facilities. Analyses of the microbial community showed that a remarkable change in the structure of methanogens was directly related to different MY in each plant. In particular, Methanoculleus and Methanosaeta increased with an increasing ratio of food waste/food waste leachate to sludge, while Methanococcus and Methanosarcina decreased. In conclusion, CD showed steady operational conditions and high efficiency of MY by injecting food waste/food waste leachate into the anaerobic digester. It met the current criteria for integrated treatment of organic waste in biogasification facilities in South Korea.


2016 ◽  
Vol 23 (1) ◽  
pp. 99-115 ◽  
Author(s):  
Agnieszka A. Pilarska ◽  
Krzysztof Pilarski ◽  
Kamil Witaszek ◽  
Hanna Waliszewska ◽  
Magdalena Zborowska ◽  
...  

Abstract The results of anaerobic digestion (AD) of buttermilk (BM) and cheese whey (CW) with a digested sewage sludge as inoculum is described. The substrate/inoculum mixtures were prepared using 10% buttermilk and 15% cheese whey. The essential parameters of the materials were described, including: total solids (TS), volatile solids (VS), pH, conductivity, C/N ratio (the quantitative ratio of organic carbon (C) to nitrogen (N)), alkalinity, chemical oxygen demand (COD). The potential directions of biodegradation of the organic waste types, as used in this study, are also presented. Appropriate chemical reactions illustrate the substrates and products in each phase of anaerobic decomposition of the compounds that are present in buttermilk and cheese whey: lactic acid, lactose, fat, and casein. Moreover, the biogas and biomethane production rates are compared for the substrates used in the experiment. The results have shown that buttermilk in AD generates more biogas (743 m3/Mg VS), including methane (527 m3/Mg VS), when compared with cheese whey (600 m3/Mg VS, 338 m3/Mg VS for biogas and methane, respectively).


2020 ◽  
Vol 26 (1) ◽  
Author(s):  
Hee-Jeong Choi

The purpose of this study was to investigate the effects of acidogenic fermentation broth with rice bran (RFFB), tap water (TFFB), or raw fishery by-products (FBs) on sludge reduction and biogas production in an anaerobic co-digestion process. Acidogenic fermentation of FBs with rice bran was faster and produced more volatile fatty acids than that with tap water. Reduction efficiencies for chemical oxygen demand, volatile solids, and total solids were highest in RFFB. In the kinetic analysis, λ (d), which represents the duration of the lag phase, was shortest with RFFB (1.09 d) and highest in sewage sludge (8.86 d). As the loading amount of volatile solids and chemical oxygen demand increased, the amount of cumulative biogas also increased. Amount of produced methane and energy recovery were highest with RFFB (5.71 kWh). Anaerobic co-digestion of FFB and sewage sludge allowed reduced sludge and recovered energy using the discarded waste as an organic carbon source.


2016 ◽  
Vol 73 (12) ◽  
pp. 3072-3079 ◽  
Author(s):  
C. Schaum ◽  
D. Lensch ◽  
P. Cornel

Abstract The composition of sewage sludge and, thus, its energetic potential is influenced by wastewater and wastewater treatment processes. Higher or lower heating values (HHV or LHV) are decisive factors for the incineration/gasification/pyrolysis of sewage sludge. The HHV is analyzed with a bomb calorimeter and converted to the LHV. It is also possible to calculate the heating value via chemical oxygen demand (COD), total volatile solids (TVS), and elemental composition. Calculating the LHV via the COD provides a suitable method. In contrast, the correlation of the HHV or LHV with the TVS is limited. One prerequisite here is a constant specific energy density; this was given with the types of sewage sludge (primary, surplus/excess, and digested sludge) investigated. If the energy density is not comparable with sewage sludge, for instance with the co-substrate (bio-waste, grease, etc.), the estimation of the heating value using TVS will fail. When calculating the HHV or LHV via the elemental composition, one has to consider the validity of the coefficients of the calculation equation. Depending on the organic composition, it might be necessary to adjust the coefficients, e.g. when adding co-substrates.


2015 ◽  
Vol 768 ◽  
pp. 281-288
Author(s):  
Lian Hai Ren ◽  
Yan Bing Huang ◽  
Pan Wang

The variations of daily biogas yields, cumulative biogas yields, biogas composition analysis, total solids (TS) and volatile solids (VS) were studied in the process of mesophilic and dry anaerobic digestion of food waste under different oil contents (0%, 2%, 4%, 6%, 8%, 10%) at 35 °C. The gas production raised and then went down with the oil content, followed by 243.14, 245.64, 256.09, 269.25, 276.54, 284.22mL /g TS respectively. The research provided a reference for the pretreatment of food waste in follow-up continuous fermentation. Results showed that the period of the process of mesophilic dry anaerobic digestion under oil content of 0% was the shortest, with the total biogas production of 1275.5mL. During the process of the digestion, methane content of the biogas raised and then went down, up to a maximum of 77.62%. The removal rate of TS and VS in food waste with the oil content of 6% was the highest, obtained as 11.2% and 13.2%, respectively.


Author(s):  
Zuhaib Siddiqui ◽  
N.J. Horan ◽  
Kofi Anaman

Biomethane production from processed industrial food waste (IFW) in admixture with sewage sludge (primary and waste activated sludge: PS and WAS) was evaluated at a range of C:N ratios using a standard biochemical methane potential (BMP) test. IFW alone had a C:N of 30 whereas for WAS it was 5.4 and thus the C:N ratio of the blends fell in that range. Increasing the IFW content in mix improves the methane potential by increasing both the cumulative biogas production and the rate of methane production. Optimum methane yield 239 mL/g VSremoved occurred at a C:N ratio of 15 which was achieved with a blend containing 11 percent (w/w) IFW. As the fraction of IFW in the blend increased, volatile solids (VS) destruction was increased and this led to a reduction in methane yield and amount of production. The highest destruction of volatile solids of 93 percent was achieved at C:N of 20 followed by C:N 30 and 15. A shortened BMP test is adequate for evaluating optimum admixtures.


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