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1

Anaerobic Co-Digestion of Sewage Sludge and Waste in High Solid State

Aboulfotoh Ahmed M., Marie Ahmed I., El-Hefny Rehab

Journal of Ecological Engineering

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2022

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Vol. 23, nr 6

1--13

EN

In this study, the effect of thermal pre-treatment (TP) on the physical characteristics and co-digestion of a mixture of food waste and sludge was investigated. The food waste (FW) to sewage sludge (SS) ratio used in this research is 1:2 (VS-based) to form a final concentration of 11.20%. The inoculum to substrate ratio was set at 1:1 (volumebased). Undoubtedly, the results show that TP has changed the physical characteristics of the food waste to sewage sludge mixture. The results show that the pretreatment increased the biogas production from 4385 ml for the untreated reactor to 5685 for the reactor R2(140) at 140 °C and the improvement in biogas production reaches 29.65% in the reactor R2(140) and the removal of volatile solids was 58.90%. Therefore, after the biomethane potential test, the temperature of 140 °C was found to be optimal in the production of biogas. The optimal condition is to use a mixture of pre-treated SS at the temperature of 140 °C and untreated FW, so TP is recommended to be used in anaerobic digestion of the mixture of food waste and sewage sludge.

2

Identification and Characterization of Potential Feedstock for Biogas Production in South Africa

Sawyerr Nathaniel, Trois Cristina, Workneh Tilahun

Journal of Ecological Engineering

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2019

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Vol. 20, nr 6

103--116

EN

Biogas is produced during anaerobic digestion (AD) of biodegradable organic materials and is considered a promising renewable energy resource. Feedstocks are essential to ensure the successful anaerobic digestion in biogas digesters. Therefore, the search of appropriate substrates has come into focus. In this study, we examined the potential substrates that could be used as feedstock for the successful operation of an anaerobic digester. The approach used in this study was to identify the potential feedstocks that can be converted into value-added products. The identification of the feedstocks was done based on classification and evaluation of the theoretical biogas and methane production during the digestion process. The results show that all the considered substrates exhibited the biogas theoretical yield, with cattle manure producing the highest yield (0.999 m3/kg VS), whereas the lowest biogas yield (0.949 m3/kg VS) was obtained from cassava peels. It was concluded that the use of cassava co-digested with fruit and vegetable waste as an alternative feedstock offers a greater potential in terms of biogas production and could thus be implemented in the biogas projects running with cow dungs inside South Africa, especially in rural communities.

3

Skuteczność wytwarzania biogazu w procesie współfermentacji metanowej biomasy mikroglonów i kiszonki kukurydzy

Dębowski M., Zieliński M., Kisielewska M., Dudek M., Romanowska-Duda Z.

Ochrona Środowiska

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2018

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Vol. 40, nr 3

15--20

PL

Rozwój zrównoważonego rynku bioenergii opiera się obecnie na uprawach energetycznych, których zwiększona produkcja konkuruje ze światowym zaopatrzeniem w żywność oraz paszę. W związku z tym jest potrzeba poszukiwania alternatywnej biomasy energetycznej z roślin nie przeznaczonych do spożycia. Alternatywę stanowi biomasa mikroglonów, która może być produkowana niezależnie od wykorzystania gruntów rolnych. Mając to na uwadze, przeprowadzono badania laboratoryjne (w reaktorach mezofilowych pracujących w systemie ciągłym) nad określeniem potencjału biomasy mikroglonów, jako surowca do współfermentacji metanowej z kiszonką z kukurydzy (Zea mays), w celu zwiększenia wydajności wytwarzania biogazu i metanu. Na podstawie uzyskanych wyników badań wykazano, że dodatek biomasy mikroglonów do kiszonki kukurydzy poprawił wartość stosunku C/N, w porównaniu do pojedynczych substratów fermentacyjnych. Największą ilość metanu (3045 cm3/d) oraz największą wydajność wytwarzania biogazu (628 cm3/g – w odniesieniu do suchej masy organicznej) uzyskano wówczas, gdy biomasa mikroglonów stanowiła 40% mieszaniny poddanej fermentacji, a stosunek C/N wynosił 17,53.

EN

Development of a sustainable bioenergy market is based these days on energy crops, increased production of which competes with global food and feed supply. Consequently, there is a need to identify an alternative energy biomass of non-food plant species. The microalgae biomass offers such an alternative as it may be produced independently of farm land use. Therefore, laboratory studies (continuous reactors, mesophilic conditions) were carried out to investigate the potential of microalgae biomass as a feedstock for methane codigestion with the energy crop Zea mays silage, with the aim to enhance biogas/methane yield. The results showed that mixing of the maize silage with microalgae biomass improved the C/N ratio when compared to the individual fermentation substrates. The highest methane and biogas production (3 045 cm3/d and 628 cm3/g per dry mass, respectively) were achieved when microalgae biomass constituted 40% of the feedstock and the C/N ratio was 17.53.

4

Co-digestion of sewage sludge and mature landfill leachate in pre-bioaugmented system

Montusiewicz A.

Journal of Ecological Engineering

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2014

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Vol. 15, nr 4

98--104

EN

The study examined the effects of co-digestion of sewage sludge and mature landfill leachate at the volumetric ratio of 95:5% in primarily bioaugmented system. Bioaug-mentation was carried out with the use of commercial product Arkea® in the volumet-ric dose of 5% and lasted three months prior to the co-digestion start-up. Co-digestion was undergone without bioaugmentation. The results indicated that in the first period (of three months) following bioaugmentation, co-digestion led to biogas/methane yields only 5-8% lower as compared to anaerobic digestion of sewage sludge, and the differences were not statistically significant. Moreover, a comparable value of vola-tile solids removal was obtained. However, the effects became worse over time, i.e. a lower organics removal efficiency of 16% as well as 9.5–13% decreases of biogas/ methane yields were achieved by applying co-digestion for a further period (of the same duration). Co-digestion of sewage sludge and mature landfill leachate could be recognized as quite efficient in the system that was primarily bioaugmented with the use of Arkea®. However, the beneficial impact of bioaugmentation remained for the limited period of three months after its completion. To sustain the favourable effects a periodical, repeatable bioaugmentation of the co-digestion system is required.

5

Methane production during laboratory-scale co-digestion of cattle slurry with 10 wt. % of various biowastes

Rusín J., Chamrádová K., Obroučka K., Kuča R.

Polish Journal of Chemical Technology

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2012

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Vol. 14, nr 1

14-20

EN

The paper summarizes the results from twenty model tests of continuous one-stage mesophilic anaerobic co-digestion of cattle slurry (90 wt. %) and various biowastes (10 wt. %). Digestion was conducted in 0.06 m3 reactors with hydraulic retention times ranging from 60 to 98 days during the research period 2007-2010. Methane production intensity and specific methane production are discussed. The highest methane production intensity (0.85 mN3.m-3.d-1) was from a mixture of 63 wt. % of total solids from biscuit meal EKPO - EB and from 37 wt. % of total solids from cattle slurry. The highest specific methane production from 1 kg of added organic compounds (0.67 mN3.kgVSp-1) was given by a mixture containing 61 wt. % of total solids using spring barley Aksamit (milled grain) and 39 wt. % of total solids from cattle slurry. The highest substrate-specific methane production (0.92 mN3.kgVSp-1) was from milled grains of winter rye Aventino.