Abstract: The estimation of overall on-site and off-site greenhouse gas (GHG) emissions by wastewater treatment plants revealed that in anaerobic and hybrid treatment systems greater emissions result from off-site processes compared to on-site processes. However, in aerobic treatment systems, onsite processes make a higher contribution to the overall GHG emissions. The total GHG emissions were estimated to be 1.6, 3.3 and 3.8 kg CO2-e/kg BOD in the aerobic, anaerobic and hybrid treatment systems, respectively. In the aerobic treatment system without the recovery and use of the generated biogas, the off-site GHG emissions were 0.65 kg CO2-e/kg BOD, accounting for 40.2% of the overall GHG emissions. This value changed to 2.3 and 2.6 kg CO2-e/kg BOD, and accounted for 69.9% and 68.1% of the overall GHG emissions in the anaerobic and hybrid treatment systems, respectively. The increased off-site GHG emissions in the anaerobic and hybrid treatment systems are mainly due to material usage and energy demand in these systems. The anaerobic digester can contribute up to 100%, 55% and 60% of the overall energy needs of plants in the aerobic, anaerobic and hybrid treatment systems, respectively.
Abstract: This paper describes technological possibilities to
enhance methane productionin the anaerobic stabilization of wastewater treatment plant excess sludge. This objective can be achieved by the addition of waste residues: crude glycerol from biodiesel production and residues from fishery. The addition
ofglycerol in an amount by weight of 2 – 5% causes enhancement of methane production of about 250 – 400%. At the same time the
percentage increase of total solids concentration in the outgoing sludge is ten or more times less. The containment of methane in
biogas is higher in case of admixed substrate.
Abstract: In this research, an anaerobic co-digestion using decanter cake from palm oil mill industry to improve the biogas production from frozen seafood wastewater is studied using Continuously Stirred Tank Reactor (CSTR) process. The experiments were conducted in laboratory-scale. The suitable Hydraulic Retention Time (HRT) was observed in CSTR experiments with 24 hours of mixing time using the mechanical mixer. The HRT of CSTR process impacts on the efficiency of biogas production. The best performance for biogas production using CSTR process was the anaerobic codigestion for 20 days of HRT with the maximum methane production rate of 1.86 l/d and the average maximum methane production of 64.6%. The result can be concluded that the decanter cake can improve biogas productivity of frozen seafood wastewater.
Abstract: The use of renewable energy sources incl. biogas has become topical in accordance with the increasing demand for energy, decrease of fossil energy resources and the efforts to reduce greenhouse gas emissions as well as to increase energy independence from the territories where fossil energy resources are available.
As the technologies of biogas production from agricultural biomass develop, risk assessment and risk management become necessary for farms producing such a renewable energy. The need for risk assessments has become particularly topical when discussions on changing the biogas policy in the EU take place, which may influence the development of the sector in the future, as well as the operation of existing biogas facilities and their income level.
The current article describes results of the risk assessment for farms producing biomass from agriculture biomass in Latvia, the risk assessment system included 24 risks, that affect the whole biogas production process and the obtained results showed the high significance of political and production risks.
Abstract: This paper discusses the utilization of marine biomass as an energy resource in Japan. A marine biomass energy system in Japan was proposed consisting of seaweed cultivation (Laminaria japonica) at offshore marine farms, biogas production via methane fermentation of the seaweeds, and fuel cell power generation driven by the generated biogas. We estimated energy output, energy supply potential, and CO2 mitigation in Japan on the basis of the proposed system. As a result, annual energy production was estimated to be 1.02-109 kWh/yr at nine available sites. Total CO2 mitigation was estimated to be 1.04-106 tonnes per annum at the nine sites. However, the CO2 emission for the construction of relevant facilities is not taken into account in this paper. The estimated CO2 mitigation is equivalent to about 0.9% of the required CO2 mitigation for Japan per annum under the Kyoto Protocol framework.
Abstract: Biogas, a clean renewable energy, is attracting a growing
concern of researchers and professionals in many fields. Based
on the natural and climatic conditions in semi-arid regions of northwestern
China, the present study introduces a specifically-designed
family-size biogas plant (with a digester of 10m3) with manure
and urine of animals and humanity as raw materials. The biogas
plant is applicable to areas with altitudes of more than 2000 meters
in northwestern China. In addition to the installation cost, a little
operational expenditure, structure, characteristics, benefits of this
small-scale biogas plant, this article introduces a wide range of
specific popularization methods such as training, financial support,
guided tour to the biogas plant, community-based group study and
delivery of operational manuals. The feasibility of the biogas plant is
explored on the basis of the availability of the raw materials. Simple
operations contained in the current work increase the possibility of
the wide use of this small-scale biogas plant in similar regions of the
world.
Abstract: A horizontal anaerobic digester was developed and
tested in pilot scale for Korean food waste with high water contents
(>80%). The hydrogen sulfide in the biogas was removed by a
biological desulfurization equipment integrated in the horizontal
digester. A mixer of the horizontal digester was designed to easily
remove the sediment in the bottom and scum layers on surface in the
digester. Experimental result for 120 days of operation of the pilot
plant showed a high removal efficiency of 81.2% for organic
substance and high stability during the whole operation period were
acquired. Also food waste was treated at high organic loading rates
over 4 kg•VS/m3∙day and a methane gas production rate of 0.62
m3/kg•VSremoved was accomplished.
The biological desulfurization equipment inside the horizontal
digester was proven to be an economic and effective method to reduce
the biogas desulfurization cost by removing hydrogen sulfide more
than 90% without external desulfurization equipments.
Abstract: In this paper, a Biochemical Methane Potential (BMP)
test provides a measure of the energy production potential from codigestion
between the frozen seafood wastewater and the decanter
cake. The experiments were conducted in laboratory-scale. The
suitable ratio of the frozen seafood wastewater and the decanter cake
was observed in the BMP test. The ratio of the co-digestion between
the frozen seafood wastewater and the decanter cake has impacts on
the biogas production and energy production potential. The best
performance for energy production potential using BMP test
observed from the 180 ml of the frozen seafood wastewater and 10 g
of the decanter cake ratio. This ratio provided the maximum methane
production at 0.351 l CH4/g TCODremoval. The removal efficiencies
are 76.18%, 83.55%, 43.16% and 56.76% at TCOD, SCOD, TS and
VS, respectively. The result can be concluded that the decanter cake
can improve the energy production potential of the frozen seafood
wastewater. The energy provides from co-digestion between frozen
seafood wastewater and decanter cake approximately 19x109
MJ/year in Thailand.
Abstract: BioEnergy is an archetypal appropriate technology
and alternate source of energy in rural areas of China, and can meet
the basic need for cooking fuel in rural areas. The paper introduces
with an alternate mean of research that can accelerate the biogas
energy production. Tithonia diversifolia or the Tree marigold can be
hailed as mesophillic anaerobic digestion to increase the production
of more Bioenergy. Tithonia diversifolia is very native to Mexico and
Central America, which can be served as ornamental plants- green
manure and can prevent soil erosion. Tithonia diversifolia is widely
grown and known to Asia, Africa, America and Australia as well.
Nowadays, Considering China’s geographical condition it is found
that Tithonia diversifolia is widely growing plant in the many tropical
and subtropical regions of southern Yunnan- which can have great
usage in accelerating and increasing the Bioenergy production
technology. The paper discussed aiming at proving possibility that
Tithonia diversifolia can be applied in biogas fermentation and its
biogas production potential, the research carried experiment on
Tithonia diversifolia biogas fermentation under the mesophilic
condition (35 Celsius Degree). The result revealed that Tithonia
diversifolia can be used as biogas fermentative material, and 6%
concentration can get the best biogas production, with the TS biogas
production rate 656mL/g and VS biogas production rate 801mL/g. It
is well addressed that Tithonia diversifolia grows wildly in 53
Counties and 9 cities of Yunnan Province, which mainly grows in
form of the road side plants, the edge of the field, countryside, forest
edge, open space; of which demersum-natures can form dense
monospecific beds -causing serious harm to agricultural production
landforms threatening the ecological system as a potentially harmful
exotic plant. There are also found the three types of invasive daisy
alien plants -Eupatorium adenophorum, Eupatorium Odorata and
Tithonia diversifolia in Yunnan Province of China-among them the
Tithonia diversifolia is responsible for causing serious harm to
agricultural production. In this paper we have designed the
experimental explanation of Biogas energy production that requires
anaerobic environment and some microbes; Tithonia diversifolia
plant has been taken into consideration while carrying experiments
and with successful resulting of generating more BioEnergy
emphasizing on the practical applications of Tithonia diversifolia.
This paper aims at- to find a new mechanism to provide a more
scientific basis for the development of this plant herbicides in Biogas
energy and to improve the utilization throughout the world as well.
Abstract: The aim of this study was to investigate the
effectiveness of anaerobic digestion for the treatment of wool
scouring wastes. The experiments design comprised three ratios of
waste (W) to seed(S) (W:S) of 25:75, 50:50 and 75:25, corresponding
to 1.9. 1.7 and 1.5g tCOD/g TS, respectively, with or without
chemicals addition. NH4Cl was added to the reactors as a source for
nitrogen to achieve C:N:P of 420:14:3. A cationic flocculent was
added at 0.5 and 0.75% to enhance flocculation of sludge. The results
showed that the reactors that received W:S at a ratio of 25:75
produced the largest volume of biogas. The final soluble COD
(sCOD) was below the limits for discharge to the sewer system.
Abstract: This paper presents the results of the preliminary investigation of microwave (MW) irradiation pretreatments on the anaerobic digestion of food residues using biochemical methane potential (BMP) assays. Low solids systems with a total solids (TS) content ranging from 5.0-10.0% were analyzed. The inoculum to bulk mass of substrates to water ratio was 1:2:2 (mass basis). The experimental conditions for pretreatments were as follows: a control (no MW irradiation), two runs with MW irradiation for 15 and 30 minutes at 320 W, and another two runs with MW irradiation at 528 W for 30 and 60 minutes. The cumulative biogas production were 6.3 L and 8.7 L for 15min/320 W and 30min/320 W MW irradiation conditions, respectively, and 10.5 L and 11.4 L biogas for 30min/528 W and 60min/528 W, respectively, as compared to the control giving 5.8 L biogas. Both an increase in exposure time of irradiation and power of MW had increased the rate and yield of biogas. Singlefactor ANOVA tests (p
Abstract: The consumption of lactose in acid cheese whey
anaerobic fermentation process under fed-batch conditions was
studied. During fermentation for 100 hours the biogas production
(CO2 and CH4) was analyzed online. Among the standard analyses
FT-IR spectroscopy was used to follow the consumption of lactose by
bacteria. The absorption bands at 990, 894 and 787 cm-1 in the 2nd
derivative spectra were shown to be characteristic for lactose and
were used to follow the lactose conversion. It was shown that acid
cheese whey lactose was converted by bacteria in first 7 hours. In the
spectra of 17, 18 and 95 hour fermentation samples lactose was not
identified and these results correlated with the HPLC data.
Abstract: The potential, opportunities and drawbacks of biogas
technology use in Turkey are evaluated in this paper. Turkey is
dependent on foreign sources of energy. Therefore, use of biogas
technology would provide a safe way of waste disposal and recovery
of renewable energy, particularly from a sustainable domestic source,
which is less unlikely to be influenced by international price or
political fluctuations. Use of biogas technology would especially
meet the cooking, heating and electricity demand in rural areas and
protect the environment, additionally creating new job opportunities
and improving social-economical conditions.
Abstract: The daily increase of organic waste materials resulting
from different activities in the country is one of the main factors for
the pollution of environment. Today, with regard to the low level of
the output of using traditional methods, the high cost of disposal
waste materials and environmental pollutions, the use of modern
methods such as anaerobic digestion for the production of biogas has
been prevailing. The collected biogas from the process of anaerobic
digestion, as a renewable energy source similar to natural gas but
with a less methane and heating value is usable. Today, with the help
of technologies of filtration and proper preparation, access to biogas
with features fully similar to natural gas has become possible. At
present biogas is one of the main sources of supplying electrical and
thermal energy and also an appropriate option to be used in four
stroke engine, diesel engine, sterling engine, gas turbine, gas micro
turbine and fuel cell to produce electricity. The use of biogas for
different reasons which returns to socio-economic and environmental
advantages has been noticed in CHP for the production of energy in
the world. The production of biogas from the technology of anaerobic
digestion and its application in CHP power plants in Iran can not only
supply part of the energy demands in the country, but it can
materialize moving in line with the sustainable development. In this
article, the necessity of the development of CHP plants with biogas
fuels in the country will be dealt based on studies performed from the
economic, environmental and social aspects. Also to prove the
importance of the establishment of these kinds of power plants from
the economic point of view, necessary calculations has been done as
a case study for a CHP power plant with a biogas fuel.
Abstract: The effects of upflow liquid velocity (ULV) on
performance of expanded granular sludge bed (EGSB) system were
investigated. The EGSB reactor, made from galvanized steel pipe
0.10 m diameter and 5 m height, had been used to treat piggery
wastewater, after passing through acidification tank. It consisted of
39.3 l working volume in reaction zone and 122 l working volume in
sedimentation zone, at the upper part. The reactor was seeded with
anaerobically digested sludge and operated at the ULVs of 4, 8, 12
and 16 m/h, consecutively, corresponding to organic loading rates of
9.6 – 13.0 kg COD/ (m3.d). The average COD concentrations in the
influent were 9,601 – 13,050 mg/l. The COD removal was not
significantly different, i.e. 93.0% - 94.0%, except at ULV 12 m/h where
SS in the influent was exceptionally high so that VSS washout had
occurred, leading to low COD removal. The FCOD and VFA
concentrations in the effluent of all experiments were not much
different, indicating the same range of treatment performance. The
biogas production decreased at higher ULV and ULV of 4 m/h is
suggested as design criterion for EGSB system.
Abstract: In this study, the effects of biogas fuels on the performance of an annular micro gas turbine (MGT) were assessed experimentally and numerically. In the experiments, the proposed MGT system was operated successfully under each test condition; minimum composition to the fuel with the biogas was roughly 50% CH4 with 50% CO2. The power output was around 170W at 85,000 RPM as 90% CH4 with 10% CO2 was used and 70W at 65,000 RPM as 70% CH4 with 30% CO2 was used. When a critical limit of 60% CH4 was reached, the power output was extremely low. Furthermore, the theoretical Brayton cycle efficiency and electric efficiency of the MGT were calculated as 23% and 10%, respectively. Following the experiments, the measured data helped us identify the parameters of dynamic model in numerical simulation. Additionally, a numerical analysis of re-designed combustion chamber showed that the performance of MGT could be improved by raising the temperature at turbine inlet. This study presents a novel distributed power supply system that can utilize renewable biogas. The completed micro biogas power supply system is small, low cost, easy to maintain and suited to household use.
Abstract: Pretreatment of oil palm empty fruit bunch (OPEFB) with N-Methylmorpholine-N-oxide (NMMO) to enhance biogas production was investigated. The pretreatments were performed at 90 and 120ºC for 1, 3, and 5 h using three different concentrations of NMMO of 73%, 79%, and 85%. The pretreated OPEFB was subsequently anaerobically digested to produce biogas. After pretreatment, there were no significant changes of the main composition of OPEFB and the maximum total solid recovery was 92%. The amorphous phase was increased up to 78% at pretreatment condition using 85% NMMO solution for 3 h at 120oC. In general, higher concentration of NMMO and higher temperature resulted in increased amorphous form and higher biogas production. The best results of biogas production reached enhancement of methane yield of 148% compared to the untreated OPEFB and increased in digestion of 94% compared to starch as reference.
Abstract: Decentralized eco-sanitation system is a promising and sustainable mode comparing to the century-old centralized conventional sanitation system. The decentralized concept relies on an environmentally and economically sound management of water, nutrient and energy fluxes. Source-separation systems for urban waste management collect different solid waste and wastewater streams separately to facilitate the recovery of valuable resources from wastewater (energy, nutrients). A resource recovery centre constituted for 20,000 people will act as the functional unit for the treatment of urban waste of a high-density population community, like Singapore. The decentralized system includes urine treatment, faeces and food waste co-digestion, and horticultural waste and organic fraction of municipal solid waste treatment in composting plants. A design model is developed to estimate the input and output in terms of materials and energy. The inputs of urine (yellow water, YW) and faeces (brown water, BW) are calculated by considering the daily mean production of urine and faeces by humans and the water consumption of no-mix vacuum toilet (0.2 and 1 L flushing water for urine and faeces, respectively). The food waste (FW) production is estimated to be 150 g wet weight/person/day. The YW is collected and discharged by gravity into tank. It was found that two days are required for urine hydrolysis and struvite precipitation. The maximum nitrogen (N) and phosphorus (P) recovery are 150-266 kg/day and 20-70 kg/day, respectively. In contrast, BW and FW are mixed for co-digestion in a thermophilic acidification tank and later a decentralized/centralized methanogenic reactor is used for biogas production. It is determined that 6.16-15.67 m3/h methane is produced which is equivalent to 0.07-0.19 kWh/ca/day. The digestion residues are treated with horticultural waste and organic fraction of municipal waste in co-composting plants.