Biogas Residue Research Articles

Effect of Serratia sp. K3 combined with organic materials on cadmium migration in soil-vetiveria zizanioides L. system and bacterial community in contaminated soil.

Phytoremediation is an economical strategy to harvest cadmium (Cd) from contaminated soil, but the efficiency of phytoremediation was affected by many factors. This study investigated the potential of Serratia sp. K3 (K3) assisted with straw biogas residue (SBR) or leavening fertilizer (LF) on improving the Cd migration efficiency and micro-environment in soil-vetiveria zizanioides L. system. The results showed that the acid soluble Cd in soil was increased by 2.83-29.79% in treatments compared with control (CK). In addition, Cd accumulation in the roots and shoots of vetiveria zizanioides were significantly enhanced by the combination of K3 and SBR/LF. Especially, the translocation factor of Cd increased by 21.53-62.37% in groups with K3 compared with the groups without K3, correspondingly. Furthermore, SBR/LF effectively changed bacterial community structure, and improved bacterial abundance. Relative abundance of functional genes related with carbohydrate/energy/amino acid metabolism were increased in groups of SBRB/LFB rhizosphere compared with CK. These results provide insight into the change of phytoremediation efficiency and soil bacterial communities in the vetiveria zizanioides rhizosphere after inoculation. This study may provide a promising method for improving phytoremediation in Cd contaminated soil.

Effects of Sugarcane Leaves on the Aerobic Composting of Biogas Residue

Effects of Sugarcane Leaves on the Aerobic Composting of Biogas Residue

One-step synthesis of easily-recoverable carboxylated biogas residues for efficient removal of heavy metal ions from synthetic wastewater

Abstract Simultaneous treatment of organic solid waste and heavy metal polluted water has drawn public attention, which can reuse solid waste resource and purify water body. However, regeneration efficiency and production cost limited the wide application of traditional biosorbents in practice. Herein, a recoverable and cost-efficient carboxymethylated biosorbent, named as CA-BR, was synthesized from biogas residues by an easy one-step method. The morphology properties of the CA-BR indicated that this novel biosorbent had a well-developed pore structure with abundant carboxyl functional groups, which contributed to the diffusion and chelation of heavy metal ions. Cu2+ uptake by CA-BR increased with the rising temperature, and the maximum adsorption capability was 76.92 mg/g. The preferential Cu2+ capture by CA-BR can also be achieved in the presence of co-existing cations (K+ and Na+, 200 mg/L), and adsorption capacity could still keep more than 67.69 mg/g. The CA-BR exhibited a good chemical stability and its adsorption capacity could still reach up to 92% after 8 continuous adsorption-desorption cycles, which indicated the feasibility of CA-BR in real applications. Furthermore, the treatment volumes of synthetic wastewater were 550 mL (275 BV) for Cu2+ (using 1 g of CA-BR), and several column adsorption-desorption cycles exhibited that there was no significant loss in Cu2+ capacity (

Mesoporous Activated Biochar for As(III) Adsorption: A New Utilization Approach for Biogas Residue

To develop a new utilization approach of biogas residues, mesoporous activated biochar (MB) was prepared from biogas residues and used for adsorption of As(III) from aqueous solution. MB-ZnCl2-600,...

Modified biogas residues as an eco-friendly and easily-recoverable biosorbent for nitrate and phosphate removals from surface water

Effective managements of organic solid waste and surface water eutrophication can reuse/reduce solid waste resources, and ensure surface water safety. Herein, an easily-recoverable amine-functionalized biosorbent was developed from biogas residue (BR-N) for nitrate and phosphate removals from surface water. Physicochemical characteristics revealed that BR-N has a cross-staggered structure with abundant quaternary-amine groups to enhance the diffusion and electrostatic attraction of nitrate/phosphate. In batch studies, nitrate/phosphate could be effectively removed by the BR-N within a wide pH range of 5.0–9.0, and the maximum adsorption capacities of BR-N were 64.12 mg/g for nitrate and 34.40 mg P/g for phosphate. After continuous 8 cycles of adsorption-desorption, BR-N still exhibited >82% adsorption capacity for nitrate/phosphate removals, implying the high chemical stability and reusability for water treatment. Whereafter, BR-N has real application prospect in water treatment, which could effectively treat ˜380, ˜260 and ˜760 bed volumes (BV) of three actual eutrophic surface water to satisfy the surface water standard of China (GB3838-2002). The cost of BR-N was 2.89 $/kg evaluated by energy-economy assessment, indicating the low-cost production of biogas residue-based adsorbent for treating eutrophic surface water. Overall, this study provides a new idea for high-value utilization of organic solid waste and purification of eutrophic water.

Co-hydrothermal carbonization of digested sewage sludge and cow dung biogas residue: Investigation of the reaction characteristics

In order to recovery energy from digested sewage sludge (DSS) and cow dung biogas residue (CDBR), co-hydrothermal carbonization (co-HTC) was employed to obtain the hydrochar for the use as solid fuel. Carbon content and higher heating value of hydrochars were increased, while the O/C and H/C atomic ratios reduced, revealing the dominance of the dehydration reaction during the co-HTC of DSS and CDBR. The interaction between DSS and CDBR or their derivate intermediates took place during the co-HTC for the TOC value exceeded far more than that in the raw materials and the intensity of mixture was lower than pure material. The CDBR can notably promote hydrochar formation during the co-HTC with DSS, resulting in a high fraction of nitrogen content in hydrochar of DSS. The combustion properties of hydrochar were improved notably when CDBR was added, evidencing by the increasing ignition temperature and the comprehensive devolatilization index. The activation energy of the hydrochar from co-HTC increased notably especially the hydrochar with 75% CDBR. This study suggested that co-HTC of the mixed feedstocks was a promising strategy to prepare a high-quality hydrochar for recovery energy.

Linking bacterial community to aggregate fractions with organic amendments in a sandy soil

AbstractSoil aggregates provide microhabitats for microorganisms. However, the bacterial communities within various aggregate size fractions under organic amendments have rarely been evaluated especially in sandy soils. A field experiment involving addition of biogas residue (BR), pig manure (PM), biochar (BC), and straw (ST) of a sandy soil was performed to determine the structure of the bacterial community in aggregate size fractions by using high‐throughput sequencing. We found that organic amendments change soil aggregate fractions and nutrient content, alter bacterial diversity and composition, and contribute to the predicted bacterial functions. The BR increased bacterial α‐diversity in <0.25‐mm aggregates. The Nitrospirae was abundant in almost all aggregate sizes, whereas the abundance of Actinobacteria decreased in most of aggregates following BR addition. The PM amendment primarily facilitated the growth of Bacteroidetes and inhibited the growth of Acidobacteria and Chloroflexi in 0.25‐ to 2‐mm aggregates, whereas bacterial α‐diversity was decreased in the >0.25‐mm aggregates. The BC treatment decreased the bacterial α‐diversity in the <0.25‐mm aggregates and the Gemmatimonadetes abundance in all <2‐mm aggregates, but the Actinobacteria abundance was significantly increased in the >0.053‐mm aggregates. Collectively, the effects of organic amendments on the bacterial community varied greatly depending on type of amendments and aggregate size. The BR supported highly diverse bacterial taxa in the <0.25‐mm aggregates, whereas it proliferated N cycling‐related bacteria in all aggregates. Our results highlight the links between bacterial community and aggregate size fractions in sandy soils depending on organic amendments.

Exergy analyses of biogas production from microalgae biomass via anaerobic digestion

Biogas production from microalgae biomass without pretreatment and with hydrothermal pretreatment involve the energy with different quality and quantity, which makes it complex to evaluate thermodynamic performance. In this paper, exergy analyses were conducted in biogas production from microalgae biomass without pretreatment, with hydrothermal pretreatment, and with solar-driven hydrothermal pretreatment. The results showed that the materials and energy flow affected exergy efficiency in biogas production from microalgae biomass. The biogas production from microalgae biomass with solar-driven hydrothermal pretreatment achieved the highest exergy efficiency (40.85%), compared with that without pretreatment (26.2%) and with hydrothermal pretreatment (35.98%). In addition, the maximum exergy loss was caused by biogas residue, which accounted for 60.58%, 38.54%, and 35.13% of overall exergy input in biogas production from microalgae biomass without pretreatment, with hydrothermal pretreatment, and with solar-driven hydrothermal pretreatment, respectively. Exergy analyses provide important theoretical guidance to improve the performance of biogas production from microalgae biomass.

Converting CO2 from biogas and MgCl2 residues into valuable magnesium carbonate: A novel strategy for renewable energy production

In this work a novel strategy for bio-methane production and magnesium chloride waste valorization is addressed. The proposed process is a potential alternative path to the already existing biogas upgrading technologies by carbon dioxide mineralization into valuable magnesium carbonate. The main parameters affecting the precipitation efficiency (reaction time, reaction temperature, and molar ratio reactant/precipitator) are studied, leading to promising results which spark further investigation in this innovative route. Additionally the purity and the morphology of the obtained solid product was accurately analysed through different physicochemical characterization techniques such as Raman, X-Ray diffraction and Scanning electron microscope. The characterisation study reveals a mixture of Nesqueonite and Dypingite carbonate phases obtained in the process being the later the dominant phase in the resulting precipitate. Overall, the results discussed herein confirmed the technical feasibility of this innovative strategy for synergizing carbon dioxide mineralization and renewable energy production.

Feasibility of anaerobic digestion on the release of biogas and heavy metals from rice straw pretreated with sodium hydroxide.

The feasibility of anaerobic digestion on the release of biogas and heavy metals from contaminated rice straw pretreated with NaOH solution was studied. The results show that NaOH pretreatment can significantly boost the release of biogas and heavy metals from rice straw using anaerobic digestion. Under the optimal conditions for biomass pretreated 6% (w/w) NaOH with a solid-to-solution ratio of 1:20, total biogas and methane yields of 446.3 mL/g and 263.5 mL/g volatile solids were achieved, which were 22.18% and 41.59% higher than those of the control without NaOH pretreatment, respectively, and the release percentages of Cd, Pb, Cu, and Zn from rice straw reached 86.95-97.69%. The release of heavy metals from rice straw can contribute to both the degradation of lignin by NaOH pretreatment and the utilization/transformation of lignocellulose via anaerobic digestion. The acidification levels and total volatile fatty acid contents significantly influence on the release of heavy metals. Based on the Illumina HiSeq sequencing analysis, the dominant phyla in the biogas residues were proteolytic (Bacteroidetes) and hydrogen-producing (Firmicutes) bacteria, while the growth of Methanospirillum and Methanosaeta in anaerobically digested effluent was promoted. The results revealed that anaerobic digestion combined with NaOH pretreatment is suitable for the disposal of heavy metal-contaminated biomass.

Characteristics of Phosphorus Adsorption in Aqueous Solution By Ca/Mg-Loaded Biogas Residue Biochar

In this study, we synthesized Ca/Mg biochar sorbents (CMZZs) by pyrolysis of biogas residue (ZZs) impregnated with calcium chloride and magnesium chloride and investigated their potential to adsorb P from water. The results showed that the content of calcium and magnesium in the modified biochar was 1.3 and 15.4 times, respectively, what they were before the modification. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) patterns showed that the type of chemical functional groups on the surface of biochar had not changed, but several new peaks appeared, indicating that Mg (OH)2 and MgO might be present on the surface of the CMZZs. The biochar equilibrium data were well described by the Freundlich model, and the adsorption reached equilibrium after 100 min. The adsorption kinetics followed a pseudo-second-order model, and the maximum adsorption capacity of the CMZZs was 76.92 mg·g-1 when the pH was 9 and the temperature 303 K. The results revealed that a soaking method can effectively load Ca2+ and Mg2+ onto the surface of ZZ, and CMZZs offer a promising adsorbent for P removal with a high adsorption capacity for P from wastewater.

Biogas residues in substitution for chemical fertilizers: A comparative study on a grassland in the Walloon Region

To provide sufficient quantities of food and feed, farming systems have to overcome limiting factors such as the nutrient depletion of arable soils. Nitrogen being the main mineral element required for plant growth, has led to the extensive use of chemical fertilizers causing nitrogen pollution of the ecosystems. This field study investigates the use of biogas residues (BRs) as biofertilizers and their contribution to the mitigation of nitrate leaching in agricultural soils, while also demonstrating the polluting nature of chemical fertilizers. Nine different fertilization treatments classified in three schemes and two nitrogen doses were tested for three consecutive years on a grassland in the Walloon Region of Belgium. Residual soil mineral nitrogen, percentage contribution of treatments in residual nitrate and agronomic performance were assessed for each fertilization treatment. The results obtained showed significant differences on treatment and scheme level regarding nitrate accumulation in the soil, with chemical fertilizers posing the highest nitrate leaching risk. BRs did not cause nitrate accumulation in the soil, and were N rate and rainfall independent, while the chemical treatments indicated a cumulative tendency under high N rate and low precipitation. Forage yield did not demonstrate statistical differences on treatment and scheme level but varied with changing precipitation, while the maximum application rate suggested a plateau. Aboveground nitrogen content was significantly higher after the application of chemical fertilizers only in the first year, while all the chemical treatments indicated a dilution effect under elevated annual rainfall. Finally, the partial substitution of chemical fertilizers by raw digestate reduced the concentration of NO3− in the soil without having a negative impact on the yield and N content of the biomass. These results strongly advocate for the environmental benefits of BRs over chemical fertilizers and underline their suitability as biofertilizers and substitutes for chemical fertilizers in similar agricultural systems.

RANCANG BANGUN REAKTOR BIOGAS SKALA RUMAH TANGGA

Inadequate disposal of livestock manure has caused environmental pollution around the village, both water, soil and air (smell). Animal waste in the form of liquid is deliberately flowed into the river while solid waste is left piled up around the cage. The occurrence of odor and pollution is sometimes triggered social conflict, with complaints from local communities. With a population of 35 head of cattle for a farmer group, assuming the average per cow yields 15 kg of solid waste, the waste produced can reach approximately 525 kg per day. The lack of knowledge and the low educational background of the cattle ranchers in the Arabica Village makes the awareness of the environment to be lacking, as well as the technology of processing animal waste and the benefits. Biogas Reaktors of animal waste, although they have heard but lack of knowledge of how to make biogas installations and the assumption that the budget is spent to build the technology makes them prefer to allocate these funds to other things in order for the survival of livestock business can be sustainable. By looking at the existing potential, of course, if managed properly, Arabica Village can become an energy independent village and is a new business opportunity, for biogas products and residues from the installation of biogas in the form of organic fertilizer.

Effects of biogas residues containing antibiotics on soil enzyme activity and lettuce growth.

To investigate the effects of biogas residues containing antibiotics on lettuce growth and soil enzyme activity, the antibiotics oxytetracycline and sulfadiazine were used as additives; two kinds of feedstocks including pig manure and straw were chosen. Results showed that the higher the concentrations of the antibiotics are, the stronger the inhibition of soil sucrase activity becomes. The activity of sucrose enzyme in the test group with a single concentration of 60mg/kg was significantly lower than the group that was treated with 0mg/kg. In the mass, the organic fertilizer containing antibiotics can improve the soil urease activity and increase the urease activity of the soil. In the growth phase, urease activity increased by 27% from 0.85mg NH3-N/(gday) in the blank group to 1.08 NH3-N/(gday) in the 0-mg test group. During all growing stages of lettuce, though the effects of the biogas residues containing oxytetracycline and sulfadiazine on the soil catalase activity were not obvious, the field application could inhibit the activity of soil catalase to some extent.

Characteristics of leaching agents for heavy metal extraction and safe utilisation of pig farm biogas residues

The continuous development of biogas engineering in recent years has been accompanied by an increasing number of biogas-residue types in the environment. The existence of various heavy metal elements in biogas residues, particularly excessive amounts of zinc and copper in pig farm biogas residues, hinders their safe utilisation. Several studies have focused on an effective composition for biogas residues or on their effects on soil and plants. However, few investigations regarding the removal of harmful substances from biogas residues have been conducted. The characteristics of heavy metals leached from pig farm biogas residues using eight types of leaching agents were analysed in this study. It is expected that, based on this study, different uses for biogas residues can be developed under the premise of security. The results showed that the most suitable extractant of heavy metals from pig farm biogas residues was EDTA2Na. The leaching rates increased over time. The leaching rates of copper and zinc after 2 h were 21.91% and 48.66%, respectively. After being leached for 2 h by EDTA-2Na, the concentration of zinc met the requirements for moderate alkaline soil, according to the Control Limits against Harmful Substances in Composts for Agricultural Use (DB44/T 361-2006) standard.

Co-composting of the biogas residues and spent mushroom substrate: Physicochemical properties and maturity assessment

Recycling of BR and SMS are crucial for the development of biogas industry and commercial mushroom cultivation. The seed germination test is limited to examine the maturity of compost because of lacking the effect of insoluble part on plant growth. The aim of this study was to evaluate the maturity of compost by analysis the relationship between agronomic parameters of plant growth with physicochemical parameters of compost. The thermophilic period (over 50 °C) was lasted 52 days. TOC, C/N, AP and NH4+-N was decreased along with composting process, while TK, TP, AK and NO3−-N showed an opposite trend. As for seedling quality, the raw material (T0) showed the worst plant growth but the 100% compost (T1) showed better seedling quality compared with commercial seedlings. According to the analysis of Spearman correlation, the results indicated that TOC, C/N, NH4+-N, NO3−-N, AK and lignocellulose can be used to evaluate compost maturity.

Properties of Biochar from Anaerobically Digested Food Waste and Its Potential Use in Phosphorus Recovery and Soil Amendment

The disposal of a large amount of biogas residue from anaerobically digested food waste is a burden for biogas production. The aim of this work was to investigate biogas residue as a potential feedstock, by preparing biochar at a broad pyrolysis temperature range of 400–900 °C. The properties required for phosphorus recovery and soil amendment application were evaluated. Biogas residue collected from an urban food waste treatment plant was pyrolyzed in a laboratory scale reactor. It was found that by increasing the pyrolysis temperature, the yield of biochar decreased and the pH, electrical conductivity and Brunauer–Emmett–Teller surface area increased. The amount of phosphorus adsorbed onto the biogas residue-derived biochar (BRB) at 900 °C was larger than that of other kinds of biochar. The kinetics of phosphorus (P) adsorption on BRB could be described by the pseudo-second-order equation. The pot experiments showed that the resulting biochar is beneficial for the growth of cabbage. Overall, turning solid residue from the anaerobic digestion of food waste for biogas production into biochar shows good prospects as a means of solving the disposal problem, while creating new markets for food waste biogas residue.

Water-stable aggregates and carbon accumulation in barren sandy soil depend on organic amendment method: A three-year field study

Organic amendment has proven to reduce resource waste and environmental pollution, in addition to increasing soil quality. However, the effect of different organic amendment methods on water-stable aggregates and soil organic carbon (SOC) accumulation is unknown, especially in barren sandy soil. A field experiment with four organic amendment methods, straw (ST, local practice), biogas residue (BR), manure (PM), and biochar (BC), was designed with the equal amount of nitrogen (N) input in the North China Plain. Soil aggregate distribution, stability, and aggregate-associated C at two depths (0–10 cm and 10–20 cm) were analyzed after a treatment was applied to evaluate soil quality improvement. The main results were as follows: compared to ST treatment, BC treatment enhanced SOC in the 0–10 cm and 10–20 cm layers by 143.8% and 156.5%, respectively (P < 0.05). The mean weight diameter (MWD) of soil aggregates in BR, PM, and BC treatments decreased by 16.2%–31.8%, 10.0%–24.7% (except the 2015 0–10 cm layer), and 18.9%–43.2% compared with ST treatment from 2014 to 2016. BC treatment increased C concentrations in all aggregate fractions compared to ST treatment in 2015–2016 (P < 0.05). The correlations between soil microbial biomass C and MWD (R = 0.7185, P < 0.001) and dissolved organic C and MWD (R = 0.5600, P < 0.001) indicated that soil aggregation is mainly affected by labile organic C in barren sandy soil. All four types of organic amendments increased SOC content; additionally, ST amendment had the highest capacity for aggregate formation. The results indicated that ST amendment is more appropriate for barren sandy soil than BR, PM or BC amendments, and improves soil quality for sustainable soil management.

Bioconversion of Mixed Fruit Waste as a Potential Source of Biogas and Organic Fertilizer

This paper investigates the bioconversion of mixed fruit waste as a potential source of biogas and organic fertilizer. The pH of digester liquid, influent and effluent, temperature of gas production volume were observed. In addition to this, TS and VS of the manure before and after digestion were determined. The TS/VS lost in fermenter and efficiencies of VS conversion to gas was also monitored at the end of the study. The study also shows that residue left after the production of biogas is a valuable organic fertilizer that can be used as an alternative to inorganic fertilizer in maize production and soil fertility. Yield of maize was significantly increased over that of the control. Markedly influenced by the application of organo-minerals, NPK fertilizer and their combination as observed from the increased plant height, diameter of plant stem, leaf area and Weight of 1000 kernels compared to the control. Biogas residue has therefore proved to be environmentally friendly and an effective fertilizer. The use of locally available, nutrient rich organic sources is an effective means for improving soil fertility and increasing crop yield in view of the escalating cost of inorganic fertilizers and low fertilizer use efficiency of crops.

Recovery of phosphate from piggery biogas slurry by ultrasonication, aeration and addition of MgO desulfurization waste residue

The traditional phosphorus recovery process for piggery wastewater has not utilized the large amount of phosphorus in the biogas residue, resulting in a low phosphorus recovery percentage. This study uses an ultrasonic pretreatment step to release phosphorus from the biogas residue using magnesium oxide desulfurization waste residue (MDWR) as a low-cost magnesium source. CO2 is removed by aeration stripping to increase the pH of the system. The results showed that when the ultrasonication time was 80 min and the ultrasonic energy density was 1000 W·L−1, the phosphorus release was increased by 109.31%. Using an MDWR addition amount of 0.8 g·L−1, initial pH of 9.5, and aeration time of 2 h, the recovery percentage of PO43--P was 98.90%, the best recovery effect. The analysis shows that the recovered product is mainly struvite. The ultrasonic and aeration/MDWR addition combination process is thus considered to be a promising technology.