Highest Biochemical Methane Potential Research Articles

Biochemical methane potentials in co-digestion of whey, macroalgae and cattle sludge at different mixture rates

In this study, cattle sludge, algae and cheese whey were mixed at 3 different ratios and co- digested under laboratory conditions at 4 different digestion temperatures in order to determine biochemical methane potentials. In addition, for comparison purposes with mixtures, cattle sludge alone was subjected to biogas treatment. The experimental setup designed and manufactured for this purpose. The highest biochemical methane potential (BMP) was obtained in the Mixture-2 which contains 30% cattle sludge, 20% algae and 50% cheese whey with 0,345 Nm3 CH4/kgVS at 45 ºC temperature. As the ratio of cheese whey in the mixtures and digestion temperature increased, the biochemical methane potential also increased. BMP of cattle sludge was less than that of all mixtures.

Impact of using glucose as a sole carbon source to analyze the effect of biochar on the kinetics of biomethane production

The adaptation of biochar in anaerobic digestion (AD) positively influences the conversion of substrate to biomethane and promotes system stability. This study investigated the influence of biochar (BC) doses (0 to 8 g/L) on the Biochemical Methane Potential (BMP) of glucose during a 60-day AD in a mesophilic batch-type reactor. The first 6.5 weeks of the experimentation were dedicated to the microorganism’s adaptation to the biochar and degradation of organics from the used inoculum (3 phases of the glucose feeding). The last 2 weeks (4th phase of glucose feeding) represented the assumption, that glucose is the sole carbon source in the system. A machine learning model based on the autoregressive integrated moving average (ARIMA) method was used to model the cumulative BMP. The results showed that the BMP increased with the amount of BC added. The highest BMP was obtained at a dose of 8 g/L, with a maximum cumulative BMP of 390.33 mL CH4/g-VS added. Likewise, the system showed stability in the pH (7.17 to 8.17). In contrast, non-amended reactors produced only 135.06 mL CH4/g-VS and became acidic at the end of the operation. Reducing the influence of carbon from inoculum, sharpened the positive effect of BC on the kinetics of biomethane production from glucose.

Anaerobic Co-Digestion of Vinasse and Pentose Liquor and the Role of Micronutrients in Methane Production within Sugarcane Biorefineries

Anaerobic digestion (AD) of residues from integrated first- and second-generation ethanol (1G2G) biorefineries is a sustainable method for energy recovery through biogas production. This study evaluated the co-digestion of 1G vinasse, 2G vinasse and pentose liquor (from the pretreatment of sugarcane bagasse for 2G ethanol production) compared to individual digestions using biochemical methane potential (BMP) assays. The results showed some “key” micronutrients from the substrates that affected methane (CH4) production, while their balance provided by co-digestion achieved high digestibility (95%). High iron (Fe) and nickel (Ni) concentrations, in addition to furfural (0.33 g L−1) in pentose liquor seemed to decrease its CH4 production potential. Despite these adverse effects observed in mono-digestion, co-digestion was beneficial for this substrate, increasing digestibility (52%) and BMP (118%). The highest BMP was observed in vinasse 2G (631 ± 6 NmL CH4 gTVS−1), with no significant difference compared to the adjusted modified Gompertz model (624 ± 10 NmL CH4 gTVS−1). The co-digestion system also presented the highest specific CH4 production rate (20 ± 1 NmL CH4 gTVS−1day−1) and shortened the lag phase by 19% compared to the AD of isolated 1G vinasse with the second lowest BMP value (494 ± 11 NmL CH4 gTVS−1).

Greenhouse Residues’ Potential for Biogas Production

Agricultural residues are intensively evaluated as potential feedstocks for biogas plants. Vegetable crops generate massive residues during and at the end of their growing seasons. A greenhouse facility in Greece, Thrace Greenhouses S.A., generates 7000–8000 t per year of residual green biomass, resulting from the hydroponic cultivation of tomatoes and cucumbers on 170,000 m2 of land from February to November. The crop residues included leaves, suckers, and stalks. The biochemical methane potential (BMP) estimation was realized on samples taken in March, May, and August, as well as at the end of cultivation (November). Suckers, leaves, and stalks of both plants yielded a range of 221–357, 210–296, and 225–250 NL kg−1 VS, respectively. t-test statistical analysis showed that the BMP of the leaves and suckers were statistically different for tomato and cucumber plants. The BMP of stalks was lower than the other residue types except for the tomato leaves. The diauxic behavior of the specifi‘1c methane production curves indicated that the two-phase Gompertz model (TGM) was the most suitable. The model fitting showed that leaves and suckers, in spite of having a higher BMP than the stalks, exhibited a lower maximum specific methane production rate constant than the stalks during the first phase, which may indicate the presence of inhibitory or slowly biodegradable compounds in leaves and suckers in comparison to the stalks.

Giant reed from wetlands as a potential resource for biomethane production

This study aimed to evaluate the potential and the use of the natural and treatment wetland biomass for local energy production. Specifically, it was addressed by determining the giant reed (Arundo donax L.) Biochemical Methane Potential at different harvest times, since plant characteristics vary noticeably along the growing season. In the last decades, this perennial rhizomatous grass has achieved great success in the renewable energy market to produce biogas through the anaerobic digestion process, because is a non-food crop with high biomass yield (about 35 Mg dry matter per hectare) and low input required for its growth. Several studies showed that the harvest time, in relation to the stage of the plant development, significantly affect the Biochemical Methane Potential. Moreover, it is well known that giant reed presents feature comparable in terms of biomass yield and physicochemical composition both in natural and treatment wetland systems. Anaerobic digestion laboratory tests were carried out to assess biomethane production from aerial biomass samples collected from July to November 2021. The average biogas production for the five different harvest times was of 312.77 Nm3/tVS (±62.87), and the mean methane content was equal to 187.06 Nm3 CH4/tVS (±38.32). The gas quality at the end of the Biochemical Methane Potential test displayed average contents of methane of 58.88% (±5.06) and CO2 of 18.54% (±7.91) and mean sulfides content of 112.10 ppm (±103.61). The results highlighted that giant reed has a high energy returned on energy invested (EROEI) value. The research activity allowed to identify the harvest time associated with the highest Biochemical Methane Potential and biomethane production per hectare. Finally, the experimental results achieved in riverbank conditions could be applied to treatment wetland systems increasing their environmental sustainability and reducing their maintenance costs.

Optimizing the Biochemical Methane Potential (BMP) of Food Waste

Recent advances in anaerobic digestion has resulted in expansion of sustainable methods for use of waste as energy resources. Conventional methods prove to be uneconomical and environmentally impractical. Moreover, the microbial consortia in anaerobic digestion are temperature dependent and therefore requires investigations on temperature optimization. Therefore, the recent experimental study is being undertaken with the objective in order to assess the effect of temperature on anaerobic biodegradation of food wasted from a hostel campus. The effect of temperature on methane generation rate has also been investigated. The anaerobic digestion study under psychrophilic, mesophilic and thermophilic temperature conditions has been carried out and compared in order to assess the optimum methane production conditions. All the experimental study for anaerobic digestion of food waste has been carried out at optimum F/M (food to mass) ratio of 0.75. The cumulative highest methane production is observed to be 33, 50 and 65 mL of CH4 in reactor R1, R2 and R3 with initial food waste COD dosage of 100, 150 and 200 mg, respectively under mesophilic temperature conditions. The highest biochemical methane potential (BMP) value of 0.94, 0.95 and 0.93 gCH4-COD/gCOD fed in reactor R1, R2 and R3 respectively, under mesophilic temperature conditions. It been observed that for maximum methane generation rate constant of 0.62 d-1 were observed under thermophilic conditions thus has to be highly accelerative process but overall conversion of organic matter to methane is less as compared to mesophilic temperature conditions, this is because free ammonia concentration increases with increasing temperature, by influencing the equilibrium. However, mesophilic conditions provide a more stable environment for the anaerobic digestion process. This may be due to the fact that temperature fluctuations can disrupt the microbial activity and slow down the process, but mesophilic conditions provide a stable environment for the microorganisms to thrive. Therefore, the mesophilic temperature range provides a balance between high reaction rates, stability, and cost-effectiveness, making it the optimal temperature range for anaerobic digestion of food waste. The obtained results in present study will be helpful in implementing on full-scale anaerobic solid waste digesters for enhancing the methane generation under mesophilic temperature conditions with high organic matter removal. Also, under thermophilic conditions the energy requirement for heating proves to be uneconomical.

Pilot Study on Predictive Traits of Fresh Maize Hybrids for Estimating Milk and Biogas Production

Farmers need information on which maize hybrid is best and under what conditions. They demand that this information be clear, simple and easily understood. This study aims to estimate the potential for milk production (MPP) and the biochemical methane potential (BMP) production from fresh maize hybrids. Using these indicators from fresh maize, information on the differences between hybrids can be effectively obtained, albeit with some of the shortcomings of this proposed method. Samples of fresh maize plants (n = 384) from four hybrids were evaluated at two locations over four consecutive years (from 2018 to 2021). The dry matter content, averaged across all hybrids, all years and both locations, was 371 ± 42.3 g.kg−1. The colder and wetter the year, the significantly higher the starch content, lower the amylase-treated neutral detergent fibre content (aNDF) and lower the crude protein (CP), which was reflected in lower BMP. Weather did not significantly affect the net energy of lactation (NEL) or MPP values. The location significantly affected all monitored indicators, except BMP. The earlier the hybrid was at harvest time, the lower the NEL and MPP but the higher BMP contents were. This study is preliminary and must be repeated with more hybrids and under more different conditions.

Anaerobic co-digestion of Opuntia ficus-indica (L.) Mill. cladode with cow manure: Effect of different cultivars on biochemical methane potential

Nopal (Opuntia ficus-indica (L.) Mill.) cladode has garnered great interest recently in the area of agro-energy as emerging biomass due to its sustainable production. The objective of this study was to compare the biochemical methane potential of different nopal cultivars in co-digestion with cow manure. For this purpose, two different nopal cladodes: cow manure proportions (75:25 and 82:18) and three different cultivars (Atlixco, Copena V1, and Milpa Alta) were evaluated. The results indicated that the treatments with higher biochemical methane potential (mL CH4 g-1 VSfed) were Milpa Alta 75:25 (71.4), Copena V1 75:25 (66.5), Milpa Alta 82:18 (64.6), and Copena V1 82:18 (59.0), which showed no statistical difference (P>0.05) between them, whereas the Atlixco treatments (75:25 and 82:18) had the lowest (P<0.05) values (52.8 and 41.5, respectively). The results suggest that the cow manure proportion and nopal cultivar used in a co-digestion system may influence its biochemical methane potential.

Effect of Zeolite on the Methane Production from Chicken Manure Leachate

This study demonstrates the leachate characteristics derived from bench-scale leach-bed reactors (LBRs) filled with chicken manure (CM) and zeolite. Zeolite was used to maintain the necessary porosity for the leaching process and to adsorb ammonia. Fresh water was added for leachate production and removed daily, in order to estimate the readily leachable organic and nitrogen matter of the CM. Tests were conducted at two ratios of zeolite to bed (10% and 3.5% v/v CMbed). Other operating parameters studied were the amount of water added in the LBRs, the leachate recirculation rate, and the hydraulic retention time (HRT). A control LBR with river pebbles at a similar size and ratio (10% v/v) with zeolite was also studied. Some experiments were repeated with CM, which had different characteristics. Compared to the control test, the LBR with zeolite at 10% v/v yielded leachate with less NH3 and a higher biochemical methane potential (BMP). However, free ΝH3 in the control experiment was below the inhibition threshold, proving that zeolite contributes to the higher BMP of leachate, and that this effect is not only due to NH3 adsorption.

Enhancement of Biogas Production via Co-Digestion of Wastewater Treatment Sewage Sludge and Brewery Spent Grain: Physicochemical Characterization and Microbial Community

The present study intends to evaluate a synergy towards enhanced biogas production by co-digesting municipal sewage sludge (SS) with brewery spent grain (BSG). To execute this, physicochemical and metagenomics analysis was conducted on the sewage sludge substrate. The automatic methane potential test system II (AMPTS II) biochemical methane potential (BMP) batch setup was operated at 35 ± 5 °C, pH range of 6.5–7.5 for 30 days’ digestion time on AMPTS II and 150 days on semi-continuous setup, where the organic loading rate (OLR) was guided by pH and the volatile fatty acids to total alkalinity (VFA/TA) ratio. Metagenomics analysis revealed that Proteobacteria was the most abundant phyla, consisting of hydrolytic and fermentative bacteria. The archaea community of hydrogenotrophic methanogen genus was enriched by methanogens. The highest BMP was obtained with co-digestion of SS and BSG, and 9.65 g/kg of VS. This not only increased biogas production by 104% but also accelerated the biodegradation of organic matters. However, a significant reduction in the biogas yield, from 10.23 NL/day to 2.02 NL/day, was observed in a semi-continuous process. As such, it can be concluded that different species in different types of sludge can synergistically enhance the production of biogas. However, the operating conditions should be optimized and monitored at all times. The anaerobic co-digestion of SS and BSG might be considered as a cost-effective solution that could contribute to the energy self-efficiency of wastewater treatment works (WWTWs) and sustainable waste management. It is recommended to upscale co-digestion of the feed for the pilot biogas plant. This will also go a long way in curtailing and minimizing the impacts of sludge disposal in the environment.

Exploring the Biomethane Potential of Different Industrial Hemp (Cannabis sativa L.) Biomass Residues

Industrial hemp stands out as a promising candidate for clean and sustainable biomass-to-bioenergy systems due to its multipurpose, high biomass yield and resource efficiency features. In this study, different hemp biomass residues (HBRs) were evaluated as a potential feedstock for renewable biomethane production through anaerobic digestion (AD). The biochemical methane potential (BMP) of the raw and pretreated fibers, stalks, hurds, leaves and inflorescences was investigated by means of batch anaerobic tests. The highest BMP was obtained with the raw fibers (i.e., 422 ± 20 mL CH4·g VS−1), while hemp hurds (unretted), making up more than half of the whole hemp plant dry weight, showed a lower BMP value of 239 ± 10 mL CH4·g VS−1. The alkali pretreatment of unretted hurds and mechanical grinding of retted hurds effectively enhanced the BMP of both substrates by 15.9%. The mix of leaves and inflorescences and inflorescences alone showed low BMP values (i.e., 118 ± 8 and 26 ± 5 mL CH4·g VS−1, respectively) and a prolonged inhibition of methanogenesis. The latter could be overcome through NaOH pretreatment in the mix of leaves and inflorescences (+28.5% methane production).

Natural microalgal cultivation systems using primary effluent and excess sludge

ABSTRACT Microalgae have been recently cultivated using resources from wastewater treatment plants, including nutrients, CO2, and heat. In the present study, we focused on the natural cultivation of total microalgae rather than specific microalgae, for which culture conditions and the cultivation environment are difficult to prepare. Natural microalgal cultivation systems using 380-L raceway tanks were operated outdoors for 8 months and the effects of the culture substrate were investigated. The cultivation substrate was the primary effluent with or without excess sludge. The results showed that when diluted excess sludge was added to the substrate, microalgal biomass increased more than when the substrate contained only primary effluent. Additionally, the wastewater suspended matter and water quality were removed, reaching low levels. Microalgal culture systems using excess sludge showed higher organic acid content, higher biochemical methane potential, and higher efficiency in producing more microalgal biomass than wastewater treatment plant systems that did not use excess sludge.

Coupling acid pretreatment and dosing of Ni and Se enhances the biomethane potential of hazelnut skin

This study offers new insights and promising perspectives in view of the energy valorization of hazelnut skin (HS) as a potential feedstock for renewable biomethane production. The process originally comprised the coupling of chemical pretreatments and individual dosing of cobalt (Co), nickel (Ni) and selenium (Se) as enhancement strategies of the biochemical methane potential (BMP) of HS. The anaerobic digestion (AD) of the untreated HS resulted in a biomethane production of 299 ± 3 mL CH4·g VS−1. This was not positively nor negatively influenced by the addition of the three trace elements (TEs). Performing a 1% H2SO4 pretreatment on HS, a 104% increase of the biomethane yield (i.e. 612 ± 20 mL CH4·g VS−1) was obtained. Under the same pretreatment conditions, a peak of 66.2 mg HAc g VS−1 of total volatile fatty acids (VFAs) was achieved. The BMP of the H2SO4-pretreated HS was further improved by 12 and 16% through the addition of 90 μg Ni·g TS−1 and 270 μg Se·g TS−1 of HS, respectively. The application of a 1.6% NaOH pretreatment on HS led to a 41% higher BMP (i.e. 423 ± 24 mL CH4·g VS−1) compared to that achieved with the untreated material. However, not statistically significant effects were observed when dosing the TEs. In conclusion, a positive synergy between chemical pretreatments and TE supplementation was only observed with the H2SO4- pretreated HS. This was due to the higher VFA production and the more effective VFA conversion to methane in the presence of Ni and Se.

Anaerobic digestion of agro-industrial wastes of Bangladesh: Influence of total solids content

Producing bioenergy from the anaerobic digestion (AD) of poultry droppings (PD), press mud (PM), sugarcane bagasse (SB) and sugar beet roots and tops (SRT) could be an effective source of fuel and energy for processing sugar from sugar beet and sugarcane and for reviving and making the sugar industries profitable in Bangladesh. The total solids (TS) content is crucial for an optimum performance of the AD process. In this study, batch assays were conducted to determine the optimal TS contents on the mesophilic AD of PD, PM, SB and SRT with TS contents of 5, 8, 11 and 15%, respectively. The highest biochemical methane potential (BMP) were found 254, 121, 205 and 23 NL kg−1VS for PD, PM, SB and SRT after digestion for 90 days at TS content of 11%, 15%, 11% and 8%, respectively. The results indicate that the initial TS influenced the AD performance significantly and modeling showed that the optimal initial TS content for AD of PD, PM and SB ranged between 12 and 13%.The only exception was SRT, where an initial TS content of 8% is recommended.

Evaluation of methane production and energy conversion from corn stalk using furfural wastewater pretreatment for whole slurry anaerobic co-digestion

In this study, corn stalk (CS) was pretreated with furfural wastewater (FWW) for whole slurry anaerobic digestion (AD), which increased the degradability of CS components, changed the parameters in pretreatment slurry and improved the biochemical methane potential (BMP). The ultimate goal was to optimize the time and temperature for FWW pretreatment and evaluate whether FWW pretreatment is feasible from BMP and energy conversion. The results of path analysis suggested that lignocellulosic degradability (LD) was the main factor affecting methane production with the comprehensive decision of 0.7006. The highest BMP (166.34 mL/g VS) was achieved by the pretreatment at 35 °C for 6 days, which was 70.36% higher than that of control check (CK) (97.64 mL/g VS) and the optimal pretreatment condition was predicted at 40.69 °C for 6.49 days by response surface methodology (RSM). The net residual value (NRV) for the pretreatment of 35 °C and 6 days was the highest (0.6201), which was the most appropriate condition for AD in real application.

Biomethane from fish waste as a source of renewable energy for artisanal fishing communities

The potential of biogas production from fish waste as source of renewable energy for fishermen communities was evaluated. Four different fish waste concentrations (1%, 1.5%, 2% and 2.5% total solids (TS)) were digested during 28 days at mesophilic conditions. Biochemical Methane Potential (BMP), volatile fatty acids (VFA) concentration and ammonia concentration were analysed during the experiment. Energy production and economic projections were performed to estimate the number of families that can benefit from the biogas production in Tumaco, Colombia. The 1% TS had the highest BMP (464.5 mL CH4/g VS) and the lowest VFA production (2515 mg/L); in contrast, the 2.5% TS had the highest VFA production (11302 mg/L) and the lowest methane production (206.86 mL CH4/g VS). The treatments with 1.5%, 2% and 2.5% TS exhibited diauxic growth as result of different solubilisation rates in the fish waste components. The energetic and economic analyses estimated a yearly energy production of 489 MWh, which can satisfy the electric energy consumption or the cooking energy demand of 230 fishermen families. The results showed that biogas production from fish waste is a viable and sustainable alternative to adequately manage this material and provide renewable energy to fishermen communities.

Use of local resources as co-substrates in a farm-scale biogas plant

AbstractBiogas production is an established technology that is suitable for small-scale decentralized solutions, for example, on dairy cattle farms where manure is formed all year round. Cattle slurry can be co-digested with other organic biomasses to boost the production of renewable energy. The aim of this study was to outline the suitability of locally available co-substrates that are characteristic to the northern rural area in Lapland, Finland. Twelve different co-substrates originating from agriculture, reindeer meat production, fisheries and food processing were studied for their chemical characteristics and biochemical methane potential (BMP) in laboratory tests. As a result, all the tested co-substrates had a higher BMP than the cattle slurry, which could be a useful boost for farm-scale energy production. The BMP was the highest for used vegetable oil (851 l/kg VS) followed by the rainbow trout by-products (728 l/kg VS). BMP was the lowest for spoiled grass silage (265 l/kg VS) and the rumen contents of reindeer (289 l/kg VS). All substrates had high concentrations of the main nutrients, and small fish especially were rich in phosphorus (7.4 g/kg) and nitrogen (24.2 g/kg). Nutrient rich co-substrates increase the fertilizer value of digestate and the nutrient self-sufficiency of the farm.

Methane Production in Batch Anaerobic Digestion of Livestock Manures with Different Substrate Concentrations

This research aimed to evaluate the biochemical methane potential (BMP) of three livestock manures including swine manure (SM), chicken manure (CM), and dairy manure (DM) under the same conditions in batch anaerobic digestion (AD) including inoculum to substrate ratio, temperature, digestion time, concentration of total solids in the system, and reactor size. The experiments were performed on individual manure, 2-manure mixture, and 3-manure mixture. For the individual manure experiments, BMP of SM, CM, and DM were 326.97, 306.60, and 105.30 mL/gVSadded; and volatile solids (VS) removal values were 66.31, 62.47, and 52.02%, respectively. In the 2-manure mixture; SM: DM, SM: CM, and CM: DM ratios of 90:10%TS, the BMP were 278.15, 264.47, and 252.80 mL/gVSadded, respectively. In the 3-manure mixture, the maximum BMP was 200.82 mL/gVSadded under the SM: CM: DM combination of 74:20:6%TS. The conditions of the 3 experiments were similar: the total solids concentration at 20% of working volume and the temperature of 37°C. It could be concluded that each manure i.e., SM, CM, and DM could be used as raw material for methane production by anaerobic digestion. SM generated the highest BMP, followed by CM and DM, respectively. However, DM should not be used as raw material alone, except combining it with SM or CM for better methane production.

Performance of anaerobic treatment of blackwater collected from different toilet flushing systems: Can we achieve both energy recovery and water conservation?

Source-diverted blackwater (toilet wastewater) contains most of the organic energy in domestic wastewater and can be treated anaerobically to maximize energy recovery. Blackwater collected from toilets of different water saving options (e.g., conventional, dual and vacuum toilets) represents different characteristics, but their digestibility has not been discussed. In the present study, blackwater collected from different toilet flushing systems were characterized and compared in terms of chemical composition, digestibility and microbial population development during biochemical methane potential (BMP) tests. Interestingly, the highest BMP (48%) was achieved for conventional/dual flush toilet (5-9 L water/flush) blackwaters, whereas vacuum toilet (0.5-1.2 L water/flush) blackwater BMP was only 34%. Elevated free ammonia (FA) concentration (>205 mg L-1) appeared to contribute to the reduced digestibility of high-water saving toilet (< 1.5 L water/flush) blackwaters. Methanogenesis was the major FA inhibition step in anaerobic digestion as evident by batch kinetics studies; where Methanosarcina methanogens predominate in all blackwater, but ammonia-tolerance methanogens Methanoculleus and Methanomicrobiales were also predominant in blackwater collected from vacuum toilets. This work underlines that overall measures of sustainability also need to consider blackwater characteristics when designing resource recovery based source-diverted sanitary treatment systems.

Anaerobic Digestion of Three Microalgae Biomasses and Assessment of Digestates as Biofertilizer for Plant Growth

This study focused on the determination of biochemical methane potential of three different microalgae, Chlorella sp., Neochloris conjuncta, and Botryococcus braunii, and evaluation of the digestates as biofertilizers for corn growth. Biomethane Potential Test Unit consisting of twelve 2‐L flasks placed in temperature controlled water at 37°C was utilized. As Botryococcus braunii had the highest lipid content (9.54%), it also had the highest biochemical methane potential (290.63 N mL g−1 volatile solid). The digestates containing microalgae and inoculum were applied to corn plant with four application dosages (0 [control], 5, 10, and 15 t ha−1) based on dry mass. Results emphasized that the lowest dosage (5 t ha−1) of the digestates containing Chlorella sp. and inoculum (digested dairy manure with silage maize) increased plant dry weights by 9% and 23%, respectively. However, further increase in the dosages of the digestates containing Botryococcus braunii and Neochloris conjuncta resulted in a decrease of plant growth and nutrients uptake by corn plants from the soil. Results highlighted that increment of the dosages of the digestates containing Botryococcus braunii and Neochloris conjuncta led to a decrease of plant growth and nutrient uptake from soil. © 2018 American Institute of Chemical Engineers Environ Prog, 38:e13024, 2019