Digestion Treatment Research Articles

Protective Effects of Laminaria japonica Polysaccharide Composite Microcapsules on the Survival of Lactobacillus plantarum during Simulated Gastrointestinal Digestion and Heat Treatment.

To improve probiotics' survivability during gastrointestinal digestion and heat treatment, Lactobacillus plantarum was microencapsulated by spray-drying using Laminaria japonica polysaccharide/sodium caseinate/gelatin (LJP/SC/GE) composites. Thermogravimetry and differential scanning calorimetry results revealed that the denaturation of LJP/SC/GE microcapsules requires higher thermal energy than that of SC/GE microcapsules, and the addition of LJP may improve thermal stability. Zeta potential measurements indicated that, at low pH of the gastric fluid, the negatively charged LJP attracted the positively charged SC/GE, helping to maintain an intact microstructure without disintegration. The encapsulation efficiency of L. plantarum-loaded LJP/SC/GE microcapsules reached about 93.4%, and the survival rate was 46.9% in simulated gastric fluid (SGF) for 2 h and 96.0% in simulated intestinal fluid (SIF) for 2 h. In vitro release experiments showed that the LJP/SC/GE microcapsules could protect the viability of L. plantarum in SGF and release probiotics slowly in SIF. The cell survival of LJP/SC/GE microcapsules was significantly improved during the heat treatment compared to SC/GE microcapsules and free cells. LJP/SC/GE microcapsules can increase the survival of L. plantarum by maintaining the lactate dehydrogenase and Na+-K+-ATPase activity. Overall, this study demonstrates the great potential of LJP/SC/GE microcapsules to protect and deliver probiotics in food and pharmaceutical systems.

Moderate thermal post-treatment of digestate to improve biomethane production from agricultural- and food waste

The aim of this study was to assess the feasibility of moderate thermal treatment (70 °C for one hour) of digestate in combination with post-digestion targeting residual biomethane potentials from three full-scale biogas plants digesting food waste (FW), agricultural waste (AW) and a mixture of AW and manure (AWM). Dissolved organic carbon (DOC), biomethane production, and digestate quality were investigated. For the study six laboratory-scale continuously stirred tank biogas reactors working as post-digesters, with thermally-treated and non-treated digestate were used. DOC for thermally-treated digestates increased significantly (t-test, p < 0.05); FW-digestate (110–200 %), AW-digestate (24–92 %) and for AWM-digestate (4–73 %). Indexes for corresponding DOC quality showed lower apparent organic molecular weights and decreased aromaticity (with the exception of FW-digestate). Thermal treatment of digestate improved the biomethane production during post-digestion by 21–22 % (FW-digestate) and 9 % (AW-digestate). For AMW-digestate no clear positive effect was observed, most likely due to biogas plant operational process disturbances.

Enhanced anaerobic digestion of waste-activated sludge by thermal-alkali pretreatment: a pilot-scale study.

The composition of waste-activated sludge (WAS) is complex, containing a large amount of harmful substances, which pose a threat to the environment and human health. The reduction and resource utilization of sludge has become a development demand in sludge treatment and disposal. Based on the technical bottlenecks in the practical application of direct anaerobic digestion technology, this study adopted two different thermal and thermal-alkali hydrolysis technologies to pretreat sludge. A pilot-scale experiment was conducted to investigate the experimental conditions, parameters, and effects of two hydrolysis technologies. This study showed that the optimal hydrolysis temperature was 70 °C, the hydrolysis effect and pH can reach equilibrium with the hydrolysis retention time was 4-8 h, and the optimal alkali concentration range was 0.0125-0.015 kg NaOH/kg dry-sludge. Thermal-alkali combination treatment greatly improved the performance of methane production, the addition of NaOH increased methane yield by 31.2% than that of 70 °C thermal hydrolysis. The average energy consumption is 75 kWh/m3 80% water-content sludge during the experiment. This study provides a better pretreatment strategy for exploring efficient anaerobic digestion treatment technologies suitable for southern characteristic sewage sludge.

Material flow analysis of an upgraded anaerobic digestion treatment plant with separated utilization of carbon and nitrogen of food waste

Anaerobic digestion of food waste can recover carbon in the form of biogas, while the high concentration of ammonia nitrogen in the digestion effluent becomes troublesome. Therefore, some new treatment plants use three-phase centrifugation to separate homogenized food waste into nitrogen-rich fine slag for insect cultivation and carbon-rich liquid for anaerobic digestion. To analyze the effects of the carbon–nitrogen separation, an upgraded plant’s material and elementary flows were investigated. The three-phase separation process redistributed carbon and nitrogen, and the biogas slurry was the primary output. The principal endpoint for C was the crude oil, capturing 57.1 ± 13.1 % of the total input; the find slag collected 48.3 ± 6.9 % of the total N input, and the biogas slag accepted 52.9 ± 4.4 % of the P input. The carbon–nitrogen separation strategy can improve digestion efficiency and increase treatment benefits significantly, marking a promising direction for future developments in food waste utilization.

The influence of digestive tract protein on cytotoxicity of polyvinyl chloride microplastics

Microplastics in food and drinking water can enter the human body through oral exposure, posing potential health risks to the human health. Most studies on the toxic effects of microplastics have focused on aquatic organisms, but the effects of the human digestive environment on the physicochemical properties of microplastics and their potential toxicity during gastrointestinal digestion are often limited. In this study, we first studied the influence of interactions between digestive tract protein (α-amylase, pepsin, and trypsin) and microplastics on the activity and conformation of digestive enzymes, and the physicochemical properties of polyvinyl chloride microplastics (PVC-MPs). Subsequently, a simulated digestion assay was performed to determine the biotransformation of PVC-MPs in the digestive tract and the intestinal toxicity of PVC-MPs. The in vitro experiments showed that the protein structure and activity of digestive enzymes were changed after adsorption by microplastics. After digestion, the static contact angle of PVC-MPs was decreased, indicating that the hydrophilicity of the PVC-MPs increased, which will increase its mobility in organisms. Cell experiment showed that the altered physicochemical property of PVC-MPs after digestion process also affect its cytotoxicity, including cellular uptake, cell viability, cell membrane integrity, reactive oxygen species levels, and mitochondrial membrane potential. Transcriptome analyses further confirmed the enhanced biotoxic effect of PVC-MPs after digestion treatment. Therefore, the ecological risk of microplastics may be underestimated owing to the interactions of microplastics and digestive tract protein during biological ingestion.

Individual and group behavioral responses to nutritional state and context in a social fish

Understanding how animal collectives and societies form and function is a fundamental goal in animal biology. To date, research examining fish shoaling behavior has focused mostly on the general principles and ecological relevance of the phenomeon, while the ways in which physiological state (e.g., nutrition) affects collective behavior remain overlooked. Here, we investigated the shoaling behavior of common minnows (Phoxinus phoxinus) with three different nutritional states (control treatment: fasting for 24 h, fasting treatment: fasting for 7 days, and digestion treatment: 1 h after satiation feeding) across two ecological contexts (i.e., without and with food). No effects of either nutritional state or context were found on swimming speed, but the acceleration was greater in the digestion group than in the control group, with that in the fasting group being intermediate. Similar to change tendency in group length and group width of shoals, both interindividual distance and nearest neighbor distance were also greater in the fasting group than in the digestion group, suggesting that fasting and digestion may exert opposite driving forces on group cohesion. However, neither nutritional state nor context influenced the group area, group speed, group percent time moving, or group polarization. Both the foraging efficiency and the percentage of food items consumed by the fish shoals were greater in the fasting and control groups than in the digestion group. Our study suggested that one week of hunger and the energetically demanding stage of food digestion tend to have opposite influences on group shape, while the social foraging context does not influence the individual and group behavior of fish.

The fate of various organic compounds including pharmaceuticals in the treatment of landfill leachate and anaerobic digestate using deammonification

Studies focusing on the fate of organic compounds specifically recalcitrant organics and pharmaceuticals in a deammonification plant are scarce. This study downscaled a full-scale deammonification plant, which was being operated with the same wastewater streams of this study and evaluated for the first time the fate of different fractions of organic compounds in deammonification process along with the removal of nitrogenous compounds. Organic compounds in the feed and effluent were analyzed and their changes in the deammonification process were characterized. The results demonstrate that deammonification achieved over 90% of ammonium removal. COD monitoring revealed that around 11% of COD was reduced during the process mainly due to aerobic COD degradation and heterotrophic denitrifying bacteria. Analysis of the organic fractions revealed that high molecular weight components (around 11 kDa) are susceptible to removal and their concentrations tend to decrease in the reactor. Concentrations of humic substances, specifically fulvic acid-like substances, were reduced. Tracking nine different pharmaceutical residues revealed that morphine and cotinine were completely removed, while pregabalin and oxazepam which are known to be highly recalcitrant were more than 60% removed. The research finding can help in optimizing treatment processes by revealing the fate of different organic compounds, especially pharmaceuticals, within the deammonification process, thereby contributing to better effluent quality, regulatory compliance, and environmental protection.

Assessing nitrous oxide emissions from algal-bacterial photobioreactors devoted to biogas upgrading and digestate treatment

Nitrous oxide (N2O) emissions in High Rate Algal Ponds (HRAP) can negatively affect the sustainability of algal-bacterial processes. N2O emissions from a pilot HRAP devoted to biogas upgrading and digestate treatment were herein monitored for 73 days. The influence of the pH (7.5, 8.5, and 9.5), nitrogen sources (100 mg L−1 of N–NO2-, N–NO3-, and N–NH4+) and illumination on N2O emissions from the algal-bacterial biomass of the HRAP was also assessed in batch tests. Significantly higher N2O gas concentrations of 311.8 ± 101.1 ppmv were recorded in the dark compared to the illuminated period (236.9 ± 82.6 ppmv) in the HRAP. The batch tests revealed that the highest N2O emission rates (49.4 mmol g−1 TSS·h−1) occurred at pH 8.5 in the presence of 100 mg N–NO2-/L under dark conditions. This study revealed significant N2O emissions in HRAPs during darkness.

Cultivation of yeasts on liquid digestate to remove organic pollutants and nutrients and for potential application as co-culture with microalgae

In this study, the growth of yeast and yeast-like fungi in the liquid digestate from vegetable wastes was investigated in order to remove nutrients and organic pollutants, and for their application as co-culture members with green microalgae. The studied yeast strains were characterized for their assimilative and enzymatic profiles as well as temperature requirements. In the first experimental stage, the growth dynamics of each strain were determined, allowing to select the best yeasts for further studies. In the subsequent stage, the ability of selectants to remove organic pollutants was assessed. Different cultivation media containing respectively 1:3, 1:1, 3:1 vol ratio of liquid digestate and the basal minimal medium were used. Among all tested yeast strains, Rhodotorula mucilaginosa DSM 70825 showed the most promising results, demonstrating the highest potential for removing organic substrates and nutrients. Depending on the medium, this strain achieved 50–80% sCOD, 45–60% tVFAs, 21–45% TN, 33–52% PO43− reduction rates. Similar results were obtained for the strain Candida sp. OR687571. The high nutrient and organics removal efficiency by these yeasts could likely be linked to their ability to assimilate xylose (being the main source of carbon in the liquid digestate). In culture media containing liquid digestate, both yeast strains achieved good viability and proliferation potential. In the liquid digestate medium, R. mucilaginosa and Candida sp. showed vitality at the level of 51.5% and 45.0%, respectively. These strains seem to be a good starting material for developing effective digestate treatment strategies involving monocultures and/or consortia with other yeasts or green microalgae.

N fertilization strategies for the use of P-rich organic amendments in the restoration of soil productivity—short-term responses in two soils

To facilitate nutrient management and the use of manure as a feedstock for biogas production, manure is often separated into a solid and a liquid fraction. The former fraction is usually high in P and low in N, so when incorporated in the soil as fertilizer, it needs to be supplemented by N from, e.g., mineral fertilizers or nitrogen-fixing species. To explore strategies to manage N with solid-separated manure, we examined how the amount of digestate and the N:P ratio of pig digestate, i.e., manure that had partially undergone anaerobic digestion, affected the productivity of Westerwolds ryegrass and red clover in a pot experiment with one soil which was rich and another which was poor in plant nutrients. The soil and plant species treatments were combined with four doses of digestate, which gave plant available phosphorus (P) concentrations of 2, 4, 8, or 16 mg P100 g−1 soil. Ammonium nitrate was dosed to obtain factorial combinations of digestate amount and N:P ratios of 1.8, 4, 8, and 16. Clover was harvested once at the beginning of flowering (15 weeks after seeding), while Westerwolds ryegrass was allowed to regrow three times after being cut at the shooting stage (in total, 4 cuts, 6, 9, 12, and 15 weeks after seeding). Ryegrass yield increased by up to 2.9 times with digestate dosage. Interactions with the N:P ratio and soil type were weak. Hence, the effect of increasing the N:P ratio was additive across digestate dosages. Red clover biomass also increased by up to 39% with digestate dosage. Residual nutrients in the soil after red clover cultivation were affected by the initial differences in soil characteristics but not by digestate treatment or biomass of harvested red clover. A targeted N management is required to benefit from the P-rich digestate in grass cultivation, while the long-term effects of red clover culture on N input need further investigation.

The effects of microalgae use as a biofertilizer on soil and plant before and after its anaerobic (co-)digestion with food waste

The increase in food waste generation has resulted in significant challenges for its sustainable management. Anaerobic digestion coupled with microalgae-based ponds for digestate treatment can be used as a low-cost eco-friendly technology approach. In this case, microalgal biomass harvested from the ponds may be valorized into bioenergy (biogas) and soil conditioner and/or biofertilizers. The aim of the present study was to evaluate the microalgal biomass produced from a food waste digestate treatment ponds as agricultural fertilizer. For this purpose, microalgal biomass was tested before and after anaerobic digestion and co-digestion with food waste, exploring its potential for valorization. The inorganic fertilizer urea and soil with no fertilization were also used as treatments. The experimental design consisted of applying the treatments in pots cultivated with hybrid grass Brachiaria cv. Sabiá and distributed in randomized blocks in a controlled greenhouse. Microalgal biomass was mainly composed by Scenedesmus sp.. The assessed parameters showed comparable results on plant growth (i.e. number of tillers, fresh and dry matter and Chlorophyll content index) for fresh and digested microalgal biomass and inorganic fertilizer. Furthermore, it was observed that fresh microalgae provided the highest Phosphorus content in the leaf (21 %). Additionally, there were increases of 9 % in Nitrogen and 12 % in organic matter in the soil after applying digested microalgae compared to the control group without any fertilization. Finally, experimental data obtained suggests that microalgae-based biofertilizer holds the potential to replace inorganic fertilizer as a nutrient source. Moreover, it contributes to the valorization of by-products from organic waste treatment.

Waste-green infrastructure nexus: Green roof promotion by digestate and digestate biochar from food waste

Waste—Green Infrastructure Nexus is crucial to mitigate carbon emissions in waste disposal and promote eco-functions of green infrastructure in a circular bio-economy. Our purpose is to verify the feasibility of the nexus via “food waste anaerobic digestion — digestate/digestate biochar — green roof promotion”. The results found that food waste digestate and digestate biochar significantly promoted green roof plant growth, evapotranspiration, rainwater retention, runoff reduction, and prevention of nutrient leaching. Digestate treatments were better than digestate biochar for the green roof promotion. The promotion ranked consistently with 20 % digestate > 10 % digestate > 20 % digestate biochar > 10 % digestate biochar > control in stolon growth, leaf emergence, branching of Paspalum vaginatum, green roof establishment, rainwater retention, runoff reduction, and the leaching of nitrogen, phosphorus, potassium. This study demonstrated that food waste could be regenerated to promote urban green infrastructure to form a circular bio-economy by the Waste—Green Infrastructure Nexus.

Enhanced probiotic viability in innovative double-network emulsion gels: Synergistic effects of the whey protein concentrate-xanthan gum complex and κ-carrageenan

In this study, the whey protein concentrate and xanthan gum complex obtained by specific pH treatment, along with κ-carrageenan (KC), were used to encapsulate Lactobacillus acidophilus JYLA-191 in an emulsion gel system. The effects of crosslinking and KC concentration on the visual characteristics, stability, mechanical properties, and formation mechanism of emulsion gels were investigated. The results of optical imaging, particle size distribution, and rheology exhibited that with the addition of crosslinking agents, denser and more homogeneous emulsion gels were formed, along with a relative decrease in the droplet size and a gradual increase in viscosity. Especially when the concentration of citric acid (CA) was 0.09 wt%, KC was 0.8 wt%, and K+ was present in the system, the double-network emulsion gel was stable at high temperatures and in freezing environments, and the swelling ratio was the lowest (9.41%). Gastrointestinal tract digestive treatments and pasteurization revealed that the probiotics encapsulated in the double-network emulsion gel had a higher survival rate, which was attributed to the synergistic cross-linking of CA and K+ biopolymers to construct the emulsion gels. Overall, this study highlights the potential of emulsion gels to maintain probiotic vitality and provides valuable insights for developing inventive functional foods.

Effect of In Vitro Enzyme Digestion and Bile Treatment on Milk Extracellular Vesicles Stability.

Milk extracellular vesicles (EVs) are nanosized particles with potential immune bioactivities. This study examines their fate during in vitro infant gastrointestinal digestion (GI). Bovine milk is digested using the in vitro INFOGEST method, adjusted for the infant. To unravel the contribution of digestive enzymes from bile, milk is treated with digestive enzymes, bile, or a combination of both. EVs are collected posttreatment using differential ultracentrifugation. EVs characterization includes electrophoresis, immunoblotting, nanoparticle tracking analysis, and atomic force microscopy. EVs protein markers programmed cell death 6-interacting protein (ALIX), tumor susceptibility gene 101 (TSG101), cluster of differentiation 9 (CD9), and xanthine dehydrogenase (XDH) are detected after gastric digestion (G60), but their signal intensity is significantly reduced by intestinal conditions (p<0.05). Enzyme digestion, compared to bile treatment (I60+bile), results in a significant reduction of signal intensities for TSG101 and CD9 (p<0.05). Nanoparticle tracking analysis shows a significant reduction (p<0.05) of EV numbers at the end of the intestinal phase. EVs are detected by atomic force microscopy at the end of the intestinal phase, showing that intact EVs can survive upper gut digestion. Intact EVs can be found at the end of the intestinal phase. However, digestive enzymes and bile reduce the quantity and characteristics of EVs, with digestive enzymes playing a larger role.

A Study of Mathematical Models Used in Anaerobic Digestion of Organic Refuse

The mathematical computation and process evaluation of anaerobic digestion (AD) treatment of organic refuse (OR) has become quite common in process designing. Furthermore, the modelling of AD process is considered as well established and mature, and largely known as a mechanistic model structure. There are various mathematical models being used to comprehend the biochemical variations, rate of decomposition, and the methane or biogas production potentials. Moreover, these mathematical analyses of the models determine the computation of equilibrium points, helping to understand their internal stability with respect to feeding parameters, and compatibility to the output static characteristics of the entire AD process. Whereas numerical simulations are also carried out for specific biodegradation on web-based software. These simulations are useful to demonstrate the dynamic responses of the mathematical models to present the most mathematical viable solutions. However, the major issues lie in the application of AD in lab-based modelling needs improvement in characterization and the adaptation of new approaches to optimize bioenergy recoveries. Hence, this review paper discusses the selection and utilization of mathematical models for different conditions in AD treatment of OR for the best mathematical representations.

Forecasting the Mitigation Potential of Greenhouse Gas Emissions in Shenzhen through Municipal Solid Waste Treatment: A Combined Weight Forecasting Model

As a significant source of anthropogenic greenhouse gas emissions, the municipal solid waste sector’s greenhouse gas emission mode remains unknown, hampering effective decision-making on possible greenhouse gas emission reductions. Rapid urbanization and economic growth have resulted in massive volumes of municipal solid trash. As a result, identifying emission reduction routes for municipal solid waste treatment is critical. In this research, we investigate the potential of municipal solid waste treatment methods in lowering greenhouse gas (GHG) emissions in Shenzhen, a typical Chinese major city. The results showed that the combined treatment of 58% incineration, 2% landfill, and 40% anaerobic digestion (AD) had the lowest greenhouse gas emissions of about 5.91 million tons under all scenarios. The implementation of waste sorting and anaerobic digestion treatment of organic municipal solid waste after separate collection can reduce greenhouse gas emissions by simply increasing the incineration ratio.

Cultivation of Microalgae in Liquid Digestate to Remove Nutrients and Organic Contaminants

The goal of this research was to assess the efficiency of the liquid digestate treatment conducted with algal, environmental isolates illuminated entirely with sunlight. The photobioreactor was exposed to natural conditions and evaluated based on the reduction of chemical oxygen demand (COD), nitrogen compounds, and soluble phosphates. Microalgal and bacterial communities growing during the treatment process were studied. A high removal rate of soluble COD (= 91%) and nutrients (= 86%) was achieved. The average concentrations of nitrogen, phosphates, and COD in the reactor effluent were 95 mgN/L, 49 mg/L, and 735 mg O2/L, respectively. The overall algae-bacteria biomass productivity of 22 mg/L/d, calculated on the total suspended solids (TSS) basis, was recorded. The microbial analysis revealed the dominance of Tetradesmus obliquus followed by Microglena sp. in the first 14 weeks of the experiment. At the end of the experimental run, Chlorella sorokiniana cells appeared as a result of illumination intensity changes. The dominating bacteria belonged to Firmicutes (26.31%), Patescibacteria (17.38%), and Actinobacteriota (14.86%) and could have been responsible for the transformation of nitrogen and oxidation of organic contaminants. The research demonstrated that natural sunlight can successfully be used for efficient liquid digestate treatment with the algae-bacterial community.

Magnetic multilayer hydrogel oral microrobots for digestive tract treatment.

Oral administration is a convenient drug delivery method in our daily lives. However, it remains a challenge to achieve precise target delivery and ensure the efficacy of medications in extreme environments within the digestive system with complex environments. This paper proposes an oral multilayer magnetic hydrogel microrobot for targeted delivery and on-demand release driven by a gradient magnetic field. The inner hydrogel shells enclose designated drugs and magnetic microparticles. The outer hydrogel shells enclose the inner hydrogel shells, magnetic microparticles, and pH neutralizers. The drug release procedure is remotely implemented layer-by-layer. When the required gradient magnetic field is applied, the outer hydrogel shells are destroyed to release their inclusions. The enclosed pH neutralizers scour the surrounding environment to avoid damaging drugs by the pH environment. Subsequently, the inner hydrogel shells are destroyed to release the drugs. A set of experiments are conducted to demonstrate the wirelessly controllable target delivery and release in a Petri dish and biological tissues. The results demonstrated attractive advantages of the reported microrobot in microcargo delivery with almost no loss, remote controllable release, and drug protection by the pH neutralizers. It is a promising approach to advance next-generation precision oral therapies in the digestive system.

Fasting and digestion exert opposite effects on collective behavior in goldfish across contexts

AbstractAnimal groups are often composed of individuals with differences in their phenotypes (e.g. body size, personality, or internal nutritional state). Such differences in phenotypes between group mates can have significant consequences for the collective movement and behavior of a group. Here, we examined the effects of nutritional state and ecological context on the individual‐ and group‐level behaviors of groups of shoaling goldfish (Carassius auratus) across an open water environment, an environment with food, and an environment with food and refuge. Fish were randomly manipulated to be in one of three nutritional states (control: fasted for 24 h, fasting: fasted for 1 week, and digestion: 2 h after feeding) and comprised five group compositions: the all‐control (6 control fish), all‐fasting (6 fasted fish), all‐digestion (6 digesting fish), mixed con–fas (3 control fish and 3 fasted fish), and mixed con–dig treatment (3 control fish and 3 digesting fish). We found that compared to the control and fasted treatments, the fish in the digestion treatment had lower individual swimming speeds and nearest neighbor distances. However, group polarization was lower in the fasted treatment than in both the control and digestion treatments. For the two mixed treatments, individual and collective behaviors of the fish seemed to be intermediate in comparison to those of either the fasted or digestion treatments. Moreover, group‐level differences in collective behaviors were maintained across different contexts. All five treatments exhibited considerable context‐associated changes in collective behaviors, but behavioral repeatability was dependent on the nutritional state of the group composition. Our results suggest that nutritional state and ecological context influence both individual and collective behaviors and that fasting and digestion exert opposite effects on collective behaviors across ecological contexts.

Engineered algal systems for the treatment of anaerobic digestate: A meta-analysis

The objective of this review was to provide quantitative insights into algal growth and nutrient removal in anaerobic digestate. To synthesize the relevant literature, a meta-analysis was conducted using data from 58 articles to elucidate key factors that impact algal biomass productivity and nutrient removal from anaerobic digestate. On average, algal biomass productivity in anaerobic digestate was significantly lower than that in synthetic control media (p < 0.05) but large variation in productivity was observed. A mixed-effects multiple regression model across study revealed that biological or chemical pretreatment of digestate significantly increase productivity (p < 0.001). In contrast, the commonly used practice of digestate dilution was not a significant factor in the model. High initial total ammonia nitrogen suppressed algal growth (p = 0.036) whereas initial total phosphorus concentration, digestate sterilization, CO2 supplementation, and temperature were not statistically significant factors. Higher growth corresponded with significantly higher NH4–N and phosphorus removal with a linear relationship of 6.4 mg NH4–N and 0.73 mg P removed per 100 mg of algal biomass growth (p < 0.001). The literature suggests that suboptimal algal growth in anaerobic digestate could be due to factors such as turbidity, high free ammonia, and residual organic compounds. This analysis shows that non-dilution approaches, such as biological or chemical pretreatment, for alleviating algal inhibition are recommended for algal digestate treatment systems.