Cryptic Growth Research Articles

Significant in situ sludge yield reduction in an acidic activated sludge system

Minimizing sludge generation in activated sludge systems is critical to reducing the operational cost of wastewater treatment plants (WWTPs), particularly for small plants where bioenergy is not recovered. This study introduces a novel acidic activated sludge technology for in situ sludge yield reduction, leveraging acid-tolerant ammonia-oxidizing bacteria (Candidatus Nitrosoglobus). The observed sludge yield (Yobs) was calculated based on the cumulative sludge generation and COD removal during 400 d long-term operation. The acidic process achieved a low Yobs of 0.106 ± 0.004 gMLSS/gCOD at pH 4.6 to 4.8 and in situ free nitrous acid (FNA) of 1 to 3 mg/L, reducing sludge production by 58 % compared to the conventional neutral-pH system (Yobs of 0.250 ± 0.003 gMLSS/gCOD). The acidic system also maintained effective sludge settling and organic matter removal over long-term operation. Mechanism studies revealed that the acidic sludge displayed higher endogenous respiration, sludge hydrolysis rates, and higher soluble microbial products and loosely-bounded extracellular polymer substances, compared to the neutral sludge. It also selectively enriched several hydrolytic genera (e.g., Chryseobacterium, Acidovorax, and Ottowia). Those results indicate that the acidic pH and in situ FNA enhanced sludge disintegration, hydrolysis, and cryptic growth. Besides, a lower intracellular ATP content was observed for acidic sludge than neutral sludge, suggesting potential decoupling of catabolism and anabolism in the acidic sludge. These findings collectively demonstrate that the acidic activated sludge technology could significantly reduce sludge yield, contributing to more cost- and space-effective wastewater management.

Effects of sludge retention time on sludge reduction by ultrasound treatment: Sludge characteristics, microbial community, and metabolism

Both ultrasound and sludge retention time (SRT) enable the in-situ sludge reduction during wastewater treatment, but the influence of SRT on ultrasonic lysis – cryptic growth is unclear. This paper researched the influence of different SRTs on sludge lysis - cryptic growth using a sequential bio-reactor (SBR), then explained in details the changes of microorganisms in the SBR. The best SRT for sludge reduction was 30 d, and 47.29% reduction in sludge was achieved. The different SRTs changed the organic matter removal in the wastewater, and the removal rate decreased when SRT exceeded 60 d. The size of the sludge particles varied depending on the SRT, with the smallest size at SRT of 10d being 45.6 μm and the largest size at SRT of 90d being 110.0 μm. SEM showed that the sludge surface changed rough at longer SRT. FTIR and XPS showed notable effect in sludge functional group strength at SRT of 30 d. Extracellular polymeric substance (EPS) reduced the most at SRT of 30 d. The microbial communities of sludge varied with the SRT, and the unique main genus at SRT of 5, 15, 30 and 90 d were C10-SB1A, Lactococcus, Propioniciclava, Lactococcus, respectively. Furthermore, the SRT changed relative abundance of enzymes concerned with metabolism of carbon, nitrogen, and phosphorus. Similarly, SRT changed the metabolic rate, and the metabolic rate of carbon, nitrogen and phosphorus was best at SRT of 30 d.

Bud development, flower phenology and life history of holoparasitic Rafflesia cantleyi.

Despite being the world's largest single-flower, Rafflesia's biology and life history are still poorly understood due to its cryptic growth strategy on Tetrastigma vines. Previous studies have been mostly short-term, contrary to Rafflesia's long development period before blooming. Bud development and flower phenology of R. cantleyi was studied in a dipterocarp forest in Lata Jarum, Peninsular Malaysia. Seven populations, consisting of 247 buds, were monitored fortnightly for 65months in two discrete studies between 2009 and 2018. The bud size distribution of R. cantleyi is dynamic, progressively changing from small flower buds to larger buds before flowering. Buds < 5.0cm across had the slowest growth and highest mortality rates, while those > 15.0cm across demonstrated accelerated growth. The bud growth profiles of the same site clustered distinctively regardless of sex with successful blooming rate that varied greatly between sites, prompting speculation about their relatedness to the sites' physical attributes. We reported the first female-dominated population in Rafflesia's life history. Rafflesia cantleyi's blooming rate at Lata Jarum is moderate to high, with non-seasonal flowering phenology as evident by the lack of synchronisation and consistency between flowering and local rainfall patterns. Based on the field data of the present study and the published information of other Rafflesia species, R. cantleyi's life cycle was estimated between 4.0 and 5.3years. Our findings further explain Rafflesia's biology and life history and highlight the gap in knowledge of the natural habitats on the endoparasite's growth and fate potentially for future conservation and study.

Comprehensive assessment of the ultrasound lysis–cryptic growth technology for in situ sludge reduction: Mass balance and environmental and economic analyses

The ultrasonic lysis–cryptic growth technology can achieve in situ sludge reduction that relies on ultrasound to accelerate sludge lysis to provide organics for microorganism growth and utilization. However, it may be accompanied by high costs and unclear environmental and economic impacts. Therefore, this study evaluates the effect of the ultrasonic lysis–cryptic growth technology from the environmental and economic perspectives. For this purpose, a mass balance evaluation, life cycle assessment, comprehensive environmental assessment and economic assessment are conducted and three typical ultrasonic lysis frequencies (i.e. R1: 1/3d, R2: 1/d and R3: 2/d) are selected for verification. The mass balance evaluation results indicate that the ultrasonic lysis–cryptic growth technology increases CO2 release by 11% compared to conventional technology. The environmental and economic impacts of the ultrasound lysis frequency of 2/d are reduced by 26% and 49%, respectively. The comprehensive assessment shows that the optimal parameter is the ultrasound lysis frequency at 1/d because it can reduce carbon emission and reduce the total cost of 45.62%. In conclusion, the ultrasonic lysis–cryptic growth technology is better than the conventional technology with respect to the environmental and economic aspects. Therefore, the comprehensive assessment of ultrasound treatment sludge technology can lay the foundation for practical application.

The Performance and Mechanism of Sludge Reduction by the Bioaugmentation Approach

Simple SummaryActivated sludge-based wastewater treatment process is one of the most popular adopted systems in wastewater treatment plants around the world. Excess sludge is an inevitable byproduct of the process, and the enormous quantity has brought a significant burden on operational costs. Various physicochemical and biological methods have been developed. Biological-based methods are promising because of less chemical consumption and low operation cost comparing to physicochemical methods. Hence, the present study is aimed at searching for functional bacteria that could reduce sludge, enhance the performance of sludge reduction through optimization, and try to unveil the underlying mechanism during sludge reduction. A total of 19 strains that belong to Firmicutes, Proteobacteria, and Actinobacteria were successfully isolated and identified. Subsequently, the performance of sludge reduction by pure culture or mix-cultures was validated. In total, 21.2% and 13.9% of total suspended and volatile suspended solids were reduced within 48 h after optimization via response surface methodology. The three-dimensional excitation-emission matrix fluorescence spectrum and hydrolases test results revealed that the sludge reduction might be promoted by the strain mainly through hydrolysis via proteinase and amylase. The results obtained from the study could help us to find an effective and economical way to resolve the sludge issue.Millions of wastewater treatment plants (WWTPs) based on the activated sludge process have been established worldwide to help to purify wastewater. However, a vast amount of sludge is inevitably generated, and the cost of sludge disposal could reach over half of the total operation cost of a WWTP. Various sludge reduction techniques have been developed, including physicochemical, biological, and combinational methods. Micro-organisms that could reduce sludge by cryptic growth are vital to the biological approach. Currently, only limited functional bacteria have been isolated, and the lack of knowledge on the underlying mechanism hinders the technique development. Therefore, the present study is aimed at isolating sludge-reducing bacteria and optimizing the sludge reduction process through response surface methodology. Nineteen strains were obtained from sludge. The mix-cultures did not show a higher sludge reduction rate than the pure culture, which may be ascribed to the complicated interactions, such as competition and antagonistic effects. In total, 21.2% and 13.9% of total suspended and volatile suspended solids were reduced within 48 h after optimization. The three-dimensional excitation-emission matrix fluorescence spectrum and hydrolases test results revealed that the sludge reduction might be promoted by the strain mainly through hydrolysis via proteinase and amylase. The results obtained from the study demonstrate the potential of using micro-organisms for sludge reduction through cryptic growth.

Neglected plant parasites: Mitrastemonaceae

Mitrastemonaceae are a remarkable family of parasitic flowering plants. The two species that make up this family have a disjunct distribution and a peculiar appearance. Both are devoid of roots, stems, and regular leaves and live inside the roots of their host plants for most of their life cycle. Their white-pink flowers and berry-like fruits become visible on the forest floor only during their reproductive phase. This cryptic growth form, allied to their patchy distribution, and the muted color of their flowers have contributed to making Mitrastemonaceae one of the least collected and analyzed families of parasitic plants. On the other hand, recent findings regarding the phylogenetic position of the family have advanced our understanding of the family's biogeography and prompted a reexamination of their ecology and evolution. Here we review key aspects of the life cycle, reproductive ecology, and host relationships in the family Mitrastemonaceae to identify gaps in our current knowledge and instigate future research.

Huddling together to survive: Population density as a survival strategy of non-spore forming bacteria under nutrient starvation and desiccation at solid-air interfaces

Acclimation and flexible response mechanisms are survival adaptations allowing prokaryotic cells to colonize diverse habitats and maintain viability in nature. Lack of water significantly impacts cellular response, which can be partially compensated for through community interactions and accessing survival means beyond the cell’s boundaries. In the present study, higher numbers of cultivable Gram-positive Arthrobacter sp. and Gram-negative Pseudomonas stutzeri cells were found on surfaces when high population density was used after prolonged periods of desiccation and nutrient starvation. Total cell counts during desiccation periods decreased slower than culturable cell counts independently from initial population density. The presence of homogenate, prepared by filtering homogenized cultures through a 0.2 µm filter, extended culturability of Arthrobacter sp. cells, while intact heat-killed cells extended the culturability of Arthrobacter sp. and P. stutzeri. Our results suggest very slow cell membrane breakdown for desiccated bacterial cells at solid-air interfaces over extended time spans, which may serve as reservoirs of nutrients, and may potentially provide trace amounts of water for surviving cells. Higher initial population density and recycling of resources from “zombie”-like cells, may support growth in a similar fashion as access to cell lysates or the contents of heat-killed cells analogous to dead-phase cultures where some cells experience cryptic growth.

Influence of cell lysis by Fenton oxidation on cryptic growth in sequencing batch reactor (SBR): Implication of reducing sludge source discharge

The cell lysis-cryptic growth was implemented by Fenton oxidation in sequencing batch reactor. Optimizing sludge lysis condition could maximize the release of nutrients and sludge disintegration degree. After Fenton oxidation, the extracellular polymeric substance was obviously destroyed with the sludge average particle decreased from 64 μm to 36 μm. After 5% of the settled sludge in sequencing batch reactor (SBR) was oxidized by Fenton and then returned to SBR, the mixed liquor suspended solids (MLSS) decreased by 19.3% at the end of 35 days operation, the average mixed liquor volatile suspended solids/mixed liquor suspended solids (MLVSS/MLSS) was promoted by 13.3% during the entire operation. Returning lysed sludge had no significant influence on the organics and nitrogen removal, but the total phosphorus removal was distinctly enhanced by generating FePO4 precipitate. Additionally, returning lysed sludge suppressed nitrifying bacteria and promoted denitrifying bacteria slightly. Consequently, the cell lysis-cryptic growth for reducing sludge source discharge from wastewater biological treatment could be achieved on the premise of ensuring effluent quality.

Cryptic growth strategies of the Cambrian coralCambroctoconus: flexible modes of budding and growth in immediate response to available space

AbstractThe Cambrian coralCambroctoconusoccurs selectively in the crypts of calcimicrobeEpiphytonreefs of the Zhangxia Formation (Miaolingian) in Shandong Province, North China. These cryptobionts preferentially grow laterally and/or downward, in some cases showing pendent growth from the ceilings of the reef framework. The upside‐down growth is clearly shown by the downward‐oriented aperture and the presence of fork‐like holdfasts at its base. The coral aggregations reveal two cryptic growth strategies: one involves the prevalence of far smaller individuals in vertically narrow spaces; the other involves the predominance of modular individuals in large cavernous spaces. Offset individuals frequently appear projecting downward and are connected to each other in a chain‐like fashion. Individuals often undergo rejuvenescence laterally and downward, when the growth directions may change. Therefore, the size and modularity of individuals and the direction of budding depend largely upon the cryptic microenvironments available at the time. The cryptobionts make the best use of vacant spaces by modifying the location of budding and altering their growth directions through rejuvenescence. The cryptic growth strategies found inCambroctoconusindicate a certain degree of morphological variability in the modules. More importantly, they indicate that the individuals flexibly and exquisitely utilized the microbial crypts that were still predominant even during the middle Cambrian. These modes of cryptic growth demonstrate the age‐specific exploitation of niches by sessile skeletal organisms that was facilitated by the development of a firm attachment structure.

Temperature as competitive strategy determining factor in pulse-fed aerobic bioreactors.

Exposing a microbial community to alternating absence and presence of carbon substrate in aerobic conditions is an effective strategy for enrichment of storage polymers (polyhydroxybutyrate, PHB) producing microorganisms. In this work we investigate to which extent intermediate storage polymer production is a temperature independent microbial competition determining factor. Eight parallel bioreactors were operated in the temperature range of 20-40 °C, but intermediate storage polymer production was only obtained at 25-35 °C. Besides PHB production and consumption, cell decay and subsequent cryptic growth on lysis products was found to determine process properties and the microbial community structure at all operational temperatures. At 40 °C decay processes cannot be overcome with additional energy from storage polymers, and fast-growing microorganisms dominate the system. At 20 °C, highly competitive communities with ambiguous storage properties were enriched. The results described here demonstrate that a rigorous experimental approach could aid in the understanding of competitive strategies in microbial communities.

Assessment of the Sludge Reduction of the Metabolic Uncoupler 3,3',4',5-tetrachlorosalicylanilide (TCS) in Activated Sludge Culture.

Batch experiments were completed to assess the sludge reduction of the metabolic uncoupler 3,3′,4′,5-tetrachlorosalicylanilide (TCS). The effects of various TCS concentrations on sludge yield were evaluated and the mechanisms associated with sludge reduction were assessed. We discovered that TCS addition resulted in a reduction in sludge. Furthermore, a low dose of TCS (≤3 mg/L) resulted in a slight reduction in the efficiency of the wastewater treatment system, while >3 mg/L TCS reduced matrix removal efficiency, with an especially remarkable inhibition effect on ammonia removal. An increase in TCS addition was associated with a gradual decrease in both the electron transport system (ETS) activity and the specific cellular ATP (SATP) in the TCS system. It was demonstrated that TCS plays an important role in metabolic uncoupling. However, with the addition of TCS, both contents and compositions were increased, and the protein content increased more than polysaccharide production in extracellular polymeric substances (EPS). At TCS concentrations of ≤3 mg/L, DNA content was stable, but it increased rapidly from 4.97 mg/L to 15.34 mg/L as the TCS concentration was elevated from 6 mg/L to 12 mg/L. This implied that the mechanisms of sludge reduction were different for different TCS concentrations, including uncoupling metabolism, maintenance metabolism and lysis–cryptic growth.

Status and Research Progress on Sludge Reduction Technologies

With wastewater treatment capacity increasing rapidly, the issue of excess sludge treatment becomes serious for wastewater treatment plant. Sludge reduction technology becomes one of the effective ways to resolve excess sludge issue at present. Application status of wastewater treatment with sludge reduction were elaborated from uncoupling, cryptic growth and predation of micro faunal three aspects. The principles and characteristics of these techniques were introduced, and their research.

Effects of polystyrene nanoparticles on the microbiota and functional diversity of enzymes in soil

BackgroundThe increasing production of nanoplastics and the fragmentation of microplastics into smaller particles suggest a plausible yet unclear hazard in the natural environment, such as soil. We investigated the short-term effects (28 days) of polystyrene nanoparticles (PS-NPs) on the activity and biomass of soil microbiota, and the functional diversity of soil enzymes at environmental relevant low levels in an incubation experiment.ResultsOur results showed a significant decrease in microbial biomass in treatments of 100 and 1000 ng PS-NP g−1 DM throughout the incubation period. Dehydrogenase activity and activities of enzymes involved in N-(leucine-aminopeptidase), P-(alkaline-phosphatase), and C-(β-glucosidase and cellobiohydrolase) cycles in the soil were significantly reduced at day 28 suggesting a broad and detrimental impact of PS-NPs on soil microbiota and enzymes. Leucine-aminopeptidase and alkaline-phosphatase activities tended to decrease consistently, while β-glucosidase and cellobiohydrolase activities increased at high concentrations (e.g., PS-NP-1000) in the beginning of the incubation period, e.g., at day 1. On the other hand, basal respiration and metabolic quotient increased with increasing PS-NP application rate throughout the incubation period possibly due to increased cell death that caused substrate-induced respiration (cryptic growth).ConclusionsWe herewith demonstrated for the first time the potential antimicrobial activity of PS-NPs in soil, and this may serve as an important resource in environmental risk assessment of PS-NPs in the soil environment.

Cell Lysis Cryptic Growth Method Using Ozonation for Excess Sludge Minimization: A Review

Cell Lysis Cryptic Growth Method Using Ozonation for Excess Sludge Minimization: A Review

Investigation of the accumulation of ash, heavy metals, and polycyclic aromatic hydrocarbons to assess the stability of lysis-cryptic growth sludge reduction in sequencing batch reactor.

The accumulation of ash, heavy metals, and polycyclic aromatic hydrocarbons (collectively called potential accumulating substances, PAS) was evaluated to ascertain the stability of lysis-cryptic growth sludge reduction process (LSRP) for municipal sludge treatment. One sequencing batch reactor (SBR) incorporated with homogenization was run to test the LSRP and another SBR as a control. The continuous monitoring results for 2months showed that the ash and heavy metals slightly increased, and the polycyclic aromatic hydrocarbons decreased by 18.0%, indicating that there may be negligible accumulations during the LSRP. Their accumulations met pattern I, as demonstrated by statistical analysis, proving no PAS accumulation for LSRP. This was further confirmed by sludge activity and system performance. Moreover, the mechanism for no PAS accumulation was discussed. It was concluded that the LSRP was stable with no worries about PAS accumulation under the operational conditions.

Reduction of excess sludge in a sequencing batch reactor by lysis-cryptic growth using quick lime for disintegration under low temperature

ABSTRACTIn the present study, quick-lime-based thermal-alkaline sludge disintegration (SD) under low temperature was combined with cryptic growth to investigate the excess sludge reduction efficiency in the sequencing batch reactor (SBR). The optimized condition of SD was as follows: T = 80℃, pH = 11, t = 180 min, and the SD rate was about 42.1%. With 65.6% of excess sludge disintegrated and returned to the SBR, the system achieved sludge reduction rate of about 40.1%. The lysis-cryptic growth still obtained satisfactory sludge reduction efficiency despite the comparative low SD rate, which suggested that disintegration rate might not be the decisive factor for cryptic-growth-based sludge reduction. Lysis-cryptic growth did not impact the effluent quality, yet the phosphorus removal performance was enhanced, with effluent total phosphorus concentration decreased by 0.3 mg/L (33%). Crystal compounds of calcium phosphate precipitate were detected in the system by Fourier transform infrared spectroscopy and X-ray diffraction, which indicated the phosphorus removal potential of SD using lime. Moreover, endogenous dehydrogenase activity of activated sludge in the lysis-cryptic system was enhanced, which was beneficial for sludge reduction. SD and cryptic growth in the present study demonstrates an economical and effective approach for sludge reduction.

Evaluation of sludge reduction of three metabolic uncouplers in laboratory-scale anaerobic–anoxic–oxic process

To evaluate the sludge reduction of three metabolic uncouplers (3,3′,4′,5-tetrachlorosalicylanilide (TCS), 2,4-dichlorophenol (DCP), and tetrakis (hydroxymethyl) phosphonium sulfate (THPS)), we conducted continuous experiments on laboratory-scale anaerobic–anoxic–oxic processes. The three metabolic uncouplers were separately added in each oxic tank of the three systems, and a system without uncoupler addition was used as control. During the 85-day operation, sludge production and observed growth yields decreased to 38.6% and 16.98%, 43.4% and 17.55%, and 39.3% and 17.04% by the addition of TCS, DCP, and THPS, respectively. The addition of metabolic uncouplers slightly reduced the wastewater treatment efficiencies of the system (about 1.1–8.7%) and increased sludge SVIs (about 69.9–80.6%). Meanwhile, the differences among three metabolic uncouplers were little. Besides metabolic uncoupling and maintenance metabolism, which exist in the TCS- and DCP-added systems, lysis–cryptic growth also exists in the THPS-added system.

Kinetic analysis of biological degradation for tetramethylammonium hydroxide (TMAH) in the anaerobic activated sludge system at ambient temperature

With rapid development of thin-film transistor liquid crystal display industries, improvements of the wastewater treatments for spent developing fluid (Tetramethylammonium hydroxide (TMAH)) is essential. As an alternative to the conventional aerobic processes, an anaerobic process in ambient temperature composed of a suspended sludge reactor and subsequent two gravity thickeners with addition of flocculants was elaborated. Methylotrophic TMAH-degraders were enriched from an anaerobic digester at a municipal wastewater treatment plant, feeding TMAH as a sole substrate. In the system TMAH was converted to methane via methanol whilst trimethylamine, dimethylamine, monomethylamine and ammonium were sequentially produced with the biomass yield of 0.14 gCOD/gTMAH, maximum specific growth rate at 0.372d⿿1 and specific decay rate at 0.017d⿿1 under 23°C. The system could remove TMAH at 0.37⿿1.2kgTMAH/m3/d with 2000⿿6000mg/L of sludge concentration in the reactor, and achieved low effluent dissolved organics at about 2⿿5mgC/L. A kinetic model of TMAH degradation, including cryptic growth of ordinary acidogens, acetotrophic and hydrogenotrophic methanogens from the decayed TMAH-degraders was built, and validated using a quantitative PCR method. Since the calculated fractions of bacterial and archaeal biomass were consistent with those detected, the kinetic model based on the metabolic pathways could be used as a design platform to maximise the target species and reaction rates in the new system.

Study of the diversity of microbial communities in a sequencing batch reactor oxic-settling-anaerobic process and its modified process.

To further reveal the mechanism of sludge reduction in the oxic-settling-anaerobic (OSA) process, the polymerase chain reaction - denaturing gradient gel electrophoresis protocol was used to study the possible difference in the microbial communities between a sequencing batch reactor (SBR)-OSA process and its modified process, by analyzing the change in the diversity of the microbial communities in each reactor of both systems. The results indicated that the structure of the microbial communities in aerobic reactors of the 2 processes was very different, but the predominant microbial populations in anaerobic reactors were similar. The predominant microbial population in the aerobic reactor of the SBR-OSA belonged to Burkholderia cepacia, class Betaproteobacteria, while those of the modified process belonged to the classes Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria. These 3 types of microbes had a cryptic growth characteristic, which was the main cause of a greater sludge reduction efficiency achieved by the modified process.

Sample Preparation for Fungal Community Analysis by High-Throughput Sequencing of Barcode Amplicons.

Fungal species participate in vast numbers of processes in the landscape around us. However, their often cryptic growth, inside various substrates and in highly diverse species assemblages, has been a major obstacle to thorough analysis of fungal communities, hampering exhaustive description of the fungal kingdom. Recent technological developments allowing rapid, high-throughput sequencing of mixed communities from many samples at once are currently having a tremendous impact in fungal community ecology. Universal DNA extraction followed by amplification and sequencing of fungal species-level barcodes such as the nuclear internal transcribed spacer (ITS) region now enable identification and relative quantification of fungal community members across well-replicated experimental settings. Here, we present the sample preparation procedure presently used in our laboratory for fungal community analysis by high-throughput sequencing of amplified ITS2 markers. We focus on the procedure optimized for studies of total fungal communities in humus-rich soils, wood, and litter. However, this procedure can be applied to other sample types and markers. We focus on the laboratory-based part of sample preparation, that is, the procedure from the point where samples enter the laboratory until amplicons are submitted for sequencing. Our procedure comprises four main parts: (1) universal DNA extraction, (2) optimization of PCR conditions, (3) production of tagged ITS amplicons, and (4) preparation of the multiplexed amplicon mix to be sequenced. The presented procedure is independent of the specific high-throughput sequencing technology used, which makes it highly versatile.