Pretreatments for Enhancing Sewage Sludge Reduction and Reuse in Lipid Production

doi:10.21203/rs.3.rs-54106/v1

Download PDF

Research

Pretreatments for Enhancing Sewage Sludge Reduction and Reuse in Lipid Production

https://doi.org/10.21203/rs.3.rs-54106/v1

This work is licensed under a CC BY 4.0 License

Journal Publication

published 14 Dec, 2020

Read the published version in Biotechnology for Biofuels and Bioproducts →

You are reading this older preprint version

Read the latest preprint version →

Background: Converting wastewater sludge for lipid is considered as one of the best strategies of sludge management. The current problem of lipid production from sludge is the low yield due to the low availability of easily uptaken materials in sludge. Pretreatments are efficient methods to improve sludge bioavailability.

Results: In this study, it was observed that the soluable chemical oxygen demand (SCOD) had significantly increased after different pretreatment.The SCOD in the supernatant was increased from 32.64±5.19 to 180±13 mg/L, 924±17 mg/L, 1030±6 mg/L and 3708±22 mg/L after acidic, alkaline, microwave irradiation and ultrasonication pretreatment, respectively. Pretreatments have also increased the release in total nitrogen (TN) and total phosphorus (TP) from solids. The sludge after different pretreatments were used as medium for lipid production, thighest lipid content (36.67% g/g) was obtained in the fermentation with ultrasonication pretreatment sludge, and the sludge reduction was 63.10%.

Conclusion: It was found that ultrasonication pretreatment was the most efficient way to increase the sludge biodegradability (SCOD), to release TN and TP from solid phase to liquid phase. Pretreated sludge for lipid production achieved significant improvement lipid yield and sludge reduction. Lipids produced from pretreated sludge was transesterified to biodiesel and the analysis showed that the biodiesel had similar composition as commercial biodiesel. The study reveals that pretreatment on sludge is a promising method for enhancing biological sludge management efficiency.

Biotechnology and Bioengineering

Sludge reduction

lipid production

pretreatment

ultrasonication

biodiesel

Along with the development of the society, wastewater discharge amount sharply increases due to the human activities (Grobelak et al., 2019). Aimming to reduce its environmental and health risks, wastewater was collected and treated in the wastewater treatment plants. Nevertheless, large amount of sewage sludge, which is an unavoidable by-product of wastewater treatment, is generated (Grobelak et al., 2019). For decades, sewage sludge was considered as a waste. Treatments, such as digestions (aerobic and anaerobic), landfill, and incineration, are mainly used for the reduction or dispose of the sewage sludge (Yang et al., 2015; Zhang et al., 2017). These sludge treatments generally require large land occupy, high energy input and high cost (Pilli et al., 2015; Qian et al., 2016).

In fact, it has been well realized that sewage sludge contains various useful materials such as carbon, nitrogen and phosphorus, which can be recovered by physical, chemical and/or biological methods (Zhang et al., 2017). Recovery of nitrogen and phosphorus as fertilizers is one of the best choice (Černe et al., 2019). In additioin, carbon recovery from sludge could be the main focus of sludge treatment as it is the most abundant component in sewage sludge (Chanaka Udayanga et al., 2019; Gherghel et al., 2019). Carbon recovery from sludge is generally accomplished through direct extraction or converting it to value-added products (Gherghel et al., 2019). Biogas, lipids, extracellular polymeric substances, bioplastics, short-chain fatty acids are common value-added products generated from sewage sludge (Paolini et al., 2018; Raheem et al., 2018; Zhu et al., 2017). It provides new option for sludge management and resource recyceling (Ahmad et al., 2016).

Lipids are good resources for biodiesel production (Zhu et al., 2017). It has been found both in the primary and secondary sludge; however, the lipid content in raw sludge (g lipids/g sludge) is quite low (Zhang et al., 2014b). Thus, direct lipid extraction from sludge has limited sludge reduction and is not attractive (Siddiquee & Rohani, 2011). Refermentation of sludge is a promising way to increase lipid content and enhance sludge reduction (Revellame et al., 2013). Additionally, it was found that biodiesel production from lipid accumulated by sludge fermentation had economic and energetic feasibility, and it was principally depending on the amount of sludge reduction and lipid accumulation (Chen et al., 2018; Zhang et al., 2013).

Raw sewage sludge is a mixture of complex organic compounds, which has very low biodegradability. Pretreatment is an efficient way of breaking down complex materials of sludge (Carrère et al., 2010; Zhang et al., 2014c). Physical, chemical and biological pretreatments were investigated to release nutrients from sewage sludge, and was observed to highly assistant the utilization of sludge by microorganisms (Carrère et al., 2010). So far, the impact of sludge pretreatment on methane and hydrogen production has been widely perofmed; however, few has evaluated its impact on lipid production. Due to the concern of high cost, difficult management and low stability, the full-scale application of biological pretreatments are scarce (Brémond et al., 2018). Thermal pretreatment is an effective sludge disintegration method despite its issue of energy efficiency (Kor-Bicakci & Eskicioglu, 2019). The emerging and promising mechanical sludge pretreatment is ultrasonication. Sludge pretreatment using ultrasonication has numerous advantages such as efficient sludge disintegration (> 95%), improvement in biodegradability and biosolids quality, no chemical addition, less retention time, sludge reduction and energy recovery (Pilli et al., 2011). Chemical sludge pretreatments, including acidic, alkaline, and oxidative prtreatments, have been applied to enhance the sludge biodegradation (Harris & McCabe, 2015). Alkali and acid reagents are effective to solubilize lignin and hemicellulose in the biomass (Rodriguez et al., 2015). Moreover, pretreatment could also provide sterilization function, which is highly favorable for lipid production from pure culture.

This study is aim to increase sludge reduction, carbon recovery from sewage sludge for lipid production. Acidic pretreatment, alkaline pretreatment, microwave irradiation and ultrasonication were investigated on the enhancement of nutrient and carbon release from sludge, the increase of lipid production and improvement of sludge reduction. Sludge reduction and reuse for lipid production after pretreatment were compared with other sludge regulation methods and its further application was discussed.

Pretreatment impact on SCOD and nutrients release from sludge

SCOD was found to be a reliable character to represent the soluble organics in the liquid phase. The increase of SCOD indicated the release of organic matters from solid into liquid (Zhang et al., 2009).

Sludge samples collected before and after pretreatment was centrifuged and the SCOD in the supernatant was measured. It can be seen that the SCOD in the supernatant before pretreatment was 32.64 ± 5.19 (Fig. 1). In this study, raw sludge was collected from secondary sedimentation, thus, the SCOD in the supernatant of the raw sludge should be the same as the effluent of secondary sedimentation. It was reported that SCOD in the effluent of secondary sedimentation was generally below 40 mg/L (Ekblad et al., 2019; Shin et al., 2019). Hence, the result is consistent with the reality.

In this study, it was observed that the SCOD had significantly increased after different pretreatment.The SCOD in the supernatant was increased from 32.64 ± 5.19 to 180 ± 13 mg/L, 924 ± 17 mg/L, 1030 ± 6 mg/L and 3708 ± 22 mg/L after acidic, alkaline, microwave irradiation and ultrasonication pretreatment, respectively (Fig. 1), which was 6.5 times, 23.3 times, 23.5 times and 167.5 times higher than that in the original sludge, respectively. It suggests that the pretreatments effectively assistant the release of organic matters from solid.

Among all, ultrasonication pretreatment provides the highest SCOD increase which was 3.6, 4 and 21 times higher than the microwave, alkaline and acidic pretreatment, respectively (Fig. 1). Therefore, ultrasonication was considered to be the most efficient way for soluable substances release from sludge. During ultrasonication, microbubbles and free radicals are generated which could efficiently destroy microbial cells, breakdown complex organic compounds and release nutrients to the supernatant (Pilli et al., 2011). It was reported that the release of organic matters and the increase of SCOD with the ultrasonic density and ultrasonic intensity followed the first-order reaction (Grönroos et al., 2005; Li et al., 2016; Mehrdadi and Kootenaei, 2018; Wang et al., 2005). It has been reported that a neglectable amount of organic matters was oxidized during the ultrasonication pretreatment, and soluable materials were mainly transferred from the solid phase to the liquid phase (Kidak et al., 2009). In this study, the MLSS of the sludge solution before and after ultrasonication was 7.14 g/L and 6.72 g/L, respectively. It indicates that the MLSS reduction of sludge due to ultrasonication was 5.88% (=(6.72–7.14)/7.14 × 100%).

It was noticed that the TN in the supernatant of raw sludge was very high (around 40.50 mg/L) which was expected to be below 15 mg/L according to the Criteria of Grade I of the "Standard for Discharge of Pollutants From Urban Sewage Treatment Facilities" (GB18918-2002). It indicates that the nitrogen concentration in the effluent of secondary sedimentation was high and an excessive amount of nitrogen would be discharged to the natural waters if addition treatment has not been applied after secondary treatment. In the last decades, excessive nitrogen discharging from the wastewater treatment plant has caused severe eutrophication and destructed the aquatic ecosystems (Yu et al., 2019). Different from other pretreatments, TN concentration in the supernatant was nearly not changed (from 40.5 mg/L to 45 mg/L) after acidic pretreatment (Fig. 1). Similar results have been reported by others as well (Wang, 2016; Wang et al., 2019). Acidic pretreatment could effectively cause the cell death due to dehydration; however, it is not efficient for breaking cell membrane. It suggests that no significant realse of intracellular protein occurs in acidic pretreatment.

TN in the supernatant was increased from 40.5 mg/L to 112 mg/L, 144 mg/L and 249 mg/L after alkaline, microwave irradiation and ultrasonication pretreatment, respectively (Fig. 1). Compared to acidic pretreatment, alkaline treatment has better performance on TN release. Alkali could react with phospholipid (the mian composition of cell membrane) to occur saponification, and thus disrupt the cell and release the intracellular products (such as protein). It hence increases the TN in the supernatant. It can be seen that microwave and ultrasonication pretreatment achieved efficient TN release and ultrasonication provides better performance (Fig. 1). As been discussed above, free radicals was generated during ultrasonication that could break and deconstruct the cells, and thus lead to release of protein and polysaccharide into the supernatant (Grönroos et al., 2005; Pilli et al., 2011).

It was observed that TP concentration in the supernatant was significantly increased after acidic pretreatment (from 7.02 mg/L to 57.15 mg/L) (Fig. 1). Sludge contains some amount of phosphours precipitates which would dissociate at low pH condition. Hence, the TP increase was observed in the liquid phase after acidic pretreatment. As mentioned, cell lysis occurs after alkaline treatment. However, at high pH, PO₄³⁻ could form precipitate and stay in solid phase. Thus, it leads to the lower TP concentration in the supernantant of alkaline treated sludge compared to that of acidic treatment. Among all, ultrasonication was still the best one for releasing TP (from 7.02 mg/L to 84 mg/L) (Fig. 1).

Overall, ultrasonication was the most efficient method on the release of SCOD, TN and TP. Similar results were reported that SCOD, TP, TN in the supernatant of sludge were significantly increased after ultrasonication pretreatment (Kim et al., 2013; Pei et al., 2015). Other pretreatment methods also had some merits on releasing certain nutrients, for instance, acidic pretreatment on the release of TP, alkaline pretreatment on the release of TN. Further studies could be carried out on the combination of ultrasonication and acidic pretreatment or ultrasonication and alkaline pretreatment in order to enhance the release of targeted nutrients.

Sludge pretreatments on lipid production and nutrient utilization

Due to pretreatment, some suspended solids are dissolved into soluable form, hence, decrease of MLSS was observed after treatments. The obtained MLSS after sludge pretreatment was the initial MLSS of the fermentation. The results are shown in Fig. 2.

It was observed that the MLSS concentration first increased and then decreased in all the cases (Fig. 2). The increase started after 12 h fermentation in the case of control, acid and alkaline treatmented sludge. For microwave and ultrasonication pretreatment cases, the MLSS increase lasted till 24 h and 60 h, respectively. After increasing stage, MLSS gradually decreased in the systems. The increase on MLSS was mainly due to: the inoculation of pre-culture; the biomass growth by consuming the left substrate from pre-cultrue medium; the biomass growth by consuming the SCOD in the medium.

In the fermentation with original sludge, acid or alkaline treated sludge, the available SCOD is very limited (Fig. 1). It is not able to contribute to the biomass growth, hence MLSS increase would be mainly due to the addition of preculture. After the left substrate from preculture medium is finished, microorganisms start to degrade the organic matters in the sludge. The microorganism biomass increases but sludge amount (organic matter decomposition) is decreasing, and the increase is smaller than the decrease as part of the organic matters are emitted in the form of carbon dioxide. Thus, the observed MLSS is in decrease trend. It is similar as aerobic digestion in which significant sludge reduction occurs due to the microorganism growth (Liu et al., 2017; Shao et al., 2013).

In the fermentation with microwave and ultrasonication treated sludge, the intial SCOD concentration was high (Fig. 2). During fermention, the microorganisms consumed SCOD for self growth which led to the gradual SCOD decrease and MLSS increase. After SCOD was finished, the MLSS started to drop. At the end of the fermentation, the MLSS was in the order of ultrasonication (3.71 ± 0.24 g/L) < microwave (4.70 ± 0.08 g/L) < alkaline (4.81 ± 0.31 g/L) < acid (5.54 ± 0.22 g/L) < control (5.89 ± 0.47 g/L). It suggests that still great amount of available organic matters remains undegraded in the sludge medium prepared with original sludge, acid, alkaline, and microwave pretreated sludge.

It was observed that lipid content gradually increased until a maximum lipid content was obtained at 48 h (microwave and ultrasonication) or 60 h (control, acid and alkaline) of the fermentation (Fig. 2). Ultrasonication pretreated sludge medium contained the highest bioaviable materials (SCOD) among all (Fig. 2), and correspondingly the highest lipid content (36.67% g/g) was obtained in the fermentation with ultrasonication pretreatment sludge (Fig. 2). However, it is still largely lower than the strain lipid accumulation potential (up to 70% g/g). The common explanation was that oleaginous yeast achieved high lipid accumulation in carbon rich and nitrogen depletion conditions. The carbon source in the raw sludge was not sufficient to support oleaginous yeast to produce high lipid content even after the pretreatments (Zhang et al., 2014c). In order to achieve high lipid production, the promising solution was to fortify the sludge by mixing sludge with other carbon rich substrates (Zhang et al., 2018). Our previous studies proved that the lipid content increased from 35% g/g while using solo pretreated sludge medium to 50% g/g after addition of crude glycerol to the pretreated sludge (Zhang et al., 2018; Zhang et al., 2014c). Due to the depletion of substrates, lipid content gradually decreased till the end of the fermentation (Fig. 2). It would be due to the microorganism self consumption in lipid for supplying energy to cell activities.

It was found that SCOD rapidly dropped during lipid accumulation period in the fermentation with ultrasonication pretreated sludge, which indicates the fast consumption of substrate by oleaginous yeast (Fig. 2e). Our previous study found that the consumption of substrates in the initial stage was due to the fast cell growth and thereafter was mainly due to the lipid production (Chen et al., 2017). After 60 h, the depletion of SCOD was observed which caused the fast decrease of lipid content (Fig. 2e) (Chen et al., 2017).

At the end of the fermentations, TN concentration reduced (Fig. 3). The reduction of nitrogen concentration in the supernatant was owing to the formation of the intracellular material of the strain such as protein. Compared to carbon, nitrogen needed for cell growth was much less (Gupta et al., 2019). Thus, the utilization amount of nitrogen concentration was less than SCOD amount. The highest TN consumption occurred in fermentation with ultrasonication pretreated sludge (Fig. 3), which is due to the better biomass growth in this case compared to others (Fig. 2e).

Sludge valorization and reduction

Lipid extracted from biomass obtained in the fermentation with ultrasonication pretreated sludge was transesterified to biodiesel (fatty acid methyl esters). The composition was shown in Fig. 4. It was found that the fractions of C16:0, C17:0, C18:0 and C18:2 continuously increased during the fermentation. Among all, C18:2 was the principal composition (46.17%). The esters with carbon chain of C14 to C20 were similar as plant seed oils which is currently using for commercial biodiesel production. Therefore, using ultrasonication pretreated sludge for biodiesel production was applicable.

Sludge reduction is an important target in sludge management. In this study, the sludge reduction due to the lipid production was calculated according to the difference of the initial MLSS of the fermentation and the final solid mass after extraction. The maximum sludge reduction occurred in the fermentation with ultrasonication pretreated sludge which was 63.10%, followed by microwave (43.03%), alkaline (36.44%) and acidic (32.59%).

Solo ultrasonication and its combination with other pretreatment have also been used for methane and hydrogen production. The sludge reduction in different process was compared (Table 1), and it was found that using ultrasonication pretreated sludge for lipid production achieved remarkable sludge reduction in short time. It was reported that ultrasonication combined with other pretreatment methods had certain advantages on nutrient release and enhancement on sludge reduction (Geng et al., 2016; Ma et al., 2012; Niu et al., 2019). Further study might be performed on the investigation of untrasonication combined with other pretreatment methods for improving lipid production and sludge reduction.

Table 1

Comparison of sludge reduction after ultrasonication pre-treatment using different method
Pretreatment	Sludge reduction method	Duration (days)	Sludge reduction (%)	Ref.
Alkaline-ultrasonic pretreatment	Methane production	25	28.68%	(Geng et al., 2016)
Ultrasonic pretreatment	Anaerobic digestion	30	23.7%	(Lizama et al., 2018)
Ultrasonic and free nitrous acid pretreatment	Hydrogen production	3	33.6%	(Niu et al., 2019)
Alkaline-ultrasonic pretreatment	Lysis-cryptic growth	12	56.5%	(Ma et al., 2012)
Ultrasonication	Aerobic digestion	3	40.2%	(Kavitha et al., 2016)
Ultrasonication	Lipid production	2	63.10%	This study

Pretreatment is essencial for dissociation of complex materials in sludge. It was found that ultrasonication was more efficient for the release of SCOD, TN and TP compared to acdic, alkaline, and microwave treatment from this study. The high release of SCOD from ultrasonication treatment leads to its promising potential as pretreatment of biological sludge management. Combination of ultrasonication with other treatment would provide better performance and related study is demanded.

Materials

Sewage sludge

In this study, the raw secondary wastewater sludge was collected from a municipal wastewater treatment plant located in Shenzhen, China. After collection, the sewage sludge was covered and stored at 4 ºC.

Strain

The lipid producing strain was oleaginous yeast Lipomyces starkey which was purchased from China Center of Industrial Culture Collection (CICC).

Pre-culture medium

The pre-culture medium was prepared with Yeast Extract Peptone Dextrose Medium (YPD) (20 g/L glucose, 20 g/L peptone and 10 g/L yeast extract).

Fermenter

In this study, the experiments were carried out in a 5 L fermenter(Blbio-5G)with a working volume of 3.5 L. The pH, dissolved oxygen (DO), agitation and temperature were automatically controlled during the fermentation.

Experiments

Sludge characterization

One liter sludge was directly used to determine the mixed liquor suspended solids (MLSS) and mixed liquor volatile suspended solids (MLVSS) after transported to lab from the treatment plant.

To analysis MLSS, a quantitative membrane filter paper was dried at 105 ºC until weight (M₁) was constant. Then 50 ml of sludge was filtered with the pre-dried filter paper. After filtration, the filtrate was used to determine the total nitrogen (TN), total phosphorus (TP) and soluable chemical oxygen demand (SCOD). The filter containing soild was dried at 105 ºC till wight constant. The total weight of the dired solid and filter paper was noted as M₂. The MLSS was calculated based on Eq. 1.

MLSS=(M₂–M₁)/0.05 (g/L) (1)

The filter paper obtained from MLSS analysis was then used for the determination of MLVSS. The filter paper with the dry solid was transferred to a pre-weighed ceramic crucible (M₃). Then the crucible was put in a muffle furnace at 600 ºC for 60 min. After cooling down, the crucible was weighted (M₄). MLVSS was calculated according to Eq. 2

MLVSS=[(M₂-M₁)–(M₄-M₃)]/0.05 (2)

The property of raw sludge utilized in the study was shown in Table 2.

Table 2

The properties of sludge and filtrate
Properties	Sources	Value
MLSS (g/L)	Sludge solution	7.14 ± 0.69
MLVSS (g/L)	Sludge solution	4.61 ± 0.22
TN (mg/L)	Filtrate	40.50 ± 3.43
TP (mg/L)	Filtrate	7.02 ± 0.30
pH	Sludge solution	7.3
SCOD (mg/L)	Filtrate	32.64 ± 5.19

Sludge pretreatment

Acid or base pretreatment

The 5 mol/L of H₂SO₄ solution or NaOH solution was used to adjust the pH of the 4 L sludge soultion to 2 or 12. Due to the buffering nature of sludge, several adjustments were performed till the pH was stable at 2 or 12. Then the sludge solution was stirred for 2 h followed by centrifugation. The supernatants were collected for the measurement of SCOD, TN and TP.

Microwave irradiation

In each run, plate filled with 1 L sludge solution was microwaved for 15 min. During the microwave irradiation, the sludge solution was mixed with a 5 min interval. The obtained solutions were well mixed perior to being used for fermentation.

Ultrasonication

The ultrasonication was achieved by placing the sonication probe in the 2 L beaker containing 0.5 L of sludge solution. The ultrasonication was conducted for 30 min at 450 W and 20 kHz frequency. Ultrasonication was operated with 5 s on and 2 s off mode. The temperature of the sludge was not controlled during ultrasonication. The obtained solutions were employed as medium of oleaginous yeast fermentation.

Fermentation

The preculture was obtained by inoculating a loop full of Lipomyces starkey to 350 mL sterilized YPD medium and then incubated at 28 ℃ and 150 rpm for 24 h. Then the 350 mL preculture was transferred to the 5 L fermenter with 3.15 L sludge medium. The sludge medium was the whole sludge (solid and liquid) collected from the acidic, alkaline, microwave, or ultrasonication pretreatment after adjustmenting the pH to around 5.5.

During fermentation, DO was miantained above 30% (v/v) by controlling the agitation and aeration rate. The temperature was kept at around 28 °C. The pH was not controlled during the whole fermentation. Samples (50 mL) were taken at every 12 h during fermentation for analysis.

Analysis

In this study, biomass referred to the MLSS in the fermentation broth. Thus, it was measured as stated above. To determine lipid, a 10 mL sample was centrifuged at 6500 rpm for 15 min. After discard of the supernatant, the remaining solids were dried at 80 °C for 24 h. The dry solids were transferred to 50 mL solvent-proof tubes. Then 30 mL of the mixture of chloroform and methanol (2:1 v/v) and 6 mL Zirconia beads (1 mm diameter) were added into the tube and then continuously shaken for 12 h in a wrist action shaker. After centrifugation, the bottom layer solution was withdrawn and filtered. The filtrate was put into a pre-weighed glass tube. After evaporation, the weight difference of the glass tube was the lipid in the 0.01 L sample. Lipid content was calculated according to Eq. 3

Lipid content (% w/w) = lipid concentration/biomass concentration (3)

To estimate the potential of the lipid for biodiesel production, the extracted lipid was reacted with a mixture of H₂SO₄ and methanol (H₂SO₄/CH₄OH = 1% v/v) at 60 °C for 12 h. The molar ratio of methanol to lipid was set at 6:1. Fatty acid methyl esters (FAMEs, biodiesel) were obtained and extracted with hexane. The composition of biodiesel FAMEs was analyzed using Gas Chromatography linked to Mass Spectroscopy (GC-MS) (Zhang et al., 2014a).

All analysis was duplicated. The results presented in this study were the avaerge value. The standard deviations are less than 5%.

Ethics approval and consent to participate: Not applicable.

Consent for publication: Not applicable.

Availability of data and material: Data sharing not applicable to this article as no datasets were generated or analysed during the current study.

Competing interests: The authors declare that they have no competing interests.

Funding: This work was supported by the STU Scientific Research Foundation for Talents (140-09419031), Shenzhen Scientific Research Foundation for High-level Talent (Grant number KQJSCX20180328165658476), Shenzhen Scientific Fundamental Research Foundation (Grant number JCYJ20180306171843211 and JCYJ20180306172051662). The role of the funding bodies is the design of the study.

Authors' contributions: CJX designed and performed the experiments, analyzed samples, and prepared the manuscript. LJ directed the experiment direction and provided suggestions while encountering problems. ZXL did review on biodiesel production from wastewater sludge and interpreted the obtained results, revised the manuscript. WZY performed the experiment and sample analysis. All authors read and approved the final manuscript.

Acknowledgement: authors would like give sincerely thanks to Shantou University, Shenzhen Science and Technology Innovation Commision, Harbin Institute of Technology (Shenzhen) for their support to provide lab, equipments, and materials.

Ahmad T, Ahmad K, Alam M. Sustainable management of water treatment sludge through 3‘R’ concept. J Clean Prod. 2016;124:1–13.
Brémond U, de Buyer R, Steyer J-P, Bernet N, Carrere H. Biological pretreatments of biomass for improving biogas production: an overview from lab scale to full-scale. Renew Sustain Energy Rev. 2018;90:583–604.
Carrère H, Dumas C, Battimelli A, Batstone DJ, Delgenès JP, Steyer JP, Ferrer I. Pretreatment methods to improve sludge anaerobic degradability: A review. J Hazard Mater. 2010;183(1):1–15.
Černe M, Palčić I, Pasković I, Major N, Romić M, Filipović V, Igrc MD, Perčin A, Ban G, Zorko S, Vodenik B, Glavič B, Cindro D, Milačič R, Heath DJ, Ban D. The effect of stabilization on the utilization of municipal sewage sludge as a soil amendment. Waste Manag. 2019;94:27–38.
Chanaka Udayanga WD, Veksha A, Giannis A, Lisak G, Lim T-T. Effects of sewage sludge organic and inorganic constituents on the properties of pyrolysis products. Energy Convers Manag. 2019;196:1410–9.
Chen J, Tyagi RD, Li J, Zhang X, Drogui P, Sun F. Economic assessment of biodiesel production from wastewater sludge. Biores Technol. 2018;253:41–8.
Chen J, Zhang X, Yan S, Tyagi RD, Drogui P. Lipid production from fed-batch fermentation of crude glycerol directed by the kinetic study of batch fermentations. Fuel. 2017;209:1–9.
Ekblad M, Falås P, El-taliawy H, Nilsson F, Bester K, Hagman M, Cimbritz M. Is dissolved COD a suitable design parameter for ozone oxidation of organic micropollutants in wastewater? Science of The Total Environment. 2019;658:449–56.
Geng Y, Zhang B, Du L, Tang Z, Li Q, Zhou Z, Yin X. Improving Methane Production During the Anaerobic Digestion of Waste Activated Sludge: Cao-ultrasonic Pretreatment and Using Different Seed Sludges. Procedia Environmental Sciences. 2016;31:743–52.
Gherghel A, Teodosiu C, De Gisi S. A review on wastewater sludge valorisation and its challenges in the context of circular economy. J Clean Prod. 2019;228:244–63.
Grobelak A, Czerwińska K, Murtaś A. 2019. 7 - General considerations on sludge disposal, industrial and municipal sludge. in: Industrial and Municipal Sludge, editors M.N.V. Prasad, P.J. de Campos Favas, M. Vithanage, S.V. Mohan, Butterworth-Heinemann, pp. 135–153.
Grönroos A, Kyllönen H, Korpijärvi K, Pirkonen P, Paavola T, Jokela J, Rintala J. Ultrasound assisted method to increase soluble chemical oxygen demand (SCOD) of sewage sludge for digestion. Ultrason Sonochem. 2005;12(1):115–20.
Gupta N, Khare P, Singh DP. Nitrogen-dependent metabolic regulation of lipid production in microalga Scenedesmus vacuolatus. Ecotoxicol Environ Saf. 2019;174:706–13.
Harris PW, McCabe BK. Review of pre-treatments used in anaerobic digestion and their potential application in high-fat cattle slaughterhouse wastewater. Appl Energy. 2015;155:560–75.
Kavitha S, Jessin Brindha GM, Sally Gloriana A, Rajashankar K, Yeom IT, Banu R, J. Enhancement of aerobic biodegradability potential of municipal waste activated sludge by ultrasonic aided bacterial disintegration. Biores Technol. 2016;200:161–9.
Kidak R, Wilhelm A-M, Delmas H. Effect of process parameters on the energy requirement in ultrasonical treatment of waste sludge. Chem Eng Process. 2009;48(8):1346–52.
Kim D-H, Cho S-K, Lee M-K, Kim M-S. Increased solubilization of excess sludge does not always result in enhanced anaerobic digestion efficiency. Biores Technol. 2013;143:660–4.
Kor-Bicakci G, Eskicioglu C. Recent developments on thermal municipal sludge pretreatment technologies for enhanced anaerobic digestion. Renew Sustain Energy Rev. 2019;110:423–43.
Li X, Peng Y, He Y, Jia F, Wang S, Guo S. Applying low frequency ultrasound on different biological nitrogen activated sludge types: An analysis of particle size reduction, soluble chemical oxygen demand (SCOD) and ammonia release. International Biodeterioration Biodegradation. 2016;112:42–50.
Liu Y, Gao M, Zhang A, Liu Z. Strengthen effects of dominant strains on aerobic digestion and stabilization of the residual sludge. Biores Technol. 2017;235:202–10.
Lizama AC, Figueiras CC, Pedreguera AZ, Ruiz Espinoza JE. Effect of ultrasonic pretreatment on the semicontinuous anaerobic digestion of waste activated sludge with increasing loading rates. International Biodeterioration Biodegradation. 2018;130:32–9.
Ma H, Zhang S, Lu X, Xi B, Guo X, Wang H, Duan J. Excess sludge reduction using pilot-scale lysis-cryptic growth system integrated ultrasonic/alkaline disintegration and hydrolysis/acidogenesis pretreatment. Biores Technol. 2012;116:441–7.
Mehrdadi N, Kootenaei FG. An investigation on effect of ultrasound waves on sludge treatment. Energy Procedia. 2018;153:325–9.
Niu Q, Xu Q, Wang Y, Wang D, Liu X, Liu Y, Wang Q, Ni B-J, Yang Q, Li X, Li H. Enhanced hydrogen accumulation from waste activated sludge by combining ultrasonic and free nitrous acid pretreatment: Performance, mechanism, and implication. Biores Technol. 2019;285:121363.
Paolini V, Petracchini F, Carnevale M, Gallucci F, Perilli M, Esposito G, Segreto M, Occulti LG, Scaglione D, Ianniello A, Frattoni M. Characterisation and cleaning of biogas from sewage sludge for biomethane production. J Environ Manage. 2018;217:288–96.
Pei J, Yao H, Wang H, Shan D, Jiang Y, Ma L, Yu X. Effect of ultrasonic and ozone pre-treatments on pharmaceutical waste activated sludge’s solubilisation, reduction, anaerobic biodegradability and acute biological toxicity. Biores Technol. 2015;192:418–23.
Pilli S, Bhunia P, Yan S, LeBlanc RJ, Tyagi RD, Surampalli RY. Ultrasonic pretreatment of sludge: A review. Ultrason Sonochem. 2011;18(1):1–18.
Pilli S, Yan S, Tyagi RD, Surampalli RY. Overview of Fenton pre-treatment of sludge aiming to enhance anaerobic digestion. Reviews in Environmental Science Bio/Technology. 2015;14(3):453–72.
Qian L, Wang S, Xu D, Guo Y, Tang X, Wang L. Treatment of municipal sewage sludge in supercritical water: A review. Water Res. 2016;89:118–31.
Raheem A, Sikarwar VS, He J, Dastyar W, Dionysiou DD, Wang W, Zhao M. Opportunities and challenges in sustainable treatment and resource reuse of sewage sludge: A review. Chem Eng J. 2018;337:616–41.
Revellame ED, Hernandez R, French WT, Holmes WE, Forks A, Ii C, R. Lipid-enhancement of activated sludges obtained from conventional activated sludge and oxidation ditch processes. Biores Technol. 2013;148:487–93.
Rodriguez C, Alaswad A, Mooney J, Prescott T, Olabi AG. Pre-treatment techniques used for anaerobic digestion of algae. Fuel Process Technol. 2015;138:765–79.
Shao L, Wang T, Li T, Lü F, He P. Comparison of sludge digestion under aerobic and anaerobic conditions with a focus on the degradation of proteins at mesophilic temperature. Biores Technol. 2013;140:131–7.
Shin D-c, Kim J-s, Park C-h. Study on physical and chemical characteristics of microorganism immobilized media for advanced wastewater treatment. Journal of Water Process Engineering. 2019;29:100784.
Siddiquee MN, Rohani S. Experimental analysis of lipid extraction and biodiesel production from wastewater sludge. Fuel Process Technol. 2011;92(12):2241–51.
Wang F, Wang Y, Ji M. Mechanisms and kinetics models for ultrasonic waste activated sludge disintegration. J Hazard Mater. 2005;123(1):145–50.
Wang Q. Achieving Stable Nitritation for Mainstream Deammonification by Combining Free Nitrous Acid-Based Sludge Treatment and Oxygen Limitation. Sci Rep. 2016;6:25547.
Wang Z, Wang B, Gong X, Qiao X, Peng Y. Free nitrous acid pretreatment of sludge to achieve nitritation: The effect of sludge concentration. Biores Technol. 2019;285:121358.
Yang G, Zhang G, Wang H. Current state of sludge production, management, treatment and disposal in China. Water Res. 2015;78:60–73.
Yu G, Peng H, Fu Y, Yan X, Du C, Chen H. Enhanced nitrogen removal of low C/N wastewater in constructed wetlands with co-immobilizing solid carbon source and denitrifying bacteria. Biores Technol. 2019;280:337–44.
Zhang G, Yang J, Liu H, Zhang J. Sludge ozonation: Disintegration, supernatant changes and mechanisms. Biores Technol. 2009;100(3):1505–9.
Zhang Q, Hu J, Lee D-J, Chang Y, Lee Y-J. Sludge treatment: Current research trends. Biores Technol. 2017;243:1159–72.
Zhang X, Chen J, Idossou V, Tyagi RD, Li J, Wang H. Lipid accumulation from Trichosporon oleaginosus with co-fermentation of washed wastewater sludge and crude glycerol. Fuel. 2018;226:93–102.
Zhang X, Yan S, Tyagi RD, Drogui P, Surampalli RY. Ultrasonication assisted lipid extraction from oleaginous microorganisms. Biores Technol. 2014a;158:253–61.
Zhang X, Yan S, Tyagi RD, Surampalli R, Valéro JR. Wastewater sludge as raw material for microbial oils production. Appl Energy. 2014b;135:192–201.
Zhang X, Yan S, Tyagi RD, Surampalli RY. Energy balance and greenhouse gas emissions of biodiesel production from oil derived from wastewater and wastewater sludge. Renewable Energy. 2013;55:392–403.
Zhang X, Yan S, Tyagi RD, Surampalli RY, Valéro JR. Lipid production from Trichosporon oleaginosus cultivated with pre-treated secondary wastewater sludge. Fuel. 2014c;134:274–82.
Zhu F, Wu X, Zhao L, Liu X, Qi J, Wang X, Wang J. Lipid profiling in sewage sludge. Water Res. 2017;116:149–58.

Download PDF

Journal Publication

published 14 Dec, 2020

Read the published version in Biotechnology for Biofuels and Bioproducts →

Editorial decision: Major revision
07 Oct, 2020
Review #1 received at journal
23 Sep, 2020
Review #2 received at journal
23 Sep, 2020
Review #3 received at journal
23 Sep, 2020
Reviewers invited by journal
17 Sep, 2020
Reviewer #1 agreed at journal
17 Sep, 2020
Reviewer #2 agreed at journal
17 Sep, 2020
Reviewer #3 agreed at journal
17 Sep, 2020
Editor assigned by journal
12 Aug, 2020
First submitted to journal
11 Aug, 2020
Submission checks completed at journal
11 Aug, 2020
Editor invited by journal
11 Aug, 2020

You are reading this older preprint version

Read the latest preprint version →

Pretreatments for Enhancing Sewage Sludge Reduction and Reuse in Lipid Production

Status:

Journal Publication

Version 1

Abstract

Figures

Background

Results And Discussion

Pretreatment impact on SCOD and nutrients release from sludge

Sludge pretreatments on lipid production and nutrient utilization

Sludge valorization and reduction

Conclusions

Methods

Materials

Experiments

MLVSS=[(M₂-M₁)–(M₄-M₃)]/0.05 (2)

Analysis

Declarations

References

Status:

Journal Publication

Version 1

Pretreatments for Enhancing Sewage Sludge Reduction and Reuse in Lipid Production

Status:

Journal Publication

Version 1

Abstract

Figures

Background

Results And Discussion

Pretreatment impact on SCOD and nutrients release from sludge

Sludge pretreatments on lipid production and nutrient utilization

Sludge valorization and reduction

Conclusions

Methods

Materials

Experiments

MLVSS=[(M2-M1)–(M4-M3)]/0.05 (2)

Analysis

Declarations

References

Status:

Journal Publication

Version 1

MLVSS=[(M₂-M₁)–(M₄-M₃)]/0.05 (2)