Next Article in Journal
AUSTRET: An Automated Step Response Testing Tool for Building Automation and Control Systems
Next Article in Special Issue
Land-Use Change and Bioenergy Production: Soil Consumption and Characterization of Anaerobic Digestion Plants
Previous Article in Journal
FEHCA: A Fault-Tolerant Energy-Efficient Hierarchical Clustering Algorithm for Wireless Sensor Networks
Previous Article in Special Issue
Size-Segregated Particulate Matter from Gasification of Bulgarian Agro-Forest Biomass Residue
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Energies
Volume 14
Issue 13
10.3390/en14133971
energies-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Separate Collected Versus Mechanical Segregated Organic Fractions in Terms of Fertilizers Suitability

by
Przemysław Seruga
1,* and
Małgorzata Krzywonos
2
1
Department of Bioprocess Engineering, Wroclaw University of Economics and Business, Komandorska 118/120, 53-345 Wrocław, Poland
2
Department of Process Management, Wroclaw University of Economics and Business, Komandorska 118/120, 53-345 Wrocław, Poland
*
Author to whom correspondence should be addressed.
Energies 2021, 14(13), 3971; https://doi.org/10.3390/en14133971
Submission received: 13 May 2021 / Revised: 20 June 2021 / Accepted: 29 June 2021 / Published: 2 July 2021
(This article belongs to the Special Issue Sustainable and Circular Systems for Biofuel Production and Usage)
Browse Figure
Versions Notes

Abstract

:
Nowadays, municipal solid waste (MSW) management is one of the most critical issues. MSW may threaten the environment; however, the concerning high organic fraction content can be useful. This study aimed to compare the suitability of mechanically sorted organic fraction (OF) of MSW and source-segregated biowaste for biofertilizer usage. The compost and the effluents compositions were analyzed. Compost derived from biowaste can be applied to the soil, while, after processing OFMSW, the metal contents are too high. The exceeding limit values were noted, e.g., lead (over 80 mg/kg) and chrome (75 mg/kg). Effluents from biowaste treatment fulfill the national and UE fertilizers’ requirements, considering the heavy metal contents, while effluents from OFMSW treatments exceed the limit values. The biggest exceedings were observed for nickel (over 3 mg/kg) and zinc (over 500 mg/kg). In general, the heavy metal contamination of byproducts from the OFMSW treatment was much higher. At the same time, the biogenic elements, e.g., nitrogen and phosphorus concentrations, were much lower than the biowaste treatment byproducts; however, even for them, the concentrations of the biogenic elements were too low to meet EU requirements. The compost and effluents derived from the biowaste treatment may be suitable for crop applications, considering the current national requirements.

1. Introduction

Urbanization, rising living standards, and the expanding population affect the increment in the quantity of municipal solid waste (MSW) [1,2]. Yearly, the global generation of MSW is at the level of 2.01 billion tons [3], and its further increase is expected, even by 70% (to 3.4 billion tons) by 2050 [4]. Thus, MSW management remains a critical concern of the present and future, considering environmental protection and sustainability.
MSW can affect the environment by the emission of leachate, greenhouse gases, or odors. On the other hand, due to the organic fraction content (40–50%) [5], MSW can be valuable material. For the MSW treatment (mainly the organic fraction of municipal solid waste (OFMSW)), various methods have been applied to reduce landfilling, which is incompatible with current tendencies (e.g., circular economy, zero waste) [1]. For example, biological (anaerobic digestion [6] and composting [5]) and thermochemical (gasification [7] and hydrothermal [8]) treatments [9] have been used. Among the developed treatment pathways, anaerobic digestion (AD) has received more adherents worldwide [3,10]. The AD allows for energy recovery and organic matter decomposition. Thus, except for biogas generation improvement, biofertilizer production has to be still widely investigated, mainly in cooperation with existing facilities, which is limited.
There are around 18,000 biogas plants in Europe [11], using agriculture, food waste, and the OFMSW as feedstock. The OFMSW is generally an effect of the mechanical sorting of mixed solid waste. Source-segregated and collected separately from inhabitants, organic fractions can be defined as biowaste. In the analyzed area, it was a “door-to-door” system regarding rural and single-family housing, with the assumption of disposal in various standard bins in the case of multi-family housing. The OFMSW is generated in the mechanical sorting and separation process performed in mechanical–biological treatment (MBT) plants [12]. Source segregation fits the circular economy concept and is regarded as a landfilling problem solution [12]. Source-segregated biowaste provides higher recovery potential and treatment process performance compared to OFMSW [13]. Nevertheless, the biological treatment of OFMSW still has to be verified, mainly in full-scale, considering that also generated byproducts.
In full-scale AD plants, a wide variety of biowaste is used to produce biogas, i.e., biological household waste, food waste, OFMSW, sewage, and biowaste [6]. The two main byproducts: the digestate (semi-solid residue) and the effluents (together with liquid digestate) occur from AD and must be adequately managed. The digested residue might be used as a fertilizer and must, therefore, be hygienically safe [14]. The AD might also be followed by composting. Composting is a natural process conducted in aerobic conditions, leading to partial mineralization and biomass humification [15]. In Europe, nearly 95% of the produced digestate can be used as an organic fertilizer to replace chemically produced fertilizers [16]. Thus, it is crucial to ensure the quality of the fertilizers. Furthermore, the reviewed literature focused on the digestate from agricultural raw materials (manure, slurry, and energy crops); only a minor part concern with digestate derived from the urban feedstock, i.e., OFMSW. Therefore, the highlights of possible differences between digestate and effluents from OFMSW and biowaste are still missing.
The reviewed literature indicates that AD has the best environmental and economic fulfillment amid organic waste various biological treatment options [9]. However, it should be mentioned that attention should be paid to process efficiency (biogas yield) and performance (stability), together with the possibility of reusing byproduct (digestate, compost, and effluents). Meanwhile, most of the currently published studies are focused only on the biogas yield. Furthermore, the literature is scarce on the overall AD analysis, considering the mentioned issues, especially in full-scale. Moreover, the comparison of separately collected biowaste and OFMSW should be performed to define source segregation benefits, which is more absorbing for people.
Annually, around 56 × 106 tons of digestate is generated in Europe; consequently, digestate management becomes a major concern for plant operators and policymakers [17]. Currently, regarding digestate, the effluents and compost requirements to usage as the fertilizer and end-of-waste criteria are defined by different countries and on different levels [17,18]. In the middle of 2019, the European Parliament released the regulation, which defines the CE marking rules [19]. The manufacturer indicates that the EU fertilizing product conforms with the applicable requirements set out in Union harmonization legislation, providing for its affixing. However, the rules will apply with some delay. For instance, due to Poland, the starting date is 16 July 2022. Thus, the comparison of current applied requirements with the future is crucial.
This study aimed to compare the suitability of OFMSW and separately collected biowaste for biofertilizer usage. The compost derived from both organic waste streams AD and the effluents compositions were analyzed. The research was performed on a full scale, using an operating plant. The source segregation fits with current trends and is considered to be the right path towards zero waste. This comparison complements the analysis of selective municipal waste collection benefits, considering anaerobic digestion and its byproduct usage possibility. Furthermore, the EU requirements should be the target for countries; thus, it is important to get to know the current status and have some time for improvements.

2. Materials and Methods

2.1. The Full-Scale Research

The research was performed at the MBT Plant (ZGO Gać), located in the Lower Silesia region (Oława, Poland). The plant processes around 65,000 tons of MSW per year and around 14,000 tons of separately collected biowaste (such as food waste, kitchen waste, and green waste). A simplified diagram of the biological treatment installation is presented in Figure 1.
Both waste streams are processed via anaerobic digestion (AD) at the plant. The AD facility consists of two Kompogas® chambers, operating in thermophilic conditions (54 °C) [13]. After the fermentation, waste was removed from the chamber using a piston pump. Then, the digestate was dewatered using screw presses (TSP350, Thöni, Austria). Next, the effluents were collected in a storage tank (200 m3) and characterized, considering fertilizer usage. Finally, the solid digestate was composted.
The composting process was performed in an enclosed reactor (pile size 21.5 m × 7.5 m × 2.0 m) with positive aeration (fresh air flow of 60.5 m3/min) to ensure oxygen within the pore spaces inside the pile more than 5%. The temperature was measured by a stainless temperature probe (2 m long) to control the process. Proper porosity was ensured by adding 30% of structuring material. After three weeks, composting was continued on an open maturation field for eight weeks. Finally, the 20-mm grain size compost was generated using the trommel (MPB 18.47, Pronar, Narew, Poland).

2.2. Analytical Methods

The feedstock samples were collected over a month. First, the daily sample was prepared by collecting 10–15-kg samples at about 60 min. intervals. Then, the daily samples collected over a week were mixed and averaged to get one weekly sample of OFMSW and one weekly sample of biowaste of approx. 100 kg each. The determination of the composition, including 11 main material fractions: organic, wood, paper, plastics, glass, metals, textiles, multi-material, inert, hazardous, and others of a fine fraction, was verified. Finally, the average values based on the weekly samples were reported.
The chemical analyses were conducted on dried samples at 105 °C for 12 h. Three samples of each material were analyzed. Average values were reported.
The loss-on-ignition (LOI) test was used to determine organic matter (OM) in biofertilizers. The samples were subjected to dry combustion for six hours at a temperature of 550 °C. The total organic carbon (TOC) and nitrogen (N) contents were determined using a Vario Max CNS elemental analyser (Elementar Analysensysteme GmbH, Langenselbold, Germany). The amounts of metals in the sample were determined after the sample’s calcination at 450 °C for six hours. The ash was dissolved in 5 mL of 6-mol × dm3 HCl and diluted to a constant volume with distilled water [20]. The obtained extracts were analyzed to determine the amounts of potassium (K), zinc (Zn), copper (Cu), nickel (Ni), lead (Pb), and cadmium (Cd) using atomic absorption spectrophotometry in a Varian Spectra AA 220 FS apparatus (Varian Inc., Palo Alto, CA, USA). The total phosphorus (P) content was measured colorimetrically by the vanadium–molybdenum method [20].
Dry matter was measured gravimetrically after drying a 200-g sample for 24 h at 105 °C.
The pH value was determined in polyethylene bottles (1000 mL) filled with 400 mL of deionized water. Samples were added up to a volume of 600 mL and extracted for one hour. Immediately after extraction, the pH was determined in the substrate water suspension (Hach HQ40d, Düsseldorf, Germany).

3. Results and Discussion

The AD input materials characteristics are presented in Table 1. The fraction contents were similar to the results obtained in our previous study [13]. It was noticed that the organic content was higher in biowaste (67.2%) compared to OFMSW (46.3%), while the wood quantity was at a similar level (7.4 and 6.2%, respectively). The fine fraction content was about 13% higher in OFMSW, which can be explained by the coal ashes typical of Poland. Furthermore, the presence of paper, plastics, glass, inert, and other fractions may indicate insufficient sources of segregation.
The comparison of the produced compost originated from OFMSW and biowaste and organic fertilizers requirements is presented in Table 2. The liquid fraction (effluents) was analyzed as the liquid fertilizer (Table 3).
The quality of the soil improvers, determined by several indicators, is crucial for the potential usage of waste treatment residues. The amendments must contain the organic matter (OM) appropriate content to enrich the soil [23]. The OM of ss-compost reached about 31.5% of dry matter (DM) and was 3.5% higher than the ms-compost and fulfilled the required levels (Table 2). The obtained values were similar to those reported by Teglia et al. 2011 for the post-composted digestate of organic waste (kitchen waste (15%), garden waste (75%), paper, and cardboard (10%), where a 38.6% OM content was established [23]. Regarding the liquid residues examined in this study, the OM was higher than for solid ones. The ms-effluents were characterized by a 34% OM content, followed by 43.4% for the ss-effluents. However, it was still a lower value than reported by Teglia et al. for wastewater treatment sludges [23]. Depending on the proportion of the primary (33% and 60%) and activated (65% and 40%) sludges, the OM content reached 56.7% and 59.9%, respectively [23].
The digestion residues characterize different DM, which is related to the feedstock and post-treatment process. Stürmer et al. (2020) analyzed over 560 test results of Austrian digestates, mainly agricultural. The reported DM content was, on average, 8.18% [18], which was similar to French digestate characteristics [24] but lower when compared to an Italian study (12.7% for agricultural waste) [17]. The effluents examined in this study were characterized by 21.6% and 13.6% of DM for ms- and ss-effluents, respectively (Table 3). The reason for this might be higher mineral and fine fraction contents in the mechanical sorted organic fraction of municipal solid waste [13]. The DM content affects the stickiness and viscosity. It was found that the DM content around 20% appeared too high to be easily used directly [23]. The moisture can affect higher transport costs, storage difficulties, and distribution problems. Thus, the liquid residues should be directly spread on soils in a local area. When intended for transport, distribution should be solid amendments. In the case of examined composts, the moisture was at the level of around 34% (Table 2), which proved sufficient for commercialization.
The ss-effluents were characterized by around 28% of the organic carbon (OC) content, while the ms-effluents reached almost 19% (Table 3). Stürmer et al. (2020) showed a 41.6% average OC content [18], while Möller et al. (2012) reported a carbon content of 28–47% in the literature research [25]. Furthermore, it was stated that an OC share of 80–95% of AD feedstock resulted in a 22.4–44.6% OC content in the digestate. Based on that, it can be assumed that, in OFMSW, the organic carbon share was much lower and might be affected by the mineral fractions content.
The balance between carbon and nitrogen and phosphorus and potassium is essential to state the agronomic use of an organic product [26]; therefore, their contents are under requirements. For instance, the total nitrogen (TN), phosphorus (P), and potassium (K) contents are under French regulations of 3% of the fresh matter [23]. According to the German requirements, fertilizers must have at least 0.5%, 0.3%, and 0.5% DM of TN, P, and K, respectively [23]. The Polish requirements are minimal at 0.3%, 0.2%, and 0.3%, respectively (Table 2 and Table 3). The EU Regulations [19] established a minimal content of their sums at 1% for compound fertilizers. The ms-compost did not fulfill even the Polish requirements (Table 2). The ss-compost achieved national expectations. However, the EU regulations were met only regarding TN (1.06% of the DM), yet the total content of the TN, P, and K was only 2.48% of the DM (Table 2). In the case of ms-effluents, the TN content was at the level of 2.7% of DM, which met even the EU requirements for single-component fertilizers (2%). The ss-effluents contained double TN loads (5.74%) (Table 3). The EU Regulations [19] also foresee limits for copper and zinc as micronutrients (Table 3). Their concentrations in soil might be crucial if they are nutrients or toxic. Excess copper undermines plant growth [27]. The zinc limit was exceeded in the ms-effluents by over 65% (Table 2).
The heavy metals contents in fertilizers must be maintained on a low level that guarantees the safe production of food and animal feed in cultivated crops [28]. Due to OFMSW heterogeneous characteristics, it is difficult to generalize heavy metal contaminations [18]. The AD and post-composting processes ensure homogeneity of the materials. Furthermore, heavy metal availability and solubility decrease due to the precipitation processes [25]. Nevertheless, the amount of metal remains constant compared to the input [18]. Since the heavy metal loads affect environmental contamination, value limits are set. The ss-compost fulfills the national and EU requirements (Table 2), while in the ms-compost, the contents of chrome (175 mg/kg), nickel (60.4 mg/kg), and lead (221 mg/kg) were higher than the limits (Table 2). The ss-compost contamination of heavy metals was similar to the Italian composts examined by Beggio et al. [17] and Austrian [18]. Regarding ms-effluents, the acceptable amount of nickel (63.7 mg/kg) was exceeded, while the lead content (138 g/kg) was at the threshold limit values (Table 3).
The discrepancies in limits can be noticed in the local requirements (Table 2 and Table 3). As for liquid biofertilizers, the Swedish Cd maximum contamination was established at 1, while the Greek at 3 and Czech at 2-mg/kg dry matter. In contrast, the Cu content was at the maximum levels of 600, 400, and 159-mg/kg dry matter, respectively (Table 3). Additionally, in composts, the heavy metal limits in various standards from across Europe can be found, e.g., the Greek Cr maximum contamination was established at 250, while the Czech at 100 and the Dutch at 50-mg/kg dry matter (Table 2). However, compared to the local requirements, the European ones are on a higher level (Table 2 and Table 3). Thus, it can be stated that they indicate target values that the EU Members should strive to achieve. The reason for the difficulty of meeting them might be the source segregation quality. The heavy metal contents might also affect the coal ashes contents or the waste origin from the urban area.
Another critical issue is the hygienic parameters. Every soil amendment cannot contain pathogens, toxins that threaten the safety of crops, animals, and humans; thus, legal requirements are implemented. Due to fertilizers containing animal byproducts, including food waste, Regulation (EU) 142/2011 necessitates the absence of Salmonella in 25 g of a sample and the number of colony-forming units (CFU) less than 1000 of Enterobacteriaceae or Enterococci. These requirements were applied in the EU regulation of fertilizers. The AD in thermophilic conditions ensures the proper sanitization of OFMSW [14].
It is important to produce good-quality organic fertilizers, because, in the long term, the usage of inorganic fertilizers causes water pollution and soil structure degradation [29,30]. In contrast, organic fertilizers might improve them [31]. Cavagnaro [32] confirmed the improvement in the effectiveness of essential nutrients for improving plant growth. Thus, it can be stated that waste biological treatment can bring environmental gains. AD brings more benefits than single composting, mainly due to the possibility of energy recovery from waste [33], despite the digestate and its proper sanitization [14]. Some researchers have confirmed the soil amendment effect of a digestate [17,34]. Contrariwise, some researchers reported negative impacts of applying a digestate. The soil toxicity might appear due to uneven distribution, uncontrolled nitrogen application, or inadequate quality assessment, including sanitization [35,36]. Thus, the production of good-quality fertilizers requires the careful control of all aspects of the process, from feedstock to field. Considering the potential negative effects of using a digestate from agricultural waste, providing a safety assurance for the digestate is essential in the organic fraction of municipal waste. Hence, the thermophilic aerobic digestate treatment should ensure the sanitization of OFMSW [14], and as a second step, the aerobic digestate treatment should provide higher-quality compost.

4. Conclusions

Based on the compost examination, ss-compost fulfills the local fertilizers’ requirements, while the ms-compost metal contents are too high. The nitrogen and phosphorus contents are even two times higher in ss-compost than in ms-compost, while the potassium concentration is even three times higher. Regarding the metals, the biggest exceeding limit values were noted for lead (over 80 mg/kg) and chrome (75 mg/kg). The heavy metal contamination of the ms-compost was much higher and followed by a lower concentration of nutrients.
Based on the effluents examination, ss-effluents fulfilled the fertilizers’ requirements, while, regarding ms-effluents, the limit values were exceeded. The nitrogen content was even two times higher in ss-effluents than in ms-effluents. Regarding metals, the biggest exceeding limit values were noted for nickel (over 3 mg/kg) and zinc (over 500 mg/kg). In general, the heavy metal contamination of ms-effluents was much higher. Therefore, the European requirements should be the goal for European countries to produce high-quality and safe biofertilizers.
One of the more significant findings of this study was that compost and effluents derived from separately collected biowaste AD are appropriate for biofertilizer generation and usage, while the OFMSW suitability is limited. However, to meet the EU requirements, the source segregation quality should be improved and environmental pollution reduced.

Author Contributions

P.S. and M.K. conceived and designed the experiments, P.S. performed the experiments, P.S. analyzed the data, P.S. contributed the reagents/materials/analysis tools, and P.S. and M.K. wrote and revised the paper. All authors have read and agreed to the published version of the manuscript.

Funding

The project is financed by the Ministry of Science and Higher Education in Poland under the programme “Regional Initiative of Excellence” 2019–2022, project number 015/RID/2018/19, total funding amount: 10 721 040.00 PLN.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Not applicable.

Acknowledgments

This research was supported by Zakład Gospodarki Odpadami GAĆ in Poland.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Aghbashlo, M.; Tabatabaei, M.; Soltanian, S.; Ghanavati, H. Biopower and biofertilizer production from organic municipal solid waste: An exergoenvironmental analysis. Renew. Energy 2019, 143, 64–76. [Google Scholar] [CrossRef]
  2. Jakubus, M. A Comparative Study of Composts Prepared from Various Organic Wastes Based on Biological and Chemical Parameters. Agronomy 2020, 10, 869. [Google Scholar] [CrossRef]
  3. Abad, V.; Avila, R.; Vicent, T.; Font, X. Promoting circular economy in the surroundings of an organic fraction of municipal solid waste anaerobic digestion treatment plant: Biogas production impact and economic factors. Bioresour. Technol. 2019, 283, 10–17. [Google Scholar] [CrossRef] [PubMed]
  4. Kaza, S.; Yao, L.; Bhada-Tata, P.; Van Woerden, F. What a Waste 2.0: A Global Snapshot of Solid Waste Management to Subscriber-only Content; World Bank Publications: Washington, DC, USA, 2018; ISBN 9781464813290. [Google Scholar]
  5. Lim, L.S.; Lee, L.H.; Wu, T.Y. Sustainability of using composting and vermicomposting technologies for organic solid waste biotransformation: Recent overview, greenhouse gases emissions and economic analysis. J. Clean. Prod. 2016, 111, 262–278. [Google Scholar] [CrossRef]
  6. Seruga, P.; Krzywonos, M.; Wilk, M. Thermophilic co-digestion of the organic fraction of municipal solid wastes—the influence of food industry wastes addition on biogas production in full-scale operation. Molecules 2018, 23, 3146. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  7. Alam, O.; Qiao, X. An in-depth review on municipal solid waste management, treatment and disposal in Bangladesh. Sustain. Cities Soc. 2019, 52, 101775. [Google Scholar] [CrossRef]
  8. Pawlak-Kruczek, H.; Niedzwiecki, L.; Sieradzka, M.; Mlonka-Mędrala, A.; Baranowski, M.; Serafin-Tkaczuk, M.; Magdziarz, A. Hydrothermal carbonization of agricultural and municipal solid waste digestates—Structure and energetic properties of the solid products. Fuel 2020, 275, 117837. [Google Scholar] [CrossRef]
  9. Panigrahi, S.; Dubey, B.K. A critical review on operating parameters and strategies to improve the biogas yield from anaerobic digestion of organic fraction of municipal solid waste. Renew. Energy 2019, 143, 779–797. [Google Scholar] [CrossRef]
  10. Khoshnevisan, B.; Tsapekos, P.; Alvarado-Morales, M.; Angelidaki, I. Process performance and modelling of anaerobic digestion using source-sorted organic household waste. Bioresour. Technol. 2018, 247, 486–495. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  11. EBA Statistical Report 2018. Available online: https://www.europeanbiogas.eu/wp-content/uploads/2019/05/EBA_Statistical-Report-2018_AbrigedPublic_web.pdf (accessed on 26 September 2020).
  12. Seruga, P.; Krzywonos, M.; Wilk, M. Treatment of By-Products Generated from Anaerobic Digestion of Municipal Solid Waste. Waste Biomass Valorization 2019, 11, 4933–4940. [Google Scholar] [CrossRef] [Green Version]
  13. Seruga, P.; Krzywonos, M.; Seruga, A.; Niedźwiecki, Ł.; Pawlak-Kruczek, H.; Urbanowska, A. Anaerobic Digestion Performance: Separate Collected vs. Mechanical Segregated Organic Fractions of Municipal Solid Waste as Feedstock. Energies 2020, 13, 3768. [Google Scholar] [CrossRef]
  14. Seruga, P.; Krzywonos, M.; Paluszak, Z.; Urbanowska, A.; Pawlak-Kruczek, H.; Niedzwiecki, L.; Pińkowska, H. Pathogen Reduction Potential in Anaerobic Digestion. Molecules 2020, 25, 275. [Google Scholar] [CrossRef] [Green Version]
  15. Fuldauer, L.I.; Parker, B.M.; Yaman, R.; Borrion, A. Managing anaerobic digestate from food waste in the urban environment: Evaluating the feasibility from an interdisciplinary perspective. J. Clean. Prod. 2018, 185, 929–940. [Google Scholar] [CrossRef]
  16. Cesaro, A.; Belgiorno, V.; Guida, M. Compost from organic solid waste: Quality assessment and European regulations for its sustainable use. Resour. Conserv. Recycl. 2015, 94, 72–79. [Google Scholar] [CrossRef]
  17. Beggio, G.; Schievano, A.; Bonato, T.; Hennebert, P.; Pivato, A. Statistical analysis for the quality assessment of digestates from separately collected organic fraction of municipal solid waste (OFMSW) and agro-industrial feedstock. Should input feedstock to anaerobic digestion determine the legal status of digestate? Waste Manag. 2019, 87, 546–558. [Google Scholar] [CrossRef]
  18. Stürmer, B.; Pfundtner, E.; Kirchmeyr, F.; Uschnig, S. Legal requirements for digestate as fertilizer in Austria and the European Union compared to actual technical parameters. J. Environ. Manag. 2020, 253, 109756. [Google Scholar] [CrossRef]
  19. The European Parliament and the Council of the European Union Regulation (EU) 2019/1009 of the European Parliament and of the Council of 5 June 2019 laying down rules on the making available on the market of EU fertilising products and amending Regulation (EC) No 1069/2009 and (EC) No 1107/2009 and repealing Regulat. Off. J. Eur. Union 2019, 2019, 1–114.
  20. Ostrowska, A.; Gawliński, S.; Szczubialka, Z. Methods for Analysis and Evaluation of Soil and Plant Properties, 1st ed.; IOŚ Warszawa: Warszawa, Poland, 1991; pp. 158–167. (In Polish) [Google Scholar]
  21. Polish Regulation: Minister of Agriculture and Rural Development Regulation of 18 June 2008 on the implementation of certain provisions of fertilizers and fertilization. J. Law 2008, 119. Available online: http://isap.sejm.gov.pl/isap.nsf/DocDetails.xsp?id=wdu20081190765 (accessed on 25 September 2020). (In Polish).
  22. Foster, P.; Prasad, M. Development of Quality Standards for Compost and Digestate in Ireland; Environmental Protection Agency: Wexford, Ireland, 2021. [Google Scholar]
  23. Teglia, C.; Tremier, A.; Martel, J.L. Characterization of solid digestates: Part 2, assessment of the quality and suitability for composting of six digested products. Waste Biomass Valorization 2011, 2, 113–126. [Google Scholar] [CrossRef]
  24. Guilayn, F.; Jimenez, J.; Martel, J.L.; Rouez, M.; Crest, M.; Patureau, D. First fertilizing-value typology of digestates: A decision-making tool for regulation. Waste Manag. 2019, 86, 67–79. [Google Scholar] [CrossRef]
  25. Möller, K.; Müller, T. Effects of anaerobic digestion on digestate nutrient availability and crop growth: A review. Eng. Life Sci. 2012, 12, 242–257. [Google Scholar] [CrossRef]
  26. Teglia, C.; Tremier, A.; Martel, J.L. Characterization of solid digestates: Part 1, review of existing indicators to assess solid digestates agricultural use. Waste Biomass Valorization 2011, 2, 43–58. [Google Scholar] [CrossRef]
  27. Yruela, I. Copper in plants. Braz. J. Plant Physiol. 2005, 17, 145–156. [Google Scholar] [CrossRef] [Green Version]
  28. Insam, H.; Gómez-Brandón, M.; Ascher, J. Manure-based biogas fermentation residues—Friend or foe of soil fertility? Soil Biol. Biochem. 2015, 84, 1–14. [Google Scholar] [CrossRef]
  29. Fuentes, M.; Govaerts, B.; De Leon, F.; Hidalgo, C.; Dendooven, L.; Sayre, K.D.; Etchevers, J. Fourteen years of applying zero and conventional tillage, crop rotation and residue management systems and its effect on physical and chemical soil quality. Eur. J. Agron. 2009, 30, 228–237. [Google Scholar] [CrossRef]
  30. Yu, H.; Ling, N.; Wang, T.; Zhu, C.; Wang, Y.; Wang, S.; Gao, Q. Responses of soil biological traits and bacterial communities to nitrogen fertilization mediate maize yields across three soil types. Soil Tillage Res. 2019, 185, 61–69. [Google Scholar] [CrossRef]
  31. Wang, M.C.; Yang, C.H. Type of fertilizer applied to a paddy-upland rotation affects selected soil quality attributes. Geoderma 2003, 114, 93–108. [Google Scholar] [CrossRef]
  32. Cavagnaro, T.R. Impacts of compost application on the formation and functioning of arbuscular mycorrhizas. Soil Biol. Biochem. 2014, 78, 38–44. [Google Scholar] [CrossRef] [Green Version]
  33. Heidari, R.; Yazdanparast, R.; Jabbarzadeh, A. Sustainable design of a municipal solid waste management system considering waste separators: A real-world application. Sustain. Cities Soc. 2019, 47, 101457. [Google Scholar] [CrossRef]
  34. Tambone, F.; Orzi, V.; D’Imporzano, G.; Adani, F. Solid and liquid fractionation of digestate: Mass balance, chemical characterization, and agronomic and environmental value. Bioresour. Technol. 2017, 243, 1251–1256. [Google Scholar] [CrossRef] [PubMed]
  35. Lukehurst, C.T.; Frost, P.; Al Seadi, T. Utilisation of digestate from biogas plants as biofertiliser. IEA Bioenergy 2010. Available online: https://www.iea-biogas.net/files/daten-redaktion/download/publi-task37/Digestate_Brochure_Revised_12-2010.pdf (accessed on 26 September 2020).
  36. Tigini, V.; Franchino, M.; Bona, F.; Varese, G.C. Is digestate safe? A study on its ecotoxicity and environmental risk on a pig manure. Sci. Total Environ. 2016, 551–552, 127–132. [Google Scholar] [CrossRef]
Energies 14 03971 g001 550
Figure 1. Simplified diagram of the biological treatment facility.
Figure 1. Simplified diagram of the biological treatment facility.
Energies 14 03971 g001
Table
Table 1. The composition of the mechanically sorted organic fraction of municipal solid waste (OFMSW) and separately collected biowaste.
Table 1. The composition of the mechanically sorted organic fraction of municipal solid waste (OFMSW) and separately collected biowaste.
FractionOFMSWBiowaste
Mass ShareMass Share
Organic (incl. green waste) (%)46.3 ± 2.367.2 ± 6.1
Wood (%)6.2 ± 0.77.4 ± 0.8
Paper (%)3.1 ± 0.32.9 ± 0.5
Plastics (%)3.3 ± 0.51.2 ± 0.3
Glass (%)4.6 ± 0.91.0 ± 0.3
Inert waste (%)3.9 ± 1.01.5 ± 0.6
Textiles (%)0.2 ± 0.10.1 ± 0.1
Metals (%)0.1 ± 0.10.1 ± 0.1
Hazardous (%)0.1 ± 0.10.1 ± 0.1
Tetra Pak (%)0.5 ± 0.10.3 ± 0.1
Others (%)0.9 ± 0.20.5 ± 0.1
Fine fraction 0–15 mm (%)30.8 ± 3.917.7 ± 2.7
Table
Table 2. Characterization of the composts from digestate derived from the organic fraction of the municipal solid waste (ms-compost) and source-segregated biowaste (ss-compost).
Table 2. Characterization of the composts from digestate derived from the organic fraction of the municipal solid waste (ms-compost) and source-segregated biowaste (ss-compost).
Parameterms-Compostss-CompostPolish Required Levels [21]EU Required Levels [19]German Required Levels [22]Czech Required Levels [22]Dutch Required Levels [22]Greek Required Levels [22]
Metal contents
Cadmium (Cd) (mg/kg dry matter)<1.0<1.0Max. 5Max. 1.5Max. 1.5Max. 2Max. 1Max. 3
Chrome (Cr) (mg/kg dry matter)175 ± 6.623.5 ± 0.01Max. 100Max. 100 *Max. 100Max. 100Max. 50Max. 250
Mercury (Hg) (mg/kg dry matter)<0.3<0.3Max. 2Max. 1Max. 1Max. 1Max. 0.3Max. 2.5
Nickel (Ni) (mg/kg dry matter)60.4 ± 2.118.1 ± 0.8Max. 60Max. 50Max. 50Max. 50Max. 20Max. 100
Lead (Pb) (mg/kg dry matter)221 ± 10.1111 ± 10.1Max. 140Max. 120Max. 150Max. 100Max. 100Max. 300
Non-metal contents
Organic matter (% dry matter)28.2 ± 4.031.6 ± 3.9Min. 30
Phosphorus (P2O5) (% dry matter)0.21 ± 0.20.48 ± 0.2Min. 0.2Min.1.0 **
Potassium (K2O) (% dry matter)0.31 ± 0.060.94 ± 0.06Min. 0.5Min. 1.0 **
Total nitrogen (% dry matter)0.6 ± 0.11.06 ± 0.1Min. 0.3Min.1.0 **
pH value (-)7.8 ± 0.17.8 ± 0.1-
Water content (%)33.5 ± 4.834.5 ± 6.0-
* Hexavalent chromium (Cr VI) must not exceed 2-mg/kg dry matter. ** The sum of each must be at least 3% for compound fertilizer.
Table
Table 3. The effluents’ characterization from the anaerobic digestion of the organic fraction of municipal solid waste (ms-effluents) and source-segregated biowaste (ss-effluents).
Table 3. The effluents’ characterization from the anaerobic digestion of the organic fraction of municipal solid waste (ms-effluents) and source-segregated biowaste (ss-effluents).
Parameterms-Effluentsss-EffluentsPolish Required Levels [21]EU Required Levels [19]German Required Levels [22]Czech Required Levels [22]Swedish Required Levels [22]Greek Required Levels [22]
Metal contents
Cadmium (Cd) (mg/kg dry matter)2.02 ± 0.410.73 ± 0.15Max. 5Max. 1.5Max. 2Max. 2Max. 1Max. 3
Chrome (Cr) (mg/kg dry matter)84.6 ± 21.220.9 ± 5.3Max. 100Max. 100 *Max. 100Max. 100Max. 100Max. 250
Cooper (Cu) (mg/kg dry matter)251 ± 5159.4 ± 11.9-Max. 300Max. 100Max. 150Max. 600Max. 400
Lead (Pb) (mg/kg dry matter)138 ± 2844.4 ± 8.9Max. 140Max. 120Max. 150Max. 100Max. 100Max. 300
Mercury (Hg) (mg/kg dry matter)1.0 ± 0.30.26 ± 0.08Max. 2Max. 1Max. 1Max. 1Max. 1Max. 3
Nickel (Ni) (mg/kg dry matter)63.7 ± 12.818.1 ± 3.7Max. 60Max. 50Max. 50Max. 50Max. 50Max. 100
Zinc (Zn) (mg/kg dry matter)1328 ± 332449 ± 113-Max. 800Max. 400Max. 600Max. 800Max. 1200
Nonmetal contents
Organic matter (% dry matter)34.0 ± 8.543.4 ± 10.9Min. 30-
Phosphorus (P2O5) (% dry matter)0.77 ± 0.070.64 ± 0.06Min. 0.2Min. 1
Total organic carbon (TOC) (% dry matter)18.7 ± 5.728.3 ± 8.5-Min. 5
Total nitrogen (% dry matter)2.73 ± 0.415.74 ± 0.86Min. 0.3Min. 1
Dry matter (%)21.6 ± 4.413.6 ± 2.8--
* Hexavalent chromium (Cr VI) must not exceed 2-mg/kg dry matter.
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Share and Cite

MDPI and ACS Style

Seruga, P.; Krzywonos, M. Separate Collected Versus Mechanical Segregated Organic Fractions in Terms of Fertilizers Suitability. Energies 2021, 14, 3971. https://doi.org/10.3390/en14133971

AMA Style

Seruga P, Krzywonos M. Separate Collected Versus Mechanical Segregated Organic Fractions in Terms of Fertilizers Suitability. Energies. 2021; 14(13):3971. https://doi.org/10.3390/en14133971

Chicago/Turabian Style

Seruga, Przemysław, and Małgorzata Krzywonos. 2021. "Separate Collected Versus Mechanical Segregated Organic Fractions in Terms of Fertilizers Suitability" Energies 14, no. 13: 3971. https://doi.org/10.3390/en14133971

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop