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14 pages, 3115 KiB

Open AccessArticle

Anaerobic Degradability of Commercially Available Bio-Based and Oxo-Degradable Packaging Materials in the Context of their End of Life in the Waste Management Strategy

by Magdalena Zaborowska, Katarzyna Bernat, Bartosz Pszczółkowski, Irena Wojnowska-Baryła and Dorota Kulikowska

Sustainability 2021, 13(12), 6818; https://doi.org/10.3390/su13126818 - 16 Jun 2021

Cited by 15 | Viewed by 2582

Abstract

There are discrepancies concerning the time frame for biodegradation of different commercially available foils labeled as biodegradable; thus, it is essential to provide information about their biodegradability in the context of their end of life in waste management. Therefore, one-year mesophilic (37 °C) [...] Read more.

There are discrepancies concerning the time frame for biodegradation of different commercially available foils labeled as biodegradable; thus, it is essential to provide information about their biodegradability in the context of their end of life in waste management. Therefore, one-year mesophilic (37 °C) anaerobic degradation tests of two bio-based foils (based on starch (F_S), polylactic acid (F_PLA)) and oxo-degradable material (F_OXO) were conducted in an OxiTop system. Biodegradation was investigated by measuring biogas production (BP) and analyzing structural changes with differential scanning calorimetry, polarizing and digital microscopic analyses, and Fourier transform infrared spectroscopy. After 1 year, F_OXO had not degraded; thus, there were no visible changes on its surface and no BP. The bio-based materials produced small amounts of biogas (25.2, F_PLA, and 30.4 L/kg VS, F_S), constituting 2.1–2.5% of theoretical methane potential. The foil pieces were still visible and only starting to show damage; some pores had appeared in their structure. The structure of F_PLA became more heterogeneous due to water diffusing into the structure. In contrast, the structure of F_S became more homogenous although individual cracks and fissures appeared. The color of F_S had changed, indicating that it was beginning to biodegrade. The fact that F_S and F_PLA showed only minor structural damage after a one-year mesophilic degradation indicates that, in these conditions, these materials would persist for an unknown but long amount of time. Full article

(This article belongs to the Special Issue Wastewater Treatment and Solid Waste Management)

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11 pages, 668 KiB

Open AccessArticle

Waste Willow-Bark from Salicylate Extraction Successfully Reused as an Amendment for Sewage Sludge Composting

by Dorota Kulikowska and Katarzyna Bernat

Sustainability 2021, 13(12), 6771; https://doi.org/10.3390/su13126771 - 15 Jun 2021

Cited by 11 | Viewed by 1826

Abstract

Due to the fact that compost is a valuable fertilizer that serves principally as a source of macronutrients, composting is one of the preferred methods of management of organic waste, including municipal sewage sludge. However, due to its high moisture content and low [...] Read more.

Due to the fact that compost is a valuable fertilizer that serves principally as a source of macronutrients, composting is one of the preferred methods of management of organic waste, including municipal sewage sludge. However, due to its high moisture content and low C/N ratio, sewage sludge cannot be composted alone. This study investigated the usefulness of waste willow-bark (WWB) (after salicylate extraction) as an amendment for municipal sewage-sludge composting in a two-stage system: an aerated bioreactor and a periodically turned windrow. Both organic matter (OM) removal and humification progress were monitored. It was found that the prepared feedstock (70% sewage sludge, 25% WWB, and 5% wood chips, w/w) enabled proper temperature profiles to be obtained, with a maximum temperature of 72.3 °C. The rate constant of OM degradation in the bioreactor was 0.25 d⁻¹, almost 4-fold higher than that in the windrows. During composting, the concentrations of humic substances (HS), humic acids (HA), and the fulvic fraction (FF) changed. HS, HA, and FF formation proceeded according to 1. order kinetics, and their respective rates were 1.33 mg C/(g OM d), 1.03 mg C/(g OM d), and 0.76 mg C/(g OM d). However, in mature compost, FF predominated (ca. 70%) in HS. These results indicate that waste willow-bark, a product of salicylate extraction, can be successfully reused as an amendment during municipal sewage sludge composting. Both waste willow-bark reuse and sewage sludge composting are compatible with a circular economy. Full article

(This article belongs to the Special Issue Wastewater Treatment and Solid Waste Management)

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12 pages, 1521 KiB

Open AccessArticle

Post-Treatment of the Effluent from Anaerobic Digestion of the Leachate in Two-Stage SBR System Using Alternative Carbon Sources

by Katarzyna Bernat, Dorota Kulikowska, Magdalena Zielińska, Magdalena Zaborowska, Irena Wojnowska-Baryła and Magdalena Łapińska

Sustainability 2021, 13(11), 6297; https://doi.org/10.3390/su13116297 - 02 Jun 2021

Cited by 5 | Viewed by 2106

Abstract

Although anaerobic digestion (AD) enables biogas production and facilitates renewable electricity production, its effluent must be post-treated before discarding it into the environment. However, during AD designing, the post-treatment step is often overlooked. This paper presents the kinetics and efficiency of nitrogen removal [...] Read more.

Although anaerobic digestion (AD) enables biogas production and facilitates renewable electricity production, its effluent must be post-treated before discarding it into the environment. However, during AD designing, the post-treatment step is often overlooked. This paper presents the kinetics and efficiency of nitrogen removal from effluent after AD of leachate from the aerobic stabilization of the organic fraction of municipal solid waste. A two-stage SBR system was used. An ammonium oxidation rate of 15.5 mg N-NH₄/(L·h) ensured a 98% nitrification efficiency (I stage). For denitrification (II stage), alternative carbon sources (ACS) (molasses, crude glycerine, or distillery stillage) were used. Two volumetric exchange rates (n) were tested: 0.35 1/d (COD/N-NO₃ ratio of 8) and 0.5 1/d (COD/N-NO₃ of 7). With all ACS and COD/N-NO₃ ratios, almost 100% of nitrate was denitrified; at the COD/N-NO₃ of 8, biodegradable organics remained in the effluents. At the COD/N-NO₃ of 7, the denitrification removal rates were lower (29.6-45.1 mg N-NO_x/(L·h)) than at the ratio of 8 (72.1–159.5 mg N-NO_x/(L·h)), because of temporal nitrite accumulation. The highest nitrate removal rates were obtained with molasses, the lowest with a distillery stillage. Considering the nitrate removal rate and the effluent COD concentration, molasses was recommended as the most effective carbon source for AD effluent treatment at the COD/N-NO₃ of 7. Full article

(This article belongs to the Special Issue Wastewater Treatment and Solid Waste Management)

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16 pages, 3559 KiB

Open AccessArticle

Insight into the Composition of the Stabilized Residual from a Full-Scale Mechanical-Biological Treatment (MBT) Plant in Terms of the Potential Recycling and Recovery of Its Contaminants

by Katarzyna Bernat, Irena Wojnowska-Baryła, Magdalena Zaborowska and Izabela Samul

Sustainability 2021, 13(10), 5432; https://doi.org/10.3390/su13105432 - 12 May 2021

Cited by 10 | Viewed by 1598

Abstract

There is a lack of knowledge about the composition and particle size distribution of the <80 mm fraction mechanically separated from residual municipal solid waste (rMSW) and the stabilized residual (SR) after aerobic stabilization in a full-scale MBT plant. Therefore, the composition of [...] Read more.

There is a lack of knowledge about the composition and particle size distribution of the <80 mm fraction mechanically separated from residual municipal solid waste (rMSW) and the stabilized residual (SR) after aerobic stabilization in a full-scale MBT plant. Therefore, the composition of the particle size fractions (>60 mm, 60–40 mm, 40–10 mm) of the <80 mm fraction and SR, collected in all seasons (summer (S), autumn (A), winter (W), spring (Sp)), was determined. Biodegradable waste (vegetable waste, other organic waste, paper, cardboard) constituted from 44.1% (A) to 54.3% (Sp) of the <80 mm fraction and it decreased to 8.5% (W) to 17.1% (S) in the SR, after effective biodegradation. In SR, the smaller particle size fractions (up to 40 mm) predominated. The main contaminants in SR were plastic, glass, metal, and other waste. Hierarchical clustering indicated that the composition of the particle size fractions of SR was more similar across four seasons than that of the <80 mm fraction. After stabilization and separation, the share of contaminants increased in the SR size fractions, which means that their recovery before landfilling may be profitable. This suggests a new direction in waste management that would be consistent with the principles of a circular economy, in which a waste product, like SR, which previously could only be landfilled, becomes a source of secondary materials. Full article

(This article belongs to the Special Issue Wastewater Treatment and Solid Waste Management)

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12 pages, 2440 KiB

Open AccessArticle

Fouling Identification for Nanofiltration Membrane and the Potential Reduction of Pollutants in the Leachate by Using Fe/Al/PAC Coagulation

by Chang-wei He, Hui Wang, Luo-chun Wang, Zi-yang Lou, Li Bai, Hai-feng Zong and Zhen Zhou

Sustainability 2021, 13(3), 1114; https://doi.org/10.3390/su13031114 - 21 Jan 2021

Cited by 2 | Viewed by 1635

Abstract

The reduction in the fouling is an important way to maintain the steady operation for the nanofiltration (NF) process in leachate treatment. The fouling components from the real leachate treatment process were identified using a scanning electron microscope equipped with X-ray microanalysis (SEM-EDS), [...] Read more.

The reduction in the fouling is an important way to maintain the steady operation for the nanofiltration (NF) process in leachate treatment. The fouling components from the real leachate treatment process were identified using a scanning electron microscope equipped with X-ray microanalysis (SEM-EDS), infrared spectroscopy (FTIR), atomic analysis and three-dimensional fluorescence (EEM) analysis, and the coagulation of Fe/Al/PAC was selected to reduce the potential pollutants in the leachate, to reduce the potential fouling. It was found that organic humic acid and calcium-magnesium precipitates were the main pollutants in NF fouling. The foulant layer was the result of the combination of organic matter, inorganic precipitation, colloids and microorganisms, and the colloids precipitation is more important, and should be removed in advance. PAC was found to be more efficiency to reduce the colloids and the inorganic matter, among the coagulants selection, with the chemical oxygen demand (COD) removal rate of 55.1%. The commercially available coagulant-poly aluminum chloride (PAC) was chosen as a coagulant. The removal rate of leachate reached 55.1%, and the flow rate through the membrane was increased by 35.8% under the optimum condition (pH was 5.0, PAC dosage was 100 mg/L, and the membrane pressure was 0.4 MPa). Through the pilot scale test, the effluent was connected to the microfiltration membrane and then to the nanofiltration membrane and the practical engineering application is feasible. Full article

(This article belongs to the Special Issue Wastewater Treatment and Solid Waste Management)

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12 pages, 2287 KiB

Open AccessArticle

The Influence of Sedimentation Ponds of the Former Soda “Solvay” Plant in Krakow on the Chemistry of the Wilga River

by Justyna Likus-Cieślik and Marcin Pietrzykowski

Sustainability 2021, 13(2), 993; https://doi.org/10.3390/su13020993 - 19 Jan 2021

Cited by 1 | Viewed by 1775

Abstract

This paper explores how the chemistry of the Wilga River is affected by the sedimentation ponds at the former Soda “Solvay” Plant in Krakow. Despite the revitalization of the sedimentation ponds about 30 years ago, the chemistry of the samples was characterized by [...] Read more.

This paper explores how the chemistry of the Wilga River is affected by the sedimentation ponds at the former Soda “Solvay” Plant in Krakow. Despite the revitalization of the sedimentation ponds about 30 years ago, the chemistry of the samples was characterized by high EC (from 845 to 3000 µS cm⁻¹), high concentration of Cl⁻ (up to 800 mg L⁻¹), Ca (up to 270 mg L⁻¹), and SO₄²⁻ (up to 115 mg L⁻¹), and a high value for Na (up to 270 mg L⁻¹) was noted—surface water quality standards were exceeded. The effect of high mineralization by those elements, generated in wastewater during soda waste production, were noted to have seasonal and vertical variability. We concluded that, despite the industrial shutdown and revitalization processes, the drainage of industrial water can have serious and long-term negative effects on quality of water and the Wilga River ecosystem. The Wilga River is one of the most important examples of important environmental problems in urban areas. Full article

(This article belongs to the Special Issue Wastewater Treatment and Solid Waste Management)

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13 pages, 2265 KiB

Open AccessArticle

Loading Capacity of Sewage Sludge for Forestry Application in Chinese Provincial Capital Cities

by Xiaoxia Zhang, Tonggang Zha, Jiangang Zhu, Xiaoping Guo and Yi Liu

Sustainability 2020, 12(18), 7551; https://doi.org/10.3390/su12187551 - 14 Sep 2020

Cited by 2 | Viewed by 1996

Abstract

The application of sewage sludge (SS) in forestry is considered a viable option. However, the long-term application of SS potentially leads to metal accumulation, posing an environmental risk. Understanding the loading capacity of SS for forestry application is therefore of great significance. We [...] Read more.

The application of sewage sludge (SS) in forestry is considered a viable option. However, the long-term application of SS potentially leads to metal accumulation, posing an environmental risk. Understanding the loading capacity of SS for forestry application is therefore of great significance. We used data from published studies and statistical bulletins across 31 provincial capital cities (PCCs) in China to calculate the loading capacity (LC) of SS for forestry application for each PCC. The results are as follows: (1) the mean value of the priority control threshold was 33 t·ha⁻¹·y⁻¹ in 31 PCCs, while the variations ranged from 7 to 91 t·ha⁻¹·y⁻¹ among different PCCs. The priority control thresholds (S_mins) of 1/2 PCCs were higher than 30 t·ha⁻¹·y⁻¹ (CJ-T 362-2011). The S_min values of Lanzhou, Tianjin, Hohhot, Shanghai, and Yinchuan were above 55 t·ha⁻¹·y⁻¹, but S_min values of Kunming and Changsha were below 10 t·ha⁻¹·y⁻¹. (2) Cd was the priority control metal in most of the PCCs (27/31), with the exception of Shanghai and Guangzhou (Cu), Beijing (Hg), and Tianjin (Zn). (3) The total loading capacity was 507 million t·y⁻¹, which was 125 times higher than the total quantity of the dry SS (404 × 10⁴ t) for the 31 PCCs. Our results have important practical significance for the use of urban sludge forest land in China and suggest that SS disposal policies need to be tailored to specific regions. We provide a scientific basis to guide the development of national and provincial forestry policies. Full article

(This article belongs to the Special Issue Wastewater Treatment and Solid Waste Management)

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16 pages, 2758 KiB

Open AccessArticle

Transport Models of Ammonium Nitrogen in Wastewater from Rare Earth Smelteries by Reverse Osmosis Membranes

by Shuanglin Gui, Zhaohuan Mai, Jiaqi Fu, Yuansong Wei and Jinbao Wan

Sustainability 2020, 12(15), 6230; https://doi.org/10.3390/su12156230 - 03 Aug 2020

Cited by 12 | Viewed by 2064

Abstract

Wastewater from rare earth smelteries contains large amounts of ammonium nitrogen (NH₄⁺-N), which causes severe environmental problems. In this contribution, the desalination efficiency of reverse osmosis (RO) was investigated in the treatment of NH₄Cl or NaCl solutions from [...] Read more.

Wastewater from rare earth smelteries contains large amounts of ammonium nitrogen (NH₄⁺-N), which causes severe environmental problems. In this contribution, the desalination efficiency of reverse osmosis (RO) was investigated in the treatment of NH₄Cl or NaCl solutions from 0.1 to 40 g/L under different operating pressures with a commercial RO membrane. Experimental results showed that when an operating pressure above 30 bar is applied to the 5 g/L NH₄Cl solution, the permeate was found to meet the discharge standards of NH₄⁺-N. Compared to NH₄Cl, the permeate fluxes of NaCl solutions were higher due to the higher net driving force and lower propensity to membrane fouling. Theoretical models indicate a linear relationship between water flux and the net driving force for both NH₄Cl and NaCl solutions. On the contrary, a power function between the salt flux and concentration difference correlated well with the experimental data for salt transport. The equations for water and salt transport obtained by this work would provide a facile and practical means for predicting the membrane performance in design and optimization of RO processes for the treatment of wastewater from the rare earth industry. Full article

(This article belongs to the Special Issue Wastewater Treatment and Solid Waste Management)

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