Search

Deinking paper sludge (DPS) soil amendments have potential as a climate change mitigation strategy. Understanding how DPS application affects carbon mineralization in different soil textures is crucial but has not been well investigated. We performed a 120 days incubation experiment to evaluate the effect of soil texture and DPS amount on CO2 emissions. Three different textures were tested: silty clay, sandy-silt and sandy with three DPS doses: 0, 30 and 60 t.ha-1. Results showed that DPS mineralization without soil seemed very rapid with a high mineralized carbon amount (more than 2.500 gC.kg-1DPS), but did not reach the stable phase. For amended soils, soil texture effects are marked at the end of incubation. The cumulative carbon mineralization depended significantly on soil texture and DPS doses with a significant interaction. Among all soils with different dose application, the highest cumulative carbon mineralization was revealed for silty-clay soil by applying 30 t.ha-1 as well as 60 t.ha-1 of DPS. However, the lowest values occurred for sandy soil. Only this latter achieved the stabilization phase after 120 days and therefore stopped CO2 emission. The highest potential mineralization rate (C0) was achieved for silty-clay soil by applying the two DPS doses. The mineralization rate (C0*k) was two times higher for this soil than the sandy soil. The kinetic deviation of carbon mineralization applying the highest DPS doses (60 t.ha-1) is similar for the four studied soils because of C-decomposition blockage. These findings highlight the necessity to consider the combined effects of the DPS amount and soil texture for assessing C release in DPS-amended soils. [ABSTRACT FROM AUTHOR]

Thermal composting is an important and useful way to transfer raw organic matter into value-added product rich in humic substances. Furthermore, thermal composting is a very promising way to reduce deinking paper sludge pollutions, which are difficult to remove. The objective of this study was to investigate the behaviour of the composting process of deinking paper sludge with poultry manure over 14 months. Two composts were used: C1 (70/30: deinking paper sludge/poultry manure) and C2 (50/50: deinking paper sludge/poultry manure). The compost stability and maturity were assessed via physico–chemical and thermal analyses: thermogravimetric analysis, differential thermal analysis and diffuse reflectance infrared Fourier transform spectroscopy. Diffuse reflectance infrared Fourier transform spectroscopy analysis provided chemical information for the presence of aromatic, phenolic, aliphatic and polysaccharidic structures. Thermogravimetry analyses revealed that both deinking paper sludge composts were rich in humic acids. The ratio E4/E6 (fulvic acids/humic acids) was also carried out to characterise the maturity index of composts. After 14 months, the compost C2 is more stable, mature and rich in humic acids than compost C1. Furthermore, the addition of poultry manure to the deinking paper sludge-based composts enhanced the formation of humic substances. From 0 to 14 months of composting, the concentration of polychlorinated biphenyls decreased from 0.2 to 0.1 mg kg−1 and from 0.6 to 0.2 mg kg−1 for C1 and C2, respectively. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of de-inking paper sludge (DPS) and sewage sludge (SS) application on soil properties, and durum wheat growth and yield. A pot experiment was performed on Calcaric cambisol (clCM) and Cromic Luvisol (coLV) soils. Three DPS rates (0, 30, and 60 Mg ha−1) were studied with and without nitrogen fertilizer (280 kg NH4NO3 ha−1). DPS was also mixed with SS at two rates (5 and 10 Mg ha−1) to highlight the benefits of organic nitrogen compared to mineral nitrogen. DPS improved total organic carbon and nitrogen, mineral nitrogen, and soils cation exchange capacity, the 30% rate provided the greatest improvement in both soils. DPS increased grain and root P, K, Ca, and Mg contents in both soils. It also increased wheat straw N, P, Mg, and Ca for the same soil compared to the control. Mixed DPS treatments with nitrogen fertilizer enhanced grain yield by up to 38% and increased root biomass in the studied soils. Thus, DPS is a potential source of organic matter and a liming agent for acid soils when appropriate supplemental fertilizer is provided. [ABSTRACT FROM AUTHOR]

The use of deinking paper sludge (DPS) as a fertilizer instead of sending it to landfill could play a role in reducing greenhouse gases and improving soil properties. The objectives of this study were (1) to evaluate the changes in the physical (permeability and structural stability), chemical (particularly soil pH), and biological (microbial metabolic quotient (qCO2), microbial biomass soil CO2 emissions) of a calcareous agricultural soil following two successive annual amendments with three treatments (0, 30, and 60 Mg DPS ha−1—control, DPS30, and DPS60, respectively); and (2) to determine whether the addition of N-fertilizer to these treatments (controlF, DPS30F, and DPS60F, respectively) causes changes to soil fertility. The DPS application increased soil organic matter (+0.80%: DPS60 vs. control; and +0.35%: controlF vs. DPS60F), available phosphorus (+23.14 mg kg−1: DPS60 vs. control; and +14.34 mg kg−1: DPS60F vs. controlF), potassium (+0.6 g kg−1: controlF vs. DPS30F), and calcium (+0.28 g kg−1: DPS60 vs. control). The 60 Mg DPS ha−1 rate improved permeability and structural stability, regardless of the presence or absence of N-fertilizer. On the other hand, the 60 Mg DPS ha−1 rate without N-fertilizer lead to a decrease in total mineralization rate and qCO2, thereby indicating a reduction in CO2 emissions. The rate of 60 Mg ha−1 DPS could be effectively used to enhance the permeability and stability (soil restoration) and mitigate CO2 emissions, whereas the 30 Mg ha−1 rate could be used as fertilizer to improve the fertility of calcareous soils. [ABSTRACT FROM AUTHOR]