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Although the biodegradability of compostable bioplastic bags (CBBs) is well ascertained, concerns arise about the possibility of treating a massive quantity of compostable materials in composting facilities of all sizes and configurations. These concerns are even greater in small-scale composting where the biodegrading conditions may be milder that those in industrial composting. In this work, 7–15 lightweight CBBs were disposed of, together with organic food waste, in an electromechanical composter (EMC), every day for about 2 months. For the bulking agent, fragments and twigs of golden wattle wood were used instead of the recommended wood pellets. The composting process was carried out for 3 months in the EMC, and for further 4 months in a heap, in order to complete the maturation. During the process, critical issues in general, and any due to the presence of the CBBs, were reported: high temperatures, up to 72 °C, were constantly reached both in the ECM and in the heap, while critical anaerobic pockets were not detected. After 7 months, when the temperature and pH of the heap were equal to the ambient temperature and to 7.4, respectively, and were constant over time, the process was stopped and the compost produced underwent chemical, physical and biological analysis, in order to evaluate its quality. The CBBs did not produce any visual contamination of the final compost with bioplastic residues. Finally, all the stability, environmental and agronomic parameters were in compliance with the reference values established by law. This work shows how lightweight CBBs are perfectly managed by the EMC, at least with a CBB/organic waste mass ratio that is consistent with a normal use of CBBs as the collector of organic waste. [ABSTRACT FROM AUTHOR]

Development of high-value horticultural markets for compost requires improved characterization of compost properties. Most composts have pH of 7-8 and act as a partial substitute for lime in potting media. The objective of this research was to develop and validate a reproducible method for determining the pH buffering capacity of compost. To estimate compost buffering capacity (CBC), the quantity of acidity needed to reduce pH by one unit, dilute sulfuric acid (HSO; 0.1-1.0 mol H/kg compost) was allowed to equilibrate with compost at 22 °C for 72 h. The CBC was calculated as the negative reciprocal of the slope of the linear regression: compost pH (y-axis) versus acid addition rate (x-axis). The CBC for eight composts ranged from 0.21 to 0.45 mol H per kg compost per pH unit (avg = 0.31). The CBC determined from dilute acid addition for 72 h was validated via incubation of compost plus S° dust at 22 °C for 28 days. For the eight composts evaluated, S° addition to acidify compost by 1 pH unit (as predicted by CBC) resulted in an actual pH decline of 1.1 units (SE = 0.2), and predicted S° addition to acidify it by 2 pH units resulted in an actual decline of 1.7 units (SE = 0.2). The CBC test method is recommended for evaluation by commercial compost testing laboratories. [ABSTRACT FROM AUTHOR]

Phytoremediation is a promising green technology for the remediation of various industrial effluents. Notably, aquatic plants are widely applied to remove dyes and toxic metals from polluted environments. In the present study, the phytoremediation potency of aquatic macrophytes such as Pistia stratiotes L, Salvinia adnata Desv, and Hydrilla verticillata (L.f) Royle were assessed based on the removal capability of pollutants from dyeing effluent. Physicochemical characterizations were carried out for industrial wastewater collected from a cotton material dyeing unit located in the Karur District of Tamilnadu, India. The physicochemical characteristics of the dyeing effluent, such as color, odor, pH, total dissolved solids (TDS), alkalinity, acidity, chloride, sulfate, phosphate, nitrate, chemical oxygen demand (COD), fluoride, and toxic metal levels were determined. The core parameters such as total dissolved solid (TDS), chemical oxygen demand (COD), and chloride level were determined and found to be 6500 mg/L, 2400 mg/L, and 2050 mg/L, respectively, which exceeded the regulatory limit prescribed by the Central Pollution Control Board of India. The levels of toxic metals such as Hg, Ni, and Zn were under the acceptable concentration but Cr and Pb levels in the dyeing effluent were a little bit higher. The effluent was subjected to treatment with Pistia stratiotes L, Salvinia adnata Desv and Hydrilla verticillata (L.f) Royle separately. After the treatment, the toxic metal results were recorded as below detectable levels and the same results were obtained for all three aquatic plants samples used for treatment. Among the three plants, P. stratiotes L efficiently removed 86% of color, 66% of TDS, 77% of COD, and 61.33% of chloride. The variation in phytochemicals of the macrophytes was studied before and after treatment using GC–MS which revealed the reduction of ascorbic acid in the plant samples. The toxic effect of treated effluent was investigated by irrigating an ornamental plant, Impatiens balsamina L. The plant biomass P. stratiotes L obtained after the treatment process was subjected to manure production and its nutrient quality was proved, which can be applied as a soil conditioner. Among the aquatic plants, the results of P. stratiotes L indicated a higher remediation potential, which can be used as an ecologically benign method for treatment of industrial effluents and water bodies contaminated with dyeing effluents. [ABSTRACT FROM AUTHOR]