Search

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.

The growing shortage of essential nutrients, such as nitrogen and phosphorous, is prompting researchers to find advanced recovery processes from wastewater derived from sewage treatment plants and other wastewater sources. In this work we propose a novel compostable electrospun filtration membrane based on poly(L-lactic acid) (PLLA), for nutrient recovery through struvite crystallization from water. Composite electrospun PLLA fibers were fabricated starting from a suspension of PLLA solution and struvite crystals. Struvite within PLLA fibers worked as a nucleant agent for additional crystallization of magnesium, ammonium and phosphate hexahydrate out of water. Morphological, structural and physical properties of the obtained membranes were studied and the ammonium concentration decrease in the analyzed water samples was measured and correlated to struvite precipitation on the electrospun membranes. The obtained compostable struvite-rich membrane can be used in agriculture to provide a nutrient-rich humus for direct application to the land.

Research on the anaerobic treatment of raw cheese whey started in 1990 with the objective of developing a technology suitable for medium size cheese factories that have growing disposal problems and cannot afford high investment costs for whey valorisation technologies (such as whey protein and lactose recovery, spray drying, etc.). In order to couple process stability and high loads, a new downflow-upflow hybrid reactor (DUHR) has been designed. The reactor was able to reach Bv values around 10 g COD·1−1·d−1, with 98% COD converted to gas and effluent soluble COD values close to 1,000 ppm; no external addition of alkalinity is required to maintain a stable pH that was constantly around 6.5-6.7 in the downflow pre-acidification chamber and around 7.5 in the bio-methanation upflow chamber. The high strength of the cheese whey treated gives an effluent that still contains high amounts of COD, ammonia nitrogen and phosphorus and therefore a post treatment is required in order to meet standard limits. Tests of post treatment were carried out during two years with a Sequencing Batch Reactor (SBR). The SBR was tested at various F/M values with different durations of anoxic-anaerobic-oxic cycles, obtaining, under certain conditions, more than 90% removal of COD, nitrogen and phosphorus.

Many industrial effluents, such as textile and tannery wastewater, contain slowly biodegradable, refractory or even toxic compounds at variable concentrations which may interfere with the efficient operation of biological wastewater treatment plants, in particular with the nitrification stage. Agro-industrial effluents may occasionally contain sanitising agents which are by definition biocides. Two different biosensors, based on respirometry (oxygen uptake rate, OUR measurements) and on basic titration respectively, were used to measure degradation rates of industrial wastewater samples by autotrophic bacteria (ammonia oxidizers). Specific sanitisers such as sodium hypochlorite and benzalconium chloride were used to evaluate and compare the nitrifying activity measured by the two different instruments.

Research on the anaerobic treatment of raw cheese whey started in 1990 with the objective of developing a technology suitable for medium size cheese factories that have growing disposal problems and cannot afford high investment costs for whey valorisation technologies (such as whey protein and lactose recovery, spray drying, etc.). In order to couple process stability and high loads, a new downflow-upflow hybrid reactor (DUHR) has been designed. The reactor was able to reach Bv values around 10 g COD·1−1·d−1, with 98% COD converted to gas and effluent soluble COD values close to 1,000 ppm; no external addition of alkalinity is required to maintain a stable pH that was constantly around 6.5-6.7 in the downflow pre-acidification chamber and around 7.5 in the bio-methanation upflow chamber. The high strength of the cheese whey treated gives an effluent that still contains high amounts of COD, ammonia nitrogen and phosphorus and therefore a post treatment is required in order to meet standard limits. Tests of post treatment were carried out during two years with a Sequencing Batch Reactor (SBR). The SBR was tested at various F/M values with different durations of anoxic-anaerobic-oxic cycles, obtaining, under certain conditions, more than 90% removal of COD, nitrogen and phosphorus.