Environmental water contamination is a relevant issue of major concern for ecosystems preservation. Water is the basis of life-supporting processes and a mandatory need for human and other living organisms. Therefore, water should be safe, easily accessible, adequate and free of contaminants. The presence of pollutants in water bodies can have serious consequences for human health and aquatic ecosystems. They can be classified into different types, including inorganic pollutants, organic pollutants, pathogens, and radioactive pollutants. A major source of water bodies contaminations can be attributed to the increase of global industrialisation and intensive agriculture besides inefficient or insufficient water waste treatment plants. The main pollutants are heavy metals, persistent organic pollutants and pesticides. The concentration in water bodies of well-known contaminants is adequately regulated. However, there are emerging contaminants (e.g. plasticizers, pharmaceuticals, pesticides, surfactants, etc.) contained in everyday products which have attracted the researchers and society attention all around the world due to their emerging as well as potential adverse impacts on the environment. Several conventional water remediation techniques are used to remove pollutants in water, particularly in wastewater treatment plants, which are the main cause of the dispersion of contaminants into the environment. For example, chemical precipitation is a cost-effective process but produces large volumes of sludge residues; coagulation-flocculation is a faster process than precipitation, but sludge disposal remains a problem; membrane filtration is an efficient process but is expensive and susceptible to fouling. On the other hand, advanced oxidation processes (AOPs) is highly efficient and does not produce sludge, but is expensive due to high energy consumption, and adsorption is highly efficient and selective but the materials are often very expensive. Research work can support the development of these techniques by studying sustainable solutions to limit or eliminate disadvantages of these processes. The preservation and remediation of the environment could be obtained applying correct practices in agri-food activities, especially through the reuse of waste. In fact, a waste, if adequately treated, may become a valuable resource, such as soil conditioner, food additive or source of relevant chemicals that can be extracted and/or converted into suitable materials for water remediation applications. The present work focuses particularly on the recovery of marine biomass, such as mollusc shells and macroalgae. To better understand how a particular waste can be exploited in a sustainable way, it is essential to study the material through chemical and biochemical characterisation. This evaluation allows to identify which components are relevant for each biomass investigated; for example, calcium carbonate is the major component of oyster shells, or polysaccharides in case of macroalgae. Biomass can be converted in novel, low cost and eco-friendly adsorbent materials through several processes such as chemical synthesis, pyrolysis, chemical and activation; these new materials can then be applied for remediation of polluted wastewater. To this end, biogenic calcium carbonate from mollusc shells waste and biochar from algae polysaccharides were studied as adsorbents of water pollutants or as precursors for the synthesis of novel and sustainable adsorbent materials. In addition, an AOP was applied to the remediation of water contaminated by emerging contaminants. In summary, the aim of this work is the evaluation of the possible reuse of biomass waste resulting from aquaculture and agriculture activities to convert it into new resources, particularly from an environmental perspective, and explore novel solutions for water remediation applications through adsorption as well as photodegradation.
La contaminazione di acque è una questione rilevante per la preservazione degli ecosistemi. L'acqua è la base dei processi vitali, una necessità imprescindibile per gli altri organismi viventi. Pertanto, l'acqua dovrebbe essere sicura, facilmente accessibile e priva di contaminanti. La presenza di inquinanti nei corpi idrici può avere conseguenze gravi per la salute umana e per gli ecosistemi acquatici. Questi inquinanti possono essere classificati in diverse tipologie, tra cui, inquinanti inorganici, inquinanti organici, agenti patogeni e inquinanti radioattivi. Tra le principali fonti di contaminazione dei corpi idrici vi è all'aumento della industrializzazione globale e dell'agricoltura intensiva, oltre che a impianti di trattamento delle acque reflue inefficienti o insufficienti. Tra i principali inquinanti vi sono i metalli pesanti e gli inquinanti organici persistenti. La concentrazione di contaminanti noti nei corpi idrici è adeguatamente regolata. Tuttavia, esistono contaminanti emergenti (ad esempio plastificanti, farmaci, ecc.) contenuti in prodotti di uso quotidiano che hanno attirato l'attenzione dei ricercatori e della società a livello globale per i loro impatti potenzialmente negativi sull'ambiente. Gli impianti di trattamento delle acque reflue utilizzano diverse tecniche convenzionali. Ad esempio, la precipitazione chimica è un processo economico ma produce grandi volumi di fanghi residui; la coagulazione-flocculazione è un processo più rapido della precipitazione, ma la gestione dei fanghi rimane un problema; la filtrazione a membrane è un processo efficiente ma costoso e soggetto a ostruzioni. D'altra parte, i processi di ossidazione avanzata (AOPs) sono molto efficienti e non producono fanghi, ma sono costosi a causa dell'alto consumo energetico, mentre l'adsorbimento è altamente efficiente e selettivo, ma i materiali sono spesso molto costosi. Il lavoro di ricerca può supportare lo sviluppo di queste tecniche studiando soluzioni sostenibili per limitare o eliminare gli svantaggi di questi processi. La conservazione e la bonifica dell'ambiente possono essere ottenute applicando pratiche corrette nelle attività agro-alimentari, in particolare attraverso il riutilizzo dei rifiuti. Infatti, un rifiuto, se trattato adeguatamente, può diventare una risorsa preziosa, come ammendante per il suolo, additivo alimentare o fonte di sostanze chimiche rilevanti che possono essere estratte e/o convertite in materiali idonei per applicazioni di bonifica delle acque. Il presente lavoro si concentra in particolare sul recupero di biomassa marina, come conchiglie di molluschi e Pag. 2 a 2 macroalghe. Per comprendere meglio come un particolare rifiuto possa essere sfruttato in modo sostenibile, è essenziale studiare il materiale attraverso una caratterizzazione chimica e biochimica. Queste valutazioni permettono di identificare i componenti rilevanti; ad esempio, il carbonato di calcio è il componente principale delle conchiglie di ostrica, o i polisaccaridi nel caso delle macroalghe. La biomassa può essere convertita in nuovi materiali adsorbenti a basso costo ed eco-compatibili attraverso diversi processi come sintesi chimica, pirolisi; questi nuovi materiali possono poi essere utilizzati per la bonifica delle acque reflue contaminate. A tal fine, sono stati studiati il carbonato di calcio biogenico dai rifiuti di conchiglie di molluschi e il biochar dai polisaccaridi delle alghe come adsorbenti di inquinanti nell'acqua o come precursori per la sintesi di nuovi materiali adsorbenti sostenibili. Inoltre, è stato applicato un AOP per la bonifica delle acque contaminate da contaminanti emergenti. In sintesi, l'obiettivo di questo lavoro è la valutazione del possibile riutilizzo dei rifiuti di biomassa derivanti da attività di acquacultura e agricole per convertirli in nuove risorse, esplorando soluzioni innovative per la bonifica di acque contaminate attraverso l'adsorbimento e la fotodegradazione.
Reuse of agri-food waste for environmental applications
CESCON, Mirco
2025
Abstract
Environmental water contamination is a relevant issue of major concern for ecosystems preservation. Water is the basis of life-supporting processes and a mandatory need for human and other living organisms. Therefore, water should be safe, easily accessible, adequate and free of contaminants. The presence of pollutants in water bodies can have serious consequences for human health and aquatic ecosystems. They can be classified into different types, including inorganic pollutants, organic pollutants, pathogens, and radioactive pollutants. A major source of water bodies contaminations can be attributed to the increase of global industrialisation and intensive agriculture besides inefficient or insufficient water waste treatment plants. The main pollutants are heavy metals, persistent organic pollutants and pesticides. The concentration in water bodies of well-known contaminants is adequately regulated. However, there are emerging contaminants (e.g. plasticizers, pharmaceuticals, pesticides, surfactants, etc.) contained in everyday products which have attracted the researchers and society attention all around the world due to their emerging as well as potential adverse impacts on the environment. Several conventional water remediation techniques are used to remove pollutants in water, particularly in wastewater treatment plants, which are the main cause of the dispersion of contaminants into the environment. For example, chemical precipitation is a cost-effective process but produces large volumes of sludge residues; coagulation-flocculation is a faster process than precipitation, but sludge disposal remains a problem; membrane filtration is an efficient process but is expensive and susceptible to fouling. On the other hand, advanced oxidation processes (AOPs) is highly efficient and does not produce sludge, but is expensive due to high energy consumption, and adsorption is highly efficient and selective but the materials are often very expensive. Research work can support the development of these techniques by studying sustainable solutions to limit or eliminate disadvantages of these processes. The preservation and remediation of the environment could be obtained applying correct practices in agri-food activities, especially through the reuse of waste. In fact, a waste, if adequately treated, may become a valuable resource, such as soil conditioner, food additive or source of relevant chemicals that can be extracted and/or converted into suitable materials for water remediation applications. The present work focuses particularly on the recovery of marine biomass, such as mollusc shells and macroalgae. To better understand how a particular waste can be exploited in a sustainable way, it is essential to study the material through chemical and biochemical characterisation. This evaluation allows to identify which components are relevant for each biomass investigated; for example, calcium carbonate is the major component of oyster shells, or polysaccharides in case of macroalgae. Biomass can be converted in novel, low cost and eco-friendly adsorbent materials through several processes such as chemical synthesis, pyrolysis, chemical and activation; these new materials can then be applied for remediation of polluted wastewater. To this end, biogenic calcium carbonate from mollusc shells waste and biochar from algae polysaccharides were studied as adsorbents of water pollutants or as precursors for the synthesis of novel and sustainable adsorbent materials. In addition, an AOP was applied to the remediation of water contaminated by emerging contaminants. In summary, the aim of this work is the evaluation of the possible reuse of biomass waste resulting from aquaculture and agriculture activities to convert it into new resources, particularly from an environmental perspective, and explore novel solutions for water remediation applications through adsorption as well as photodegradation.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
