LIFE CYCLE ASSESSMENT OF BIOSSURFACTANTS: A CRITICAL ANALYSIS

Objective: To analyze the environmental performance of biosurfactants in comparison to synthetic surfactant based on the literature. Theoretical Framework: Surfactants are used in various sectors, ranging from domestic uses to industrial applications. Their surface tension reduction properties make them efficient in cleaning and versatile, however they come predominantly from fossil sources. In contrast, biosurfactants constitute a variety of surfactants obtained by microorganisms, including yeasts, bacteria and fungi, from renewable biomass sources. Method: A systematic four-step approach was used, including advanced search, combined strings, screening and reading of abstracts, validation of results and reading and analysis of documents. The inclusion criteria were: use of environmental Life Cycle Assessment (LCA), biosurfactant study and originality. Results: 6 articles were validated and it was verified that for 1 kg of product, biosurfactants present varying environmental impacts depending on the impact categories analyzed and higher values compared to synthetic surfactant. Technological advances in the production of biosurfactants indicate a potential to increase their efficiency, making them competitive with synthetic surfactants. Research implications: This research addresses the scarcity of data on the environmental performance of biosurfactants, encouraging studies to enable their large-scale production. Life Cycle Analysis (LCA) directs technological efforts, aiming at the entry of these products into the commodities market.


INTRODUCTION
Surfactants are amphilic molecules and their use plays a key role in a wide range of industrial and technological applications.Due to their surface tension reduction properties and ability to form micelles, they are widely employed in sectors such as personal care, drugs, pesticides, food and oil (AFOLABI et al., 2022).
Surfactant production in 2023 is approximately 17 million tons per year and most of the volume produced ends up being released as effluent, the growth projection for the years 2021 to 2028 is that the global market for synthetic surfactants will grow at a rate of 4.9%, from 41 billion dollars in 2021 to 58 billion dollars in 2028 (NAGTODE et al, 2023).
Faced with this volume, resolving environmental issues is a crucial issue for a sector that deals with the expansion of environmental regulations, world agreements and customer awareness (Dos Anjos and De Almeida).However, due to the constant use of these surfactants in different contexts, the environmental impacts of these components are often neglected (JOHNSON et al., 2021).
Since the release of the IPCC Special Report "Global Warming 1.5°C" and the Meeting of the Parties (COP) several countries have agreed to take more sustainable attitudes, ensuring that the global average temperature does not exceed 2°C compared to previous levels (NAIDOO, 2022).This public and governmental interest movement leads to the formalization of safer environmental agreements, laws and regulations (DE OLIVEIRA DIAS et al., 2023).Contamination of ecosystems has been progressively associated with sustainability, climate change and various health issues, which sheds light on a regulatory movement that undermines the future market for fossil-based products (JIMOH and LIN, 2019).
With the development of regularizations that impact on higher taxation and lack of incentive to use non-renewable technologies, many companies and research centers are emphasizing renewable artifacts that fulfill functions similar to fossil counterparts.Concurrent with consumer awareness and the formation of a niche market that seeks products of a renewable nature, given the finitude of fossil resources, Ng et al. (2022) highlight the urgency of implementing compatible technologies capable of replacing synthetic surfactants with products that can fully fulfill their functions, while presenting advantages, such as being environmentally sustainable.
Biosurfactants exist naturally in the environment and perform some functions in the ecosystem even without human interference, these natural surfactants can be derived from different types of plants, like coconut and palm (KURUP, 2023).However, only in the last decades have molecules produced from microorganisms with surfactant properties been described and called biological surfactants or biosurfactants (FELIPE and DIAS, 2017).These appear as a promising option, presenting surface properties similar to synthetic surfactants but originating from renewable biological sources (AKBARI et al., 2018).
Biosurfactants are a vast group, composed of a variety of surfactants obtained naturally by microorganisms such as yeasts, bacteria and fungi from renewable resources such as natural oils and carbohydrates (SANTOS et al., 2016).This class of biosurfactant surfactants has attracted increasing interest to replace synthetic surfactants in several applications including pharmaceutical production, cleaning products, advanced recovery and oil production, as well as incorporation in lubricant oil formulations and different solutions for treating environmental problems such as oil spills and bioremediation (BRUMANO; SOLER; DA SILVA, 2016;DURVAL et al., 2020;WANG et al., 2021).
In the year 2020, the market for biosurfactants was estimated at about US$2.5 billion.The global market remains warm, projected to expand at a rate of 5.7% from 2022 to 2027, reaching a value of $3.5 billion by 2026 (NAGTODE et al., 2023).The aforementioned authors raise the hypothesis that the sector is expanding due to the growing demand for biosurfactants made from biomass residues and agricultural raw materials.
As a result of the greater attention given to health, beauty and personal hygiene in recent years, in line with global demands for more environmentally friendly products, leading companies such as Dow, BASF, Unilever, Clarient, Evonik and Croda already present in their portifoils commercial products originating from biosurfactants, either partially or fully, which demonstrates the investment and interest of the big corporations in inserting themselves in this market of biological surfactants (NAGTODE et al., 2023).
One of the challenges for large-scale production of biosurfactants is production cost, as an example, production of purified surfactin powder (mass purity 89%) on an industrial scale is estimated to be between $836.00 and $2059.70/kg(CZINKÓCZKY and NÉMETH, 2020).However, the use of cheaper substrates and new technologies are paving the way for greater productive efficiency, making biosurfactant production promising (BANAT et al., 2014;SINGH;PATIL;RALE, 2019).
Biosurfactants, in general, tend to have some benefits compared with their counterparts produced by chemical routes.Some of the benefits are: wider range of use in different segments, biodegradability, bioavailability, biocompatibility, high selectivity, environmental suitability and better efficiency at high temperatures and salt stresses (AMBAYE et al., 2021).
However, although biosurfactants are pointed out as more environmentally sustainable alternatives, there is a significant gap in the literature about the effective impact of their environmental impacts compared to synthetic surfactants.In addition, large-scale process optimization and cost competitiveness and different applications also pose challenges to the technical and economic viability of biosurfactants (NG et al., 2022).Villota-Paz et al., (2023) point to the need for new approaches regarding the quantification of environmental impacts of products using biosurfactants, requiring the use of reliable tools and further studies focused on this topic.In the last few years, studies have begun to appear that have the purpose of assessing the environmental performance of different biosurfactants, some of them in comparison with other biosurfactants and synthetic surfactants.
In this context, this study aims to analyze environmental performances of biosurfactants, aiming to identify their impacts, highlight opportunities for improvement and foster research on the topic, and, if appropriate, contrast the results with other commercially popular synthetic biosurfactants and surfactants.

THEORETICAL FRAME
This session will present guiding aspects of the research regarding theories and studies on surfactants, biosurfactants and environmental performance evaluation using the Life Cycle Assessment methodology applied to such products.

Surfactants
Surfactants, or surfactants, are chemical compounds widely used mainly for domestic uses, but also in various industrial sectors (MOUSAVI and KHODADOOST, 2019).These compounds represent a class of chemicals that have affinity for polar or apolar substances, and this characteristic is known as amphilic and amphipathic and derives from their particular molecular structure (Figure 1), which means that part of a single surfactant molecule can easily interact with water and the other part has a higher tendency to interact with oily substances (AHMADI, 2020).
This property is responsible for the interest in the use of these substances for the production of detergents and hygiene products around the world.Most of these commercially available compounds are produced from petroleum derivatives (SHABAN; KANG; KIM, 2020).
Surfactants are considered the most relevant components in terms of the functionality and environmental sustainability of the detergent (OTAZU et al., 2022).Between 2021 and 2028, the global surfactant market is expected to grow at an average rate of 4.9 percent, from $41 billion in 2021 to $58 billion in 2028.Surfactant production is approximately 17 million tons annually and most of this volume ends up being released as effluent into the environment (NAGTODE et al., 2023).
The concentration at which the micelles form (mycelization) process begins is called the Critical Micelle Concentration (CMC) and is defined as the minimum surfactant concentration required to reach the lowest surface tension.Upon reaching the CMC, the amphipathic molecules are aggregated with the hydrophilic portions positioned on the outside of the molecule and the hydrophobic portions in the internal direction (Figure 1).
Surfactants are compounds, both organic and inorganic, which have the ability to reduce the surface tension of a liquid or the interfacial tension between two liquids due to their structure consisting of hydrophilic and hydrophobic parts (Figure 1), and the size and shape of hydrophilic and hydrophobic parts determine their properties (PRASAD et al., 2023).Surfactants are considered one of the most critical contributors in detergent composition, as they can largely deplete and damage the micro and macrobiota of the aquatic and terrestrial environment, mainly by reckless disposal in adjacent water bodies, to which there should be a pre-treatment of the surfactant effluents before their disposal.(REBELLO et al., 2020).Because of the wide use of these detergents in human activities, municipal wastewater has indicated a high average surfactant concentration ranging from 10 to 20 mg/L, reaching up to 300 mg/L in industrial effluents (DERESZEWSKA et al., 2015).

Linear Alkylbenzene Sulfonate
The main surfactant of the anion class is the Linear Alkylbenzene Sulfonate (LAS) (FELIPE and DIAS, 2017), whose overall consumption, per year, corresponds to approximately 2.8 × 10 6 tons and this number has steadily increased and, therefore, greater attention must be given to its use and disposition in the environment (MUNGRAY and KUMAR, 2009;ZHOU et al. 2018;HASSANZADEH and JAFARI, 20002002200).
THE LAS (Figure 2) is one of the most widely used surfactants worldwide in the formulation of commercial detergents and in 2018 represented 84% of the market of anionic surfactants because it has a high market acceptance due to the high cleaning potential when compared to ordinary soap, the surfactant Lauril Eter Sulfate Sodium (LES) (JONES-COSTA, 2018;MENEZES et al., 2018).LAS is an anionic surfactant that is widely used in cleaning products, detergents, cosmetics, textiles and other industrial chemicals (FELIPE and DIAS, 2017;PIRETE, 2018).
In spite of being much used, this substance, like so many others produced by man, has a production chain that brings about a series of processes that involve extraction, manufature and transport.These processes, when carried out, generate impacts on the environment, whether by releasing carbon dioxide, consuming water or producing chemical waste (HAUSCHILD; ROSENBAUM; OLSEN, 2018).

Biosurfactants
Biosurfactants are commonly considered as the next generation of industrial surfactants (BACCILE et al., 2017).The interest in biosurfactants is due to their potential environmental advantages, such as higher biodegradability, low toxicity, use of renewable sources and possibility of using residues from other processes as raw material.In addition, biosurfactants may have lower Critical Micellar Concentration (CMC) values, which improves their efficiency in various applications compared to synthetic surfactants (JAHAN et al., 2020).The relationship of CMC and surface tension reduction is presented in Figure 3. Initially, the biosurfactants are introduced into the system and adsorb themselves to the interface between the immiscible phases.This adsorption creates a surface layer that decreases surface tension, facilitating interaction between liquids (step 1).As the concentration of biosurfactants increases, the second step involves the formation of monomers that continue to accumulate at the interface, contributing to the gradual reduction of surface tension.However, it is in the third stage that a crucial point occurs: the critical micellar concentration (CMC).At this point, the formation of micelles becomes more favorable, bringing about a significant and more efficient reduction in surface tension.In the final phase, mycelization and stability are achieved, where the additional addition of biosurfactants results mainly in an increase in the amount of micelles, contributing to the stability of the system (FELIPE e DIAS, 2017; SARUBBO et al., 2022).
In 2020, the biosurfactant market was estimated at about $2.5 billion, the global market is projected to expand at a rate of 5.7% from 2022 to 2027, reaching a value of $3.5 billion by 2026.The sector is expanding due to the growing demand for biosurfactants made from biomass waste and agricultural raw materials (NAGTODE et al., 2023).
In terms of demand per region, the global market for biosurfactants is vast and reaches from the Middle East, Africa, North, South and Central America, Asia Pacific and Europe to Asia (AMBAYE et al., 2021).In Europe, the market for biosurfactants presents an interesting growth factor, mainly due to the high awareness of society, as they consume more biosurfactants to prevent the environmental risks of synthetic surfactants (AMBAYE et al., 2021).Also according to this study, the forecast of growth in demand is optimistic as to the reduction in production costs as a result of technological advances in the production of the biosurfactants.
Latin America is a region with enormous potential due to its enormous biodiversity and the extension of productive agricultural areas, which produce by-products that can be used as substrates for the production of biosurfactants (SEGOVIA-HERNÁNDEZ et al., 2022).Means that incorporate agroindustrial residues have been proposed as substrates to improve the economic viability of large scale production of biosurfactants and make these natural products more competitive, however, despite Brazil being a leader among Latin American countries in the area of biosurfactants, present high indexes of publications and patents, the development of biosurfactants previously in the country remains a challenge, mainly due to the low conversion factors from substrate to product (SANCHES et al., 2021;SARUBBO et al., 2020).These factors, which are being researched and have presented better coefficients throughout research 7 carried out with different residual substrates, different methodologies and increase of bioprocess technologies (FELIX et al., 2019;JANEK et al., 2021;GANESAN and RANGARAJAN, 2023).
Biosurfactants have potential advantages over synthetic surfactants such as biocompatibility, digestibility, efficacy over a wide range of temperatures and pH values, availability of natural sources, adaptability, and antimicrobial activity (JOHNSON et al., 2021).On the other hand, they show that the biosurfactants depend on the cultivation of microorganisms for their production and production technologies not yet consolidated, which result in a higher production cost due to the low productivity.
However, advances in research are necessary for the biosurfactants to have greater competitiveness in the market.The commercial availability of microbial biosurfactants is quite limited due to the difficulties of large scale production, availability of low cost renewable raw materials and optimization of production, recovery and purification technologies (SINGH; PATIL; RALE, 2019).

Life Cycle Assess ent
Life Cycle Assessment (LCA) is a tool that enables you to quantify the environmental impacts arising from a product or service in various categories, making it relevant to the decision making of organizations (FERRARI et al., 2021).However, the lack of reliable data for impact assessment, as well as the difficulty in obtaining such data, associated with the application of impact assessment methods from regions other than the one under study, constitute major challenges for the achievement of LCA (PATOUILLARD et al., 2019;BELKHIR;LOUHAB;BOUGHERARA, 2022).
The environmental performance of a product or process throughout its life cycle can be assessed from the LCA, which consists of analyzing the environmental aspects of a product system according to the system boundaries (SAHOO; BERGMAN; KHATRI, 2021).
It is important to note that life cycle assessment involves the use of data and models subject to uncertainties, such as measurement errors in input data, lack of data representativeness, system boundary determinations, underlying assumptions and gaps in modeling, all of which contribute to variability in results.Therefore, it is crucial to have an understanding of the breadth of this uncertainty when employing LCA results in the decisionmaking process (QIN; CUCURACHI; SUH, 2020).
The literature is full of articles on parameters for the production and optimization of biosurfactant base due to the potential for sustainability involving biosurfactants (AHMADI et al. 2020;JOHNSON et al. 2021) However, studies describing a detailed methodology on potential environmental impacts of biosurfactants are limited in order to identify the effective commitment to sustainability, and further studies using LCA methodology to study synthetic surfactants and biosurfactants are needed (BRIEM et al., 2022).

METHODOLOGY
In order to provide a broad overview of the LCA studies of biosurfactants, a 4-step systematized approach was followed during the research for this study (Figure 4), these are: advanced search, combined search strings, sorting and reading, distinguishing valid results, and reading and analyzing documents.The bibliographic research was conducted in the scientific databases of Scopus and Google Academic and was conducted in November and December 2023.
The components are associated with biosurfactants and LCA studies.To find a larger horizon of studies, expressions were performed in English and in the article title categories, abstract and keywords: "ARTICLE TITLE, ABSTRACT, KEYWORDS" search: "biosurfactant" AND "microbial surfactant" AND "life cycle assessment").
Next, inclusion criteria were defined to identify the relevant documents, being: use of environmental LCA, biosurfactant study and original article.Subsequently, readings of the titles and abstracts of the documents were carried out, accompanied by the analysis of the criterion of inclusion of original articles (case studies), and 7 articles with potential interest for the scope of this study were highlighted.After a complete reading of the articles surveyed, it was observed that 1 of them, despite being a biosurfactant study and containing information about LCA, is a detailed systematic review, and does not perform a LCA for biosurfactants, on account of this, was not considered for discussion of the results obtained.
In the selected LCA studies from the literature consulted, scoping information was highlighted such as: type of surfactant, raw material used, scale of the study, main processes, application, geographical reference, extension of the product system, functional unit, software, database, source of data used, Life Cycle Impact Assessment (LCIA) methods and impact categories.Next, results of AICVs of biosurfactants and surfactants were compared for the production of 1 kg of product.

RESULT AND DISCUSSION
The main information in the scope of LCA studies of biosurfactants was compiled in the Board 1.The study by Baccile et al. (2017) highlights the microbial production of biosurfactants as a promising alternative to petroleum derivatives, due to low toxicity, high biodegradability and biological processes from renewable resources.Despite global limitations, such as low yields and few chemical structures available, the study describes a scalable method of producing 100% acidic soforolipids, reaching 138 g/L.Life cycle analysis reveals similar environmental impact to chemical surfactants derived from fossil resources, the use of rapeseed oil and glucose as substrates is the main reason for the results, with a combined contribution of 78% of the total endpoint score in terms of ecosystem damage and resource damage.Another relevant impact factor is electricity consumption along the chain (15%).Optimizing conversion efficiency and the glucose-rapeseed oil ratio holds the most important improvement potential.In addition, final analysis demonstrates comparable performance for most products except LAS, with potential mitigation through second-generation raw materials and increased efficiency in the production and purification process.
The authors conclude that fermentative glycolipid biosurfactants are alternatives to limited petrochemical surfactants due to lack of structural control and availability of specific congeners (BACCILE et al., 2017).ASL-COOH (T21) is nontoxic, inhibiting bacterial growth and biofilm formation, especially in Gram-positive strains.Acid sophorolipids (aSL-COOH T21) have limited O/W emulsion stabilization but exhibit good foaming and solubilization.Life cycle analysis reveals environmental impact similar to chemical surfactants, with majority influence due to the use of rapeseed oil and glucose.Optimization of conversion efficiency and glucose/rapeseed oil ratio are crucial to reducing impact.In addition, final analysis demonstrates comparable performance for most products except LAS, with potential mitigation through second-generation raw materials and increased efficiency in the production and purification process.
Already in the study by Aru and Ikechukwu (2018), the authors state that the LCA of the biosurfactant production did not show high indices of environmental impacts.However, the energy source of natural gas was the main environmental factor.It is also added that it is necessary to describe the purpose of the manufacture of the surfactant.When the goal is environmental bioremediation, it is logical to place the organisms directly in the soil, since they have the ability to produce exopolymers that have surfactant activities, as well as increase soil fertility.On the other hand, when it comes to the production of biosurfactant, the use of hydroelectric energy should be taken into account, since the supply of electricity was the main contribution of environmental impact.Presenting as conclusions that the LCA presents that the production of biosurfactant did not show high indices of environmental impacts.However, the energy source of natural gas was the main environmental factor.It is necessary to describe the actual purpose of surfactant manufacture, if the objective is environmental bioremediation, it would be logical to place the organisms directly in the soil, since they have the ability to produce exopolymers that have surfactant activities, as well as to increase soil fertility.On the other hand, when it comes to the production of biosurfactant, the use of hydroelectric energy must be taken into account, since the supply of electricity was the main source of pollution.
Authors Kopsahelis et al. (2018) concluded that atmospheric emissions, electricity and heat, during the production of surfactants: soforolipids, ramnolipids, fatty acid ethyl esters (FAEE) and monoglycerides (MAG), are the main contributors to the potential environmental impacts of LCA.Among the biosurfactants, the production of sophorolipids resulted in a 22.7% higher environmental impact compared with the production of ramnolipids in the categories of global warming, ozone depletion, photochemical oxidation, acidification, eutrophication and fossil energy.The authors also point out that the production of FAEE can be classified as a more ecological process compared to the production of MAG, resulting in a 67% lower environmental impact based on the environmental indicators evaluated (the same ones already cited).Environmental impacts due to energy consumption of the studied processes can be mitigated by using renewable energy sources to decrease the environmental footprint.Further analysis of its environmental performance should extend the boundary of the study to encompass crib-to-grave analysis based on data derived from a large-scale production plant.
The study of these authors revealed that air emissions, electricity and thermal requirements during their production are the main contributors to the potential environmental impacts assessed (KOPSAHELIS et al., 2018).Among the biosurfactant production processes, the production of soforolipids resulted in a 22.7% higher environmental impact compared to the production of ramnolipids.Likewise, FAEE production can be classified as a greener process compared to MAG production, resulting in a 67% lower environmental impact based on the environmental indicators assessed.Environmental impacts due to energy consumption of all processes studied can be mitigated by using renewable energy sources to decrease the environmental footprint.A more in-depth analysis of its environmental performance and potential future work could extend the study to include all cradle-to-grave analysis based on data derived from a large-scale production plant.
Elias et al. ( 2021) evaluated two distinct processes of biosurfactant production from sugarcane bagasse, verifying economic viability and environmental footprint in an integrated plant with ethanol production.Both processes showed favorable economic performance, with the second option (liquid pre-treatment with hot water without detoxification and double ultrafiltration in cane bagasse) superior in economic and environmental terms.The sensitivity and uncertainty analysis revealed that the second scenario was 59.7% likely to reach a minimum selling price of biosurfactant below 20 US$/kg, highlighting its economic advantage.In this scenario, the time and volume of the pre-treatment reator, ultrafiltration flow and membrane operation are relevant, which highlights the need to optimize economic and environmental aspects in the production of biosurfactants from sugarcane bagasse.
The aforementioned study points out that two processes have been proposed to produce biosurfactants from sugarcane bagasse, evaluating economic viability and environmental footprint in an integrated plant with 1G ethanol production.Both processes showed positive economic performance, with the second option (liquid pre-treatment with water without detoxification and double ultrafiltration in sugarcane bagasse) superior in economic and environmental terms.The sensitivity and uncertainty analysis revealed that the second scenario was 59.7% likely to reach a minimum selling price of biosurfactant below 20 $/kg, highlighting its economic advantage.Critical process variables include reaction time, volume of the bioreactor, and final concentration of biosurfactant in both cases.For the second scenario, the time and volume of the pre-treatment reactor, ultrafiltration flow, and membrane operation are relevant.These considerations highlight the need to optimize economic and environmental aspects in the production of biosurfactants from sugarcane bagasse.
The preliminary study developed by Hu et al. (2021) selected first and second generation raw materials to produce 1 g/L of sophorolipids (SL) and identified food waste as the most advantageous source.However, the evaluation and optimization of pilot scale production faced challenges due to the lack of data and processing information on a laboratory scale.The subsequent study by Hu et al. (2021a) involved a dynamic life cycle assessment (dLCA) of the production of sophorolipids from food waste on an industrial scale, revealing that fermentation with discontinuous feeding was the most harmful step.Also on this study, the combined analysis of LCA and technical-economic analysis explored ways of producing crystals and SL syrup, indicating that SL crystals have higher environmental impacts and total costs, while SL syrup is more suitable for applications with less stringent requirements of toxicity and purity.
Overall, this study selected first and second generation raw materials to produce 1 g L -1 of SL (HU et al., 2021a).Food waste has been identified as the most advantageous source.The optimization of batch fermentation of food waste resulted in the production of 1 kg of raw SLs, considered the most sustainable option.However, the evaluation and optimization of pilot scale production faced challenges due to the lack of data and processing information on a laboratory scale.Improvements in the recovery of refined SL are needed on an industrial scale before marketing, considering environmental and financial implications.The third stage, developed in this article, involved a dynamic life cycle (dLCA) of the production of sophorolipids from food waste on an industrial scale, revealing that discontinuous fermentation fed was the most harmful stage.A combined LCA analysis and techno-economic analysis explored crystals and SL syrup production pathways, indicating that SL crystals have higher environmental impacts and total costs, while SL syrup is more suitable for applications with less stringent toxicity and purity requirements.
Finally, the study by Schonhoff et al. ( 2022) is a LCA that compares the environmental impacts of the production of rhamnolipids (RL) and Manosileritritol lipids (MEL), from molasses and sugar beet pulp respectively, to conventional surfactants.The recovery of RL precipitation and first HONEY extraction have greater impacts on the assessed categories, driven mainly by the inputs involved.The most relevant impact categories are: for RL, "Resource use, fossils", and for HONEY, "Ecotoxicity, freshwater -total" and "Climate change -total".HONEY has lower impacts than RL in which the use of molasses has less effect, however, the choice of substrate did not influence much.The study concluded that biosurfactant production is competitive and can be enhanced with technological advances, requiring improvements in aeration, waste use and recycling of inputs.The study highlights that LCA supports the identification of the environmental viability of innovative RL and HONEY biosurfactant production processes substitutes for synthetic surfactants.
As a conclusion, the article highlights the analysis of the environmental benefits of producing RL and HONEY biosurfactants from molasses and sugar beet pulp compared to conventional surfactants (SCHONHOFF et al., 2022).Crucial stages include fermentation and beet production/processing.Waste treatment, compressed air supply and fertilizer production are essential steps.Rainfall recovery (RL) and process extraction (MEL) have higher impacts, driven mainly by the supply of agents.The most relevant impact categories are "Resource use, fossils" (highest RL contribution), "Ecotoxicity, freshwater -total" (highest MEL contribution) and "Climate change -total".The focus on the target product is crucial, with HONEY showing lower impacts than RL.The use of molasses has less effect, but the choice of substrate does not influence much.The production of biosurfactants is competitive and can be reinforced with technological advances.Improvements such as aeration, waste use, and agent recycling are important.These results indicate that LCA supports the environmental viability of innovative RL and HONEY biosurfactant production processes as substitutes for traditional surfactants.
The studies presented are of different classes of biosurfactants, but present relevant results for the literature, mainly due to the scarcity of scientific research using consolidated methodologies for quantifying environmental impacts, as Briem et al. ( 2022  It can be seen that, considering the same declared unit, the biosurfactants had varied environmental impacts in the impact categories analyzed (Table 1).This is due to the distinctions between the processes involved in the production of biosurfactants, as well as different substrates, raw materials used in the fermentation medium, use of utilities such as electricity, long air, steam, as well as different conversion factors for each product.A direct comparison of the declared 1 kg unit of each product is also perceived, indicating that the synthetic commercial surfactant LAS has a lower environmental impact in most of the categories analyzed (global warming, fossil energy, ozone depletion, ecotoxicity and total human toxicity).
However, assuming that the amount of surfactant used is related to its surface tension reducing power, according to (SCHONHOFF et al., 2022), it is feasible to establish a functional unit that considers specific cleaning performance (SCP) from the critical micellar concentration (CMC).Since surface tension will not be reduced beyond the CMC point, the CMC specifies exactly the appropriate concentration for use (specific surfactant mass per volume (g/L)).This characteristic points to the need to consider the functionalities of these surfactants for a more reliable comparison, mainly because microbial surfactants are more effective and efficient in their CMC (RODRIGUES, 2015).Therefore, it tends to require less biosurfactant to obtain a decrease in surface tension compared to the synthetic surfactant.
The authors Kłosowska-Chomiczewska et al. ( 2017) present a CMC value of 62.1 mg/L for a ramnolipid obtained from glycerol, while the LAS presents a CMC of 11 mg/L (BOGNOLO, 1999).According to the findings made by Schonhoff et al. ( 2022), for the results presented in (Table 1) It is possible to highlight that for the same SCP, approximately 6 kg of LAS is required to perform the same function as 1 kg of "Ramnolipid_Melaço".This means that the environmental impacts of biosurfactants with higher CMC tend to be closer to those of the synthetic surfactant in the categories analyzed.In this way, technological advances in the production of biosurfactants at more efficient levels make them more sustainable and commercially competitive, even with the synthetic surfactants established in the market.

CONCLUSION
This work highlights that the Life Cycle Assessment (LCA) methodology has proven to be able to guide this environmental performance assessment among surfactants.An identification of the available studies in the literature of LCA of biosurfactants was performed to analyze their scope and environmental impacts in comparison to the synthetic surfactant Linear Alkylbenzene Sulfonate (LAS).
The main players in the sanitation market tend to demand more products that use biological surfactants.In addition, new technologies have been developed with promising results that impact the expansion potential of the biosurfactant market.This suggests that, in a future perspective, biosurfactants may compete with synthetic surfactants in the commodities market.
Biosurfactants are proving competitive in the face of environmental performance, even though there are technological challenges for large scale production in an optimized manner that guarantees greater efficiency.Therefore, more studies with an emphasis on the environmental impacts of surfactants are necessary to map the classes and types of biosurfactants that have a lower environmental impact in the life cycle of their production, making them competitive against the synthetic ones that are optimized and established in the market.

Figure 1 -
Figure 1 -Representation of a surfactant in a polar and apolar environment Source: Felipe e Dias, 2017

Figure 3 -
Figure 3 -Steps in the reduction of surface tension as a function of the addition of biosurfactant until reaching the critical micellar concentration (CMC) and formation of micelles Source: Adapted by Sarubbo et al., 2022

Figure 4
Figure 4 Systematized approach to the methodology for searching for Life Cycle Assessment (LCA) studies for biosurfactants Source: The authors ) points out.The importance of comparing LCIA values is highlighted with the results obtained in this study.Even if the studies have different scopes, a comparison of the declared unit of 1 kg of product (without considering its function), which is used in most studies, supports a preliminary comparison between biologically-based surfactants and synthetic surfactants, which highlights the challenges and opportunities for progress towards sustainability in the sanitation sector.A Erro! Fonte e referência n o encontra a. presents the comparison of the LCA of biosurfactants raised in this study along with the impacts of LAS (market for alkylbenzene sulfonate, linear, petrochemical | alkylbenzene sulfonate, linear, petrochemical | Cutoff, U") available in the Ecoinvent 3.8 database in the OpenLCA 2.0.0 software.

Table 1 .
-LifeCycle Impact Assessment (LCIA) Comparison of Biosurfactants and Synthetic Surfactant for Production of 1 kg of Product Source:The authors