Sustainable Solutions for Environmental Pollution

Здесь есть возможность читать онлайн «Sustainable Solutions for Environmental Pollution» — ознакомительный отрывок электронной книги совершенно бесплатно, а после прочтения отрывка купить полную версию. В некоторых случаях можно слушать аудио, скачать через торрент в формате fb2 и присутствует краткое содержание. Жанр: unrecognised, на английском языке. Описание произведения, (предисловие) а так же отзывы посетителей доступны на портале библиотеки ЛибКат.

Sustainable Solutions for Environmental Pollution: краткое содержание, описание и аннотация

Предлагаем к чтению аннотацию, описание, краткое содержание или предисловие (зависит от того, что написал сам автор книги «Sustainable Solutions for Environmental Pollution»). Если вы не нашли необходимую информацию о книге — напишите в комментариях, мы постараемся отыскать её.

Environmental pollution is one of the biggest problems facing our world today, in every country, region, and even down to local landfills. Not just solving these problems, but turning waste into products, even products that can make money, is a huge game-changer in the world of environmental engineering. Finding ways to make fuel and other products from solid waste, setting a course for the production of future biorefineries, and creating a clean process for generating fuel and other products are just a few of the topics covered in the groundbreaking new first volume in the two-volume set, 
.
The valorization of waste, including the creation of biofuels, turning waste cooking oil into green chemicals, providing sustainable solutions for landfills, and many other topics are also covered in this extensive treatment on the state of the art of this area in environmental engineering. 
This groundbreaking new volume in this forward-thinking set is the most comprehensive coverage of all of these issues, laying out the latest advances and addressing the most serious current concerns in environmental pollution. Whether for the veteran engineer or the student, this is a must-have for any library.

Sustainable Solutions for Environmental Pollution — читать онлайн ознакомительный отрывок

Ниже представлен текст книги, разбитый по страницам. Система сохранения места последней прочитанной страницы, позволяет с удобством читать онлайн бесплатно книгу «Sustainable Solutions for Environmental Pollution», без необходимости каждый раз заново искать на чём Вы остановились. Поставьте закладку, и сможете в любой момент перейти на страницу, на которой закончили чтение.

Тёмная тема
Сбросить

Интервал:

Закладка:

Сделать

In response, selective fermentation (SF) has been implemented as a new approach for enhancing lipid extraction for microalgae biofuel generation (i.e., biodiesel) (Lai et al ., 2016b). SF utilizes the fact that lipids are generally biodegraded more slowly than carbohydrates and proteins under an anaerobic environment (Lai et al ., 2016b; Rittmann and McCarty, 2001; Siegert and Banks, 2005), in which, the lipid fermenters, known as the slow-growing microbes (Christ et al ., 2000; Rittmann and McCarty, 2001), can be washed out of the system with a relatively short solids retention time (SRT) (Lai et al ., 2016b). Hence, the SF solely allows the removal of carbohydrates and proteins in microalgae cells, leaving the lipids intact, providing a state much easier to extract lipids (Lai et al ., 2016b). More importantly, the SF process can significantly promote the lipid extraction process (e.g., >5000-fold increase vs. untreated biomass) when using the hexane-isopropanol solvents (Lai et al ., 2016a). Moreover, the lipid extraction is also benefitted by SF due to biohydrogenation, where the dominant lipid groups on long-chain fatty acids (LCFAs) are converted to saturated forms (e.g., C18:1 to C18:0) (Liu et al ., 2019); the SF process can increase the saturation ratio of extracted lipids by up to 80% (Liu et al ., 2020c). This saturating process via SF for the LCFAs is highly desirable as they can aid the transportation fuel generation due to more energy value, higher octane number (e.g., better combustion efficiency), and greater resistance to oxidation (Knothe, 2011). Also, SF biohydrogenation is superior to the catalytic hydrogenation (e.g., requires high temperature and metal catalysts to operate) due to significantly less or no energy/ catalyst demand (McArdle et al ., 2011; Plourde et al ., 2004; Wang et al ., 2017). Figure 1.5shows a conceptual schematic of lipid extraction from microalgae using electro-selective fermentation.

However, the SF itself can suffer from the fact that the protein fermentation is slower than the carbohydrate fermentation (Lu et al ., 2010). Furthermore, accumulation of short-chain carboxylates (e.g., high COD in the system) is another challenge (Lai et al ., 2016b), resulting in the following two cases: (1) wasting the electrons from the feed biomass (e.g., not all the electrons are used up or recovered as value-added products); and (2) lowering pH, which inhibits the fermentation process (Siegert and Banks, 2005). Hence, stimulating the protein and SCFAs biodegradation is of great interest to assist lipid extractions. Previous studies have reported that MECs have the potential to accelerate the fermentation of protein along with other complex organics, such as SCFAs (Lu et al ., 2012; Velasquez-Orta et al ., 2009). Furthermore, with the increased removal of protein, hydrogen bonds between membrane proteins and lipids can be disrupted, rupturing the cell membrane and exposing intracellular lipids for much simpler extraction (Cooney et al ., 2009; Sheng et al ., 2011). Hence, this was the main motivation behind coupling MEC with SF, also known as the electro-selective fermentation (ESF), to significantly enhance lipid wet-extractions (Liu et al ., 2019; Liu et al ., 2020b; Liu et al ., 2020c).

Recently, several studies have successfully demonstrated superior lipid extraction from microalgae using the ESF (Liu et al ., 2019; Liu et al ., 2020b; Liu et al ., 2020c). Liu et al . (2019) first investigated the relative performance of ESF compared to SF, in terms of protein and COD removal. When the ESF and SF (Control) reactors were fed with microalgae biomass ( Scenedesmus acutus ), significant differences were found in TCOD removal (12% vs. 2%), TCOD-to-SCOD conversion (17% vs. 11%), and protein biodegradation (42% vs. 10%) for ESF and SF, respectively. Interestingly, although the anodic respiration only contributed to < 1% of the total electron input, the ESF system yielded much higher protein and COD degradations. More importantly, even with the greater loss of total lipids due to β-oxidation-linked-to-biohydrogenation (e.g., shifting LCFAs from C18:1 to C16:0 or C14:0) in the ESF system, it still demonstrated significantly higher lipid yields (37%) compared with the SF (12%) and the lipid extractions with hexane-isopropanol solvents (~4%). In summary, despite currently being a small component of overall COD balance, ESF exhibited superior hydrolysis of protein of microalgae biomass ( Scenedesmus acutus ), a higher saturation ratio of LCFA, and higher lipid yields (~3 folds) over SF (Liu et al ., 2019). On the other hand, Liu et al . (2020c) have introduced a flat-plate MEC based ESF to observe the performance in lipid extraction by having a large anode surface area for electroactive bacteria biofilm. The benefit was in the enhanced electron consumptions, where the electrons in the microalgae biomass were greatly scavenged by electroactive bacteria in the anode biofilm. Furthermore, the SCFAs were also efficiently converted to current (e.g., preventing the accumulation of SCFAs), maintaining the optimal working environment (e.g., preventing pH drop) for the fermentation process. Compared with Liu et al . (2019), the ESF significantly improved in microalgae lipid extraction, achieving 56% (vs. 37%) extraction from the total lipids.

Figure 15 A conceptual schematic showing lipid extraction from microalgae - фото 7

Figure 1.5 A conceptual schematic showing lipid extraction from microalgae using electro-selective fermentation. The figure is drawn with modification after Liu et al . (2019).

Finally, Liu et al . (2020b) have compared various SRTs on the ESF performance. In their study, ESF systems with different SRTs were compared (System A: start with a 6 d SRT, then switch to 2 d SRT vs. System B: start with a 2 d SRT, then switch to 6 d SRT). The ESF system A exhibited the highest lipid extractability (25%) when operated with a 6 d SRT, and gave the highest lipid productivity (450 mg/L/d) when switched to a 2 d SRT. This was attributed to establishing the microbial community containing protein fermenters at a 6 d SRT and washing out of lipid fermenters when the system A was switched to the 2 d SRT. Opposingly, the system B failed to enhance the lipid extractability. It initially (e.g., at a 2 d SRT) washed out the lipid fermenters, but it was unable to recover them when the system switched to a 6 d SRT. Ultimately, demonstrated by multiple studies, the further studies are warranted to bring this technology forward towards further development, scaling-up and potential commercialization.

1.3.5 Acetoin

Acetoin is known to be a volatile compound, which is widely utilized in chemical synthesis, cigarettes, cleaning products, food, personal care products, plant growth, pest controls, wine, etc. (Cheynier et al ., 2010; Förster et al ., 2017; Xiao and Lu, 2014). Especially, acetoin has been largely applied as food flavoring (e.g., has an intense butter flavor) and fragrance manufacturing (Xiao and Lu, 2014). Moreover, acetoin is also highly promising, ranking in the top 30 for its potential applications as the bio-based building block precursors (Werpy and Petersen, 2004), which can embrace a green environment (e.g., petro-free economy). Due to these several industrial applications, in recent years, the production of acetoin became highly desirable due to a significantly large annual consumption across the globe (e.g., 2-4 mg per day per person, equal to several thousand tons per year worldwide) (Xiao and Lu, 2014).

Читать дальше
Тёмная тема
Сбросить

Интервал:

Закладка:

Сделать

Похожие книги на «Sustainable Solutions for Environmental Pollution»

Представляем Вашему вниманию похожие книги на «Sustainable Solutions for Environmental Pollution» списком для выбора. Мы отобрали схожую по названию и смыслу литературу в надежде предоставить читателям больше вариантов отыскать новые, интересные, ещё непрочитанные произведения.


Отзывы о книге «Sustainable Solutions for Environmental Pollution»

Обсуждение, отзывы о книге «Sustainable Solutions for Environmental Pollution» и просто собственные мнения читателей. Оставьте ваши комментарии, напишите, что Вы думаете о произведении, его смысле или главных героях. Укажите что конкретно понравилось, а что нет, и почему Вы так считаете.

x