Efficacy of neutral electrolyzed water (NEW) for reducing microbial contamination on minimally-processed vegetables

Consumption of minimally-processed, or fresh-cut, fruit and vegetables has rapidly increased in recent years, but there have also been several reported outbreaks associated with the consumption of these products. Sodium hypochlorite is currently the most widespread disinfectant used by fresh-cut industries. Neutral electrolyzed water (NEW) is a novel disinfection system that could represent an alternative to sodium hypochlorite. The aim of the study was to determine whether NEW could replace sodium hypochlorite in the fresh-cut produce industry. The effects of NEW, applied in different concentrations, at different treatment temperatures and for different times, in the reduction of the foodborne pathogens Salmonella, Listeria monocytogenes and Escherichia coli O157:H7 and against the spoilage bacterium Erwinia carotovora were tested in lettuce. Lettuce was artificially inoculated by dipping it in a suspension of the studied pathogens at 10(8), 10(7) or 10(5) cfu ml(-1), depending on the assay. The NEW treatment was always compared with washing with deionized water and with a standard hypochlorite treatment. The effect of inoculum size was also studied. Finally, the effect of NEW on the indigenous microbiota of different packaged fresh-cut products was also determined. The bactericidal activity of diluted NEW (containing approximately 50 ppm of free chlorine, pH 8.60) against E. coli O157:H7, Salmonella, L. innocua and E. carotovora on lettuce was similar to that of chlorinated water (120 ppm of free chlorine) with reductions of 1-2 log units. There were generally no significant differences when treating lettuce with NEW for 1 and 3 min. Neither inoculation dose (10(7) or 10(5) cfu ml(-1)) influenced the bacterial reduction achieved. Treating fresh-cut lettuce, carrot, endive, corn salad and 'Four seasons' salad with NEW 1:5 (containing about 50 ppm of free chlorine) was equally effective as applying chlorinated water at 120 ppm. Microbial reduction depended on the vegetable tested: NEW and sodium hypochlorite treatments were more effective on carrot and endive than on iceberg lettuce, 'Four seasons' salad and corn salad. The reductions of indigenous microbiota were smaller than those obtained with the artificially inoculated bacteria tested (0.5-1.2 log reduction). NEW seems to be a promising disinfection method as it would allow to reduce the amount of free chlorine used for the disinfection of fresh-cut produce by the food industry, as the same microbial reduction as sodium hypochlorite is obtained. This would constitute a safer, 'in situ', and easier to handle way of ensuring food safety.     

可食性活性涂膜在鲜切果蔬保鲜中的应用

可食性涂膜是一种由天然可食性材料制成的选择透过性薄膜,具有调节果蔬内部气体交换、减少水分损失、降低腐烂率及延长货架期的特性,在果蔬包装及保鲜领域中已引起广泛关注。鲜切果蔬具有新鲜、方便、快捷等特点,已在全球范围内广泛供应餐饮业及零售业。可食性涂膜作为多种食品添加剂的载体常应用于生鲜产品中,且将活性添加剂与可食性涂膜结合可以延长鲜切果蔬的货架期,提高果蔬品质,减少果蔬表面致腐及致病菌增长的风险。可食性活性涂膜将作为一种绿色、安全、营养的保鲜技术,并将应用于鲜切果蔬保鲜领域的研究。本文综述了可食性涂膜的分类及其添加的抗菌剂、抗氧化剂、塑形剂、营养素等活性成分在鲜切果蔬保鲜中的应用,旨在开发用于鲜切果蔬保鲜的功能性可食性涂膜。     

Use of neutral electrolysed water (EW) for quality maintenance and shelf-life extension of minimally processed lettuce

Experiments were conducted to determine the effectiveness of different treatments based on the use of neutral electrolysed water (EW) on fresh-cut lettuce. EW was diluted to obtain different free chlorine concentrations (120, 60 and 12 ppm) and to compare with standard washing treatment of 120 ppm chlorine solution. Shelf-life quality and safety markers were studied at the beginning and at the end of the 7-day-storage at 4 °C. The use of EW decreased the respiration rate of the samples which might be related with the observed reduction in microbial spoilage. The use of EW also increased the activity of a browning-related enzyme (polyphenoloxydase) although sensory results showed all samples as acceptable at the end of the 7 day-storage. Perhaps longer storage time might increase the risk to browning development in the samples treated with EW. The highest EW concentration (120 ppm free chlorine) was the most effective treatment in reducing sample microbial load; however this treatment also affected the final produce with effects such as loss of turgor, plasmolysis and a reduction in mineral content.Results suggest an intermediate EW concentration with 60 ppm free chlorine could be an alternative to 120 ppm chlorine (from sodium hypochlorite) for sanitizing fresh-cut vegetables, reducing to half the amount of chlorine used and maintaining the antimicrobial effectiveness and without differences affecting the quality. However further studies will be necessary in order to observe the effect of the oxidising capacity of EW on other quality and safety markers as pathogens and nutritional content.Industrial relevanceChlorine solutions have been widely used to sanitise fruit and vegetables in the fresh-cut industry. However, the association of chlorine with the possible formation of carcinogenic chlorinated compounds in water has called into question the use of chlorine in food processing. The efficacy in controlling the microbial load and browning of samples treated with electrolysed water shows it as a promising decontaminant agent for fresh-cut lettuce. Due to the high oxidising potential of the EW quality requirements must be balanced to obtain the optimal treatment conditions keeping satisfying safety levels. The use of EW-60 showed similar safety and quality (browning) results as the use of chlorine or double EW concentration (EW-120). However the treatment EW-120 affected negatively the textural properties. The study suggests the use of EW-60 as an alternative to sodium hypochlorite solution with 120 ppm available chlorine, obtaining similar safety and quality results and reducing the amount of chlorine needed. Further investigations in the effect of EW on lettuce, such as those on pathogens or nutritional markers (e.g. carotenoids and vitamin C) are recommended in order to explore this alternative that might reduce the increasingly concerning use of chlorine to decontaminate this type of product.     

大气压冷等离子体在鲜切果蔬保鲜中的应用研究进展

鲜切果蔬因具有新鲜方便、无添加剂和营养价值高等优点而广受消费者喜爱,但是鲜切果蔬在加工和贮藏过程中极易受微生物污染,导致食品品质劣变并缩短货架期。大气压冷等离子体（Atmospheric cold plasma,ACP）是一种新型非热加工技术,广泛应用于食品及生物医药领域。本文综述了ACP对鲜切果蔬表面微生物的灭活效果以及对鲜切果蔬中酶活的作用,同时探讨了ACP处理对鲜切果蔬品质的影响,旨在为ACP在鲜切果蔬保鲜中的应用提供参考。     

光动力抗菌技术在鲜切菜加工除菌过程中的应用研究进展

微生物灭活作为鲜切菜加工过程中关键的步骤之一,关系着鲜切菜的保质期与食品安全问题。因此,研究和利用各种除菌技术以延长鲜切菜保鲜期、保证食品安全与质量十分重要。光动力抗菌技术(photodynamic antimicrobialtechnology,PDAT)是一种新兴的食品非热除菌技术手段,利用光生的活性氧自由基(reactive oxygenspecies,ROS)攻击微生物细胞的多个靶点,不易产生耐药性,在鲜切菜领域展现出了巨大的应用前景,为当前研究的前沿热点。考虑到鲜切菜本身具有的生理活性成分与光敏剂之间的相互作用,相比离体实验,PDAT在鲜切菜中的应用效果有限,应将其视为额外的除菌工具,而不是其他传统除菌技术的替代品。本文以鲜切菜的食品安全为出发点,综述了PDAT的原理、方法优势及劣势,鲜切菜的代谢生理变化与PDAT在鲜切菜领域上的应用研究进展与未来发展方向,以期为促进净菜产业的食品安全和PDAT的发展提供依据。     

EFFECT OF CHLORINE TREATMENT ON CUT WATER CRESS AND ONION

Chlorine treatment was evaluated for cut vegetables to reduce microbial populations and improve keeping quality. Water cress and onion were selected because they are representative vegetables having high potential for processing into cut prepared products. Cut water cress had a high initial microbial contamintion of 10^7.5 cfu/g, while cut onion had only 10^1.7 cfu/g. The cut produce was treated by soaking in chlorine solutions of different concentrations at 25C for 1 min. Treatment with ≤100 ppm chlorine effectively reduced the microbial load of the produce without significant quality losses. High concentrations of chlorine resulted in greater microbial proliferation after 7 days, ascorbic acid destruction and significant color change in stored cut vegetables. The effectiveness of chlorine treatment was limited to short-term storage of precut vegetables, and did not provide extended shelf-life.     

热处理对鲜切果蔬品质影响的研究进展

鲜切果蔬方便、营养的特性越来越受到加工者和消费者的重视和青睐,然而短暂的货架期已成为限制鲜切果蔬发展的瓶颈难题。为了在保证其食用安全性的前提下,延长鲜切果蔬的货架期,有必要寻找或开发更为环保和安全的鲜切果蔬加工方法,来取代氯水清洗或其他化学试剂在果蔬去皮、切块、清洗等工序中的使用。热处理是一种传统的物理保鲜方法,而将热处理技术应用在鲜切果蔬贮藏保鲜是近年来的研究热点。为此,本文概括了热处理和热处理与其他技术相结合对鲜切果蔬感官品质、营养品质和安全品质的影响,同时归纳了热处理对鲜切果蔬保鲜的机理。以期为热处理应用于鲜切果蔬的贮藏保鲜和提高鲜切果蔬的食用安全提供参考。     

非热加工在鲜切果蔬安全品质控制中的应用进展

鲜切果蔬由于其食用方便、营养丰富、清洁卫生等特点,近年来倍受人们关注。但由于鲜切果蔬在实际生产中极易发生微生物污染、营养成分和食用品质降低等不良变化,严重阻碍了鲜切果蔬加工业的进一步发展。非热加工技术是目前鲜切果蔬加工研究的热点,基于此探讨臭氧、电解水、辐照、紫外、脉冲物理场、超声波、高静压及高压二氧化碳等非热加工技术,在鲜切果蔬安全性与品质控制中的应用研究进展。     

Evaluation of the use of decontamination agents during fresh-cut leek processing and quantification of their effect on its total quality by means of a multidisciplinary approach

In this study the impact of different decontamination agents (water, peroxyacetic acid, sodium hypochlorite, neutral electrolyzed oxidizing water and gaseous chlorine dioxide) on the microbial and sensory quality as well as the nutrient content of minimally processed leek was investigated. Washing with 250 mg/L peroxyacetic acid and contact with 1.59 mg/L chlorine dioxide gas reduced the native microflora with 1.52 and 1.48 log cfu/g respectively whereas the other treatments did not induce a reduction that was significantly higher than the one achieved after washing with water. None of the treatments had a significant effect on the sensory quality of the raw fresh-cut leek, whereas a treatment with 200 mg/L sodium hypochlorite or with 250 mg/L peroxyacetic acid changed the sensory quality of cooked leek significantly when compared with water washing. Apart from the effect of leaching of nutrients into the wash water, the supplementary effect on nutrient content caused by adding a decontamination agent was limited with the exception of some isolated cases such as the significant losses of vitamin C (23%), tocopherols (11–18%) and violaxanthin (66%) after a treatment with respectively chlorine dioxide, 250 mg/L peroxyacetic acid and electrolyzed oxidizing water.Industrial relevanceVegetables like leek are highly contaminated with micro-organisms due to their contact with soil, water and other debris as a result of preharvest as well as postharvest conditions. Moreover, the sales of fresh-cut vegetables such as fresh-cut leek showed a tremendous increase over the last decade. Usually these products have a limited shelf-life due to microbial, sensorial and chemical alterations. The fresh-cut produce industry is continuously looking for treatments able to replace the traditionally used sodium hypochlorite which is associated with the formation of harmful disinfection by-products. In this study more innovative treatments like neutral electrolyzed oxidizing water, peroxyacetic acid and gaseous chlorine dioxide were studied for their effect on the microbial, sensory and nutritional quality of fresh-cut leek.     

Efficacy of sanitizers to inactivate Escherichia coli O157:H7 on fresh-cut carrot shreds under simulated process water conditions

Chlorine is widely used as a sanitizer to maintain the microbial quality and safety of fresh-cut produce; however, chlorine treatment lacks efficacy on pathogen reduction, especially when the fresh-cut processing water contains heavy organic loads. A more efficacious sanitizer that can tolerate the commercial processing conditions is needed to maintain microbial safety of fresh-cut produce. This study evaluated the efficacy of Escherichia coli O157:H7 reduction on fresh-cut carrots using new and traditional sanitizers with tap water and fresh-cut processing water scenarios. Fresh-cut carrot shreds inoculated with E. coli O157:H7 were washed in sanitizer solutions including 200 ppm chlorine, citric acid-based sanitizer (Pro-San), 80 ppm peroxyacetic acid-based sanitizer (Tsunami 100), and 1,000 ppm acidified sodium chlorite (SANOVA) prepared in fresh tap water or simulated processing water with a chemical oxygen demand level of approximately 3,500 mg/liter. Samples were packaged and stored at 5 degrees C. Microbial analyses performed at days 0, 7, and 14 indicate that the organic load in the process water significantly affected the efficacy of chlorine on pathogen removal and was especially evident on samples tested during storage. Acidified sodium chlorite provided a strong pathogen reduction even under process water conditions with up to a 5.25-log reduction when compared with the no-wash control. E. coli O157:H7 was not recovered on acidified sodium chlorite-treated samples during the entire 14 days of storage, even following an enrichment step. These results suggest that acidified sodium chlorite holds considerable promise as an alternative sanitizer of fresh-cut produce.     

Factors affecting quality and safety of fresh-cut produce

The quality of fresh-cut fruit and vegetable products includes a combination of attributes, such as appearance, texture, and flavor, as well as nutritional and safety aspects that determine their value to the consumer. Nutritionally, fruit and vegetables represent a good source of vitamins, minerals, and dietary fiber, and fresh-cut produce satisfies consumer demand for freshly prepared, convenient, healthy food. However, fresh-cut produce deteriorates faster than corresponding intact produce, as a result of damage caused by minimal processing, which accelerates many physiological changes that lead to a reduction in produce quality and shelf-life. The symptoms of produce deterioration include discoloration, increased oxidative browning at cut surfaces, flaccidity as a result of loss of water, and decreased nutritional value. Damaged plant tissues also represent a better substrate for growth of microorganisms, including spoilage microorganisms and foodborne pathogens. The risk of pathogen contamination and growth is one of the main safety concerns associated with fresh-cut produce, as highlighted by the increasing number of produce-linked foodborne outbreaks in recent years. The pathogens of major concern in fresh-cut produce are Listeria monocytogenes, pathogenic Escherichia coli mainly O157:H7, and Salmonella spp. This article describes the quality of fresh-cut produce, factors affecting quality, and various techniques for evaluating quality. In addition, the microbiological safety of fresh-cut produce and factors affecting pathogen survival and growth on fresh-cut produce are discussed in detail.     

Development of rapid hygrothermal pasteurization using saturated water vapor

We developed a novel rapid hygrothermal pasteurization (RHP) method using saturated water vapor with a dew point of 100 °C. In the present study, the effects of RHP on microbiological quality and quality attributes such as color changes, firmness and ascorbic acid content on many fresh-cut fruits and vegetables (cabbage, cucumber, carrot, cherry tomato, bell pepper, strawberry, pineapple and melon) were investigated. The RHP was performed within a second by free-falling samples through a cylindrical processing chamber filled with steam. The RHP resulted in a 0.7–2.0 log order reduction in the numbers of naturally inoculated mesophilic bacteria. Furthermore, the RHP induced no significant changes in color and firmness of samples, except on the leafy vegetable, cabbage. Ascorbic acid was also retained approximately 80% and above. These results indicate that the RHP is a clean and effective method for decontaminating mesophilic bacteria on fresh fruits and vegetables with minimal changes in quality.Industrial relevanceIn fresh-cut industry, an effective and risk-free decontamination technology is required for use in place of a conventional method, washing by chlorine that can produce carcinogenic chlorinated by-products. In this study, the rapid hygrothermal pasteurization (RHP) method using saturated water vapor was invented and their ability for applying minimal processing was evaluated. The results showed that RHP, without using chemicals, can reduce microorganism load and preserve quality attributes in many kinds of fresh-cut fruits and vegetables. Therefore, RHP could be used as a novel method, which can be generally applicable to fresh-cut fruits and vegetables in the food industry.     

Comprehensive review of water management and wastewater treatment in food processing industries in the framework of water-food-environment nexus

Food processing is among the greatest water-consuming industries with a significant role in the implementation of sustainable development goals. Water-consuming industries such as food processing have become a threat to limited freshwater resources, and numerous attempts are being carried out in order to develop and apply novel approaches for water management in these industries. Studies have shown the positive impact of the new methods of process integration (e.g., water pinch, mathematical optimization, etc.) in maximizing water reuse and recycle. Applying these methods in food processing industries not only significantly supported water consumption minimization but also contributed to environmental protection by reducing wastewater generation. The methods can also increase the productivity of these industries and direct them to sustainable production. This interconnection led to a new subcategory in nexus studies known as water-food-environment nexus. The nexus assures sustainable food production with minimum freshwater consumption and minimizes the environmental destructions caused by untreated wastewater discharge. The aim of this study was to provide a thorough review of water-food-environment nexus application in food processing industries and explore the nexus from different aspects. The current study explored the process of food industries in different sectors regarding water consumption and wastewater generation, both qualitatively and quantitatively. The most recent wastewater treatment methods carried out in different food processing sectors were also reviewed. This review provided a comprehensive literature for choosing the optimum scenario of water and wastewater management in food processing industries.     

二氧化氯对肉制品保鲜的研究

二氧化氯是一种有效的食品保鲜剂 ,目前在水处理、食品加工、保鲜等方面已得到广泛应用。试验研究了不同浓度二氧化氯对酱鸭的保鲜效果及其对酱鸭品质的影响。结果表明 ,酱鸭经浓度为 10 0～ 2 0 0mg/kg的二氧化氯溶液处理 2min后 ,常温下贮存 2 6～ 3 0d仍可保持较好的品质。     

Insight into the prevalence and distribution of microbial contamination to evaluate water management in the fresh produce processing industry

This study provided insight into the degree of microbial contamination in the processing chain of prepacked (bagged) lettuce in two Belgian fresh-cut produce processing companies. The pathogens Salmonella and Listeria monocytogenes were not detected. Total psychrotrophic aerobic bacterial counts (TPACs) in water samples, fresh produce, and environmental samples suggested that the TPAC is not a good indicator of overall quality and best manufacturing practices during production and processing. Because of the high TPACs in the harvested lettuce crops, the process water becomes quickly contaminated, and subsequent TPACs do not change much throughout the production process of a batch. The hygiene indicator Escherichia coli was used to assess the water management practices in these two companies in relation to food safety. Practices such as insufficient cleaning and disinfection of washing baths, irregular refilling of the produce wash baths with water of good microbial quality, and the use of high product/water ratios resulted in a rapid increase in E. coli in the processing water, with potential transfer to the end product (fresh-cut lettuce). The washing step in the production of fresh-cut lettuce was identified as a potential pathway for dispersion of microorganisms and introduction of E. coli to the end product via cross-contamination. An intervention step to reduce microbial contamination is needed, particularly when no sanitizers are used as is the case in some European Union countries. Thus, from a food safety point of view proper water management (and its validation) is a critical point in the fresh-cut produce processing industry.     

Quality attributes of shredded carrot (Daucus carota L. cv. Nantes) as affected by alternative decontamination processes to chlorine

The effects of alternative decontamination processes to chlorine: ozonated-water (1 ppm/5 min), hot water (100 °C/45 s) and ultrasonication (45 kHz/1 min), applied pre- or post-cut in the technological diagram of minimal processing of carrots were tested. Ultrasonication in chlorinated-water and thermo-ultrasonication as combined processes applied just in pre-cut carrot were also tested. The initial microbial load reduction, soluble solids content, pH and sensorial attributes of shredded carrot just after processing were evaluated. Decontamination processes applied on pre-cut carrot provided maintenance of fresh-like sensorial quality, regardless the type of treatment, due to diminished leaching phenomena which is critical for shredded carrot. Chlorination, ozonization and ultrasonication achieved ca. 1 Log₁₀ reduction of initial microbial load. No additional decontamination effect in combined processes was observed. The use of heat in pre-cut carrot proved to be the most efficient process regarding microbial reduction (3 Log₁₀ units) providing, as well, an acceptable fresh-like quality product.Industrial relevanceThe major constraint for marketability of minimally processed shredded carrot is its limited shelf-life due to rapid microbial growth and colour loss (decrease of orange intensity and/or whitening of the shreds). These questions arise from the practical experience of a fresh-cut industry directly involved in the R&D research project which supported this study. Chlorine solutions have been widely used to sanitize fruit and vegetables in the fresh-cut industry. However, reduced microbiological efficiency allied to the eventual formation of carcinogenic chlorinated compounds pointed out the need for alternative methodologies. The present work aimed the evaluation of clean alternative decontamination processes applied both to pre- and post-cut carrot for the production of shredded carrot, operating under conditions of industrial practice at pilot-plant scale.     

食品加工用水微生物检测的重要性

食品加工业是用水型工业之一,水质的优劣对食品安全至关重要,对加工用水进行安全卫生控制是生产过程控制的重要环节。微生物污染是食品加工用水最主要的安全隐患之一,我国食品加工用水微生物污染风险高、概率大,每年因食品加工用水微生物污染导致的产品质量问题不在少数,给企业造成了巨大的经济损失。食品加工企业对加工用水的质量控制必不可少,尤其是加工用水的微生物检测能力会影响最终产品的安全性。企业应打破只重视原料、过程产品和最终产品微生物检测的老思路,注意监控加工用水的微生物污染情况。参加水质微生物能力验证能够加强企业实验室对生产加工用水的自我检测能力,确保检测结果的准确性和认可性,对提高产品质量和品质有促进作用。     

Use of lysozyme as an indicator of protein cross-contact in fresh-cut vegetables via wash waters

To evaluate risks linked to cross-contact of allergenic proteins in food production sites via carry-over, it is necessary to gain more insight in the behavior of proteins during processing. A typical case example of cross-contact is related to the re-use of wash water in the fresh-cut vegetable processing industry. In this study, the carry-over of allergenic proteins via wash water was quantified by applying an allergen-indicator, lysozyme. The adsorption of the allergen to the fresh-cut vegetables could be characterized by a Langmuir adsorption isotherm. From the adsorption characteristics, it was observed that the carry-over was significantly stronger on carrots compared to lettuce and leek. This was moreover observed from the mass balance which illustrated that the total amount of lysozyme transferred from the wash water to the fresh-cut vegetables was in average 77.4, 25.1 and 22.2% for respectively carrots, lettuce and leek. From a deterministic risk assessment, it could be concluded that allergenic proteins can be transferred via wash water to fresh-cut vegetables in the next production batch in such quantities that they pose a risk towards allergic consumers. The proposed methodology enables the food industry to validate designed preventive measures in the framework of their allergen management.     

Role of biological control agents and physical treatments in maintaining the quality of fresh and minimally-processed fruit and vegetables

Abstract

Fruit and vegetables are an important part of human diets and provide multiple health benefits. However, due to the short shelf-life of fresh and minimally-processed fruit and vegetables, significant losses occur throughout the food distribution chain. Shelf-life extension requires preserving both the quality and safety of food products. The quality of fruit and vegetables, either fresh or fresh-cut, depends on many factors and can be determined by analytical or sensory evaluation methods. Among the various technologies used to maintain the quality and increase shelf-life of fresh and minimally-processed fruit and vegetables, biological control is a promising approach. Biological control refers to postharvest control of pathogens using microbial cultures. With respect to application of biological control for increasing the shelf-life of food, the term biopreservation is favored, although the approach is identical. The methods for screening and development of biocontrol agents differ greatly according to their intended application, but the efficacy of all current approaches following scale-up to commercial conditions is recognized as insufficient. The combination of biological and physical methods to maintain quality has the potential to overcome the limitations of current approaches. This review compares biocontrol and biopreservation approaches, alone and in combination with physical methods. The recent increase in the use of meta-omics approaches and other innovative technologies, has led to the emergence of new strategies to increase the shelf-life of fruit and vegetables, which are also discussed herein.     

INDUSTRIAL WASTEWATER CONTROL1

The reduction or elimination of industrial wastes at their in-plant sources is a more economical and more effective practice than their treatment at the plant outfall. Examples described, all selected from the food industries, are the hot gas blanching of vegetables, the dry peeling of fruits and vegetables by application of caustic, the recovery of useful by-products from whey, the reuse of poultry processing wastewaters and reduced water usage in the poultry industry, and material recovery from brewery, citrus, and fishery operations. All of these result in a smaller quantity of wastewater and pollutants going to treatment or discharge. End-of-pipe treatment is frequently required, even after all practical in-plant clean-up. Discharge into municipal sewers is discussed, as are the basic operations and processes available for pretreatment as well as for final treatment prior to discharge to a waterway. The author's premise is a plea for sharing of knowledge among different industries.