The water audit mode of water environment and water ecology based on evaporation in industrial parks Open Access

With the world experiencing an increasingly serious water crisis, higher requirements are imposed on protecting water resources. United Nations-Water released the World Water Development Report 2020 (UN World Water Development Report 2020), which pointed out that global water consumption has been steadily increasing at a rate of about 1% per year. At the same time, several factors such as climate change have exacerbated the current water shortage. Industrial activities not only consume a large amount of freshwater but discharge wastewater, which causes serious environmental and social problems (Wang et al. 2019). According to the China Water Resources Bulletin in 2019 (China Water Resources Bulletin 2019), the industry accounts for 20.2% of total water consumption, and it is the second-largest sector just behind agriculture. In addition, the industry produces a large amount of harmful wastewater which needs treatment by special methods. Industrial parks (IPs), which are specialized industrial areas where there are high-intensity economic activities and high-strength resource consumption, also face the increasing problem of water resources protection (Kang & Xu 2012). Industrial parks consume large amounts of evaporation water, especially in heavy industries requiring high-temperature conditions, which may have an impact on the external environment of industrial parks. Water is not only a resource but also an important factor of the environment. A study has shown that water superabundance, water shortage, water quality, and water level can reflect the situation of the water environment, and meanwhile, water environment conditions directly affect natural and social ecology and will cause a series of water ecological problems (Aldous & Bach 2014). Therefore, the water consumption of the IP is closely related to the water environment and water ecology. The collaborative management of water environment and water ecology based on evaporation is a significant trend of industrial water management. It has important theoretical and practical significance in exploring the impact mechanism of IPs, establishing a monitoring feedback mechanism, and lowering the industrial water impact.

In general, IPs will evaluate the water management condition in terms of water loss, water leakage, cost, etc. by the method of water audit (Sayers et al. 2016). Water audit is an analytical tool that quantifies water flows and quality within a predefined boundary. At present, the water audit methodology is widely put into practice in the industry. It can determine where unexpected water losses are in the industry, and it has proven to be an effective tool for identifying water conservation strategies and promoting zero water discharge (Barrington & Ho 2014). However, it is hard for traditional water audit to meet the needs of the water environment and water ecology based on evaporation (3E), which require a multi-dimensional evaluation. Accordingly, a pressing need for a systematic approach that can provide accurate strategies and suggestions has arisen under such a management environment.

Currently, there are two main limitations of traditional water audit in meeting 3E requirements. (1) As a method that can measure the input and output of water in a certain period of time in any system, water audit has enough professional tools, including AWWA free water audit software, water balance models, water flow path diagrams, multi-criteria comprehensive evaluation methods, etc. (Nie et al. 2018; Manne et al. 2021). Water quality was audited for the first time by (Lipiwattanakarn et al. (2021). Thus, water audit mainly measures water quantity to calculate industrial water loss with the aid of existing tools, and might be rather narrow in scope. The audit of water quality and industrial impacts on water environment and water ecology deserves research. (2) Water audit in IPs reflects relatively one-sided economic effects. By this approach, researchers often find the key nodes of water saving and then propose water-saving measures, so the cost of industrial water can be reduced to a certain extent (Sayers et al. 2016). Thus, the economic effect is mainly reflected in the cost of water, without its internal profitability and external spillover. The traditional water audit method needs to be improved totally in scope and systematic application for 3E evaluation.

To help IPs make better evaluation for 3E management, previous research studies developed some quantitative evaluation methods. Related studies applied many approaches such as air and water quality indexes, water distribution networks, and analytic hierarchy process (AHP) etc. Lyu et al. (2021) employed life-cycle assessment theory and proposed a comprehensive evaluation of the environmental impacts of the in-use wastewater treatment system in chemical industrial parks. Flores Casamayor et al. (2021) combined fuzzy logic and analytic hierarchy process, where a decision tree contains environmental, social, economic, and hydrological aspects, to assess industrial impact on water sustainability. Sayal et al. (2016) selected variables of sickness, aversive expenditures, and medical costs, then used the probit model to evaluate water pollution impact on the health of the adjacent human community from an economic perspective. Nie et al. (2018) applied a multistage decision support framework in which four main criteria dimensions, namely water resources, social, economic, and environment are embedded into the industrial region for water security sustainability evaluation. Overall, the preceding methods that rely on indexes and their quantification can find intrinsic relationships between industrial water and performance. However, these existing methods are still limited in terms of practical IPs, and each approach has some shortcomings when applied to solving specific management issues of 3E.

Faced with narrowed water audit scope, insufficient spillover linkage, and incomplete comprehensive treatment, this paper takes the difficult control of evaporation as the perspective, and carries out comprehensive audit research from point to area. First, our paper clarifies the water use links of the water system in the IPs and the law of the water life-cycle in the system. Then we build a logical framework of the 3E water audit. According to this, we propose an index system reflecting 3E. Then, we apply it to a typical industrial park in Hebei Province, China.

This paper is organized as follows. In Methods, this paper proposes a water audit logic framework based on the characteristics of industrial park water use. We also build a systematic water audit index system. In Application and Results, we research a typical industrial park in China and give the water audit results. Finally, Discussion and Conclusions are provided.

In industrial parks, the multi-level and multi-node needs of production require a large amount of industrial water use. But in the water life-cycle of water intake, water use, water evaporation, and drainage, especially in the water intake and drainage stages (Sánchez-Torija et al. 2017), industrial production results in direct and indirect impacts on regional water resources and water ecology. Taking an iron and steel industrial park as an example, its industrial water system containing multi-levels and multi-nodes is shown in Figure 1, where circulating water flow, wastewater flow, and consumed flow between wastewater treatment plants and industrial systems are marked.

Through the analysis of water use in the iron and steel industrial park, its industrial water system is characterized by these three aspects:

• (1)

  Complicated water consumption process and large water consumption. First, the water consumption user is diverse. It is necessary to audit the main water users such as enterprises and residential buildings in the industrial park (Barrington et al. 2013). Secondly, there are various ways of industrial water consumption. After entering the water system, freshwater, reused water, and other waters are gradually consumed from high-temperature evaporation, pipe network leakage, carrying of products, and greening. Third, the multi-node and multi-level characteristics of the water system also increase the complexity of water consumption. The overall water system can be divided into three levels. The microlevel of the industrial water system refers to the specific water-use site (Levidow et al. 2016); the meso-level refers to a single system or a collection of subsystems (Levidow et al. 2016), such as business departments or internal production lines in the iron and steel industrial park; the macro-level refers to the entire park.

• (2)

  The spatial spillover effectiveness of water intake and water use on the regional water ecology. In the water life-cycle, water intake and water use are the necessary stages (Sánchez-Torija et al. 2017). In these two stages, industrial water systems increase groundwater and surface water, which are important water sources for maintaining water ecology. This will affect the amount and quality of ecological water supply (Aldous & Bach 2014), and aggravate the risk of water shortage in IPs.

• (3)

  The impact of drainage on the water environment. The discharge or leakage of wastewater in industrial parks forms toxic and non-biodegradable pollutants, which may cause water environment pollution (Liu et al. 2019). What is more, various industry companies have different structures of water consumption (Barrington et al. 2013). In turn, this leads to diverse types and concentrations of pollutants in the discharged wastewater, which makes the maintenance of the water environment more difficult.

Based on the concept of water audit proposed by Sturman et al. (2004), the water audit is defined as the impact assessment of the input and output water in the industrial water system on the internal and external environment in a certain period. The logical framework focuses on the specific goals of assessing the impact of industrial park water use on water resources, water environment and water ecology, and provides a general framework to provide a developable and revisable tool for future assessment (Weber et al. 2019). According to the periodic characteristics of the industrial water system, the logical framework of an industrial water audit is summarized according to the target and logical relationship, and the logical framework of the 3E water audit is established, as shown in Figure 2.

Inputs mean three water audit principles and three kinds of scope; the political, financial, and human resources of audit resources are needed to implement activities (Weber et al. 2019). Outputs mean construction and evaluation of the index system of the 3E water audit. Purposes mean performance improvement of efficiency, effect and economy (3e) (Chen et al. 2020). Goals mean cooperation to improve the impact of industry on water ecology and water environment based on evaporation.

To achieve the integrated management goals of water resources, water environment, and water ecology, the article proposes that evaluation indexes should follow the general principles of single-organization performance evaluation such as independence and operability, but also follow the principles of comprehensiveness, consistency, and dynamics.

• (1)

  Comprehensiveness (International Standard ISO 14046 2014; Chen et al. 2020). The actual use of water in industrial parks currently requires a comprehensive audit of the whole process, multiple levels, and multiple dimensions. Specifically, the water life-cycle includes the process of water intake, water supply, water use, and water drainage; industrial parks cover multiple levels of enterprises such as the water use units which are a micro-level; the behavior of water users in the industrial park will cause positive or negative influence and feedback of the dimension.

• (2)

  Consistency (International Standard ISO 14046 2014). At present, the water-saving mechanism of an industrial park is gradually improving, but there is still no targeted and effective verification of its effect. When selecting the indexes, the indexes are consistent with the audit scope, that is, the connotation of each index in the water audit index system is strictly consistent with the goals and scope. It is of great importance to analyse the characteristics of the evaluation object for accuracy. Therefore, this paper suggests the evaluation index is consistent with the main characteristics. The selected indexes should be representative, accurately reflect the characteristics of the industrial park, and reduce redundant indexes as much as possible.

• (3)

  Dynamics. Certain time-scale indexes as well as the commonness and difference between different industrial parks reflect the law of water use in industrial parks . Therefore, the selection of indexes should consider the dynamic characteristics of time and region. In addition, to be suitable for different audit cases, the index system allows the flexible addition of indexes in specific situations to optimize the index system.

The 3E water audit measures the 3E comprehensive impact of industrial water use and it lays stress on economy, efficiency, and effectiveness of industrial water referring to the 3e theory. The 3e theory (economy, efficiency, effectiveness) proposed by Professor Checkland based on soft system methodology from a system perspective has been regarded as the basic model for public policy evaluation (Chen et al. 2020). In the theory, economy reflects system cost, efficiency refers to the ratio between activity inputs and outputs, and effectiveness refers to the contribution of output to the goals. To measure the impact of industrial parks on evaporation, water environment, and water ecology with the 3e theory of economy, efficiency, and effectiveness, our study carries out the comprehensive evaluation index system of the 3E water audit that contains five dimensions, as shown in Figure 3, and fundamental factors including water balance and national standards lists.

As Figure 3 suggests, five index dimensions are selected in the comprehensive evaluation index system:

• (1)

  Legal aspect. Industries often become embroiled in legal battles over environmental issues (Sengupta 2018). Therefore, industrial water needs to comply with national laws and cross-sectoral regulations and norms to avoid legal costs and negative effects. This dimension emphasizes organization and standardization and reflects efficiency.

• (2)

  Eco-environmental aspect. The legal restriction on water use is aimed at protecting the environment and sustainable development (Sengupta 2018). The negative impacts of industrial water consumption on the ecological environment include eutrophication, pollution of water bodies and soil by toxic compounds, wastewater treatment efficiency, etc. (Romero et al. 2017; Cervantes-Jiménez et al. 2020). The ecological and environmental aspect emphasizes natural impact, which reflects effect.

• (3)

  Economic aspect. The water use activities of industrial park enterprises are commercial activities that consume costs and generate profits. While meeting environmental and legal requirements, they must also maximize profits (Sengupta 2018). This dimension emphasizes cost and value, which reflects the economy.

• (4)

  Social aspect. Generally speaking, social performances include employee welfare, working conditions, the number of accidents, and other positive or negative indexes (Dobre et al. 2015). Water resource activities in industrial parks involve many stakeholders (Sengupta 2018), such as the government, communities, and enterprises. This dimension emphasizes social satisfaction and public opinion, which reflects the effect.

• (5)

  Technological aspect. Science and technology have great potential in business, for reducing production costs, developing new products, improving management efficiency, and so on . Industrial parks, especially in different units and departments of enterprises, can improve water use efficiency, reduce water loss, and predict various kinds of water production, such as the amount of wastewater (Pham et al. 2016). This dimension reflects the effectiveness.

In accordance with the aforementioned characters, the indexes were established from five aspects consisting of the legal aspect, ecological and environmental aspect, economic aspect, social aspect, and technological aspect. According to the water full-cycle of the industrial park and water use characteristics of the iron and steel industry, primary indexes and secondary indexes were selected from related references and national standards (Cleaner Production Standard Iron & Steel Industry 2006; Water Saving Enterprises – Iron & Steel Industry 2011; Technical Guides for Audit of Water Use 2012; Standard for National Demonstration Eco-industrial Parks 2015). As a result, 11 primary indexes and 25 secondary indexes are obtained for the 3E water audit. This index system of the 3E water audit mainly includes predominant indexes such as quantity of water use per ton of steel and pipe leakage percentage, and is as shown in Table 1.

It is worth mentioning that every index can reflect industrial impact on the 3E and 3e. For example, compliance with a water collection permit belonging to the legal aspect evaluates the relationship between water intake political resource and implementation. It measures water resource efficiency, and so for the other indexes. The audit meaning of the 25 water audit indexes is listed in Table 1.

Evaluating the index system of the 3E water audit in industrial parks involves three steps: calculating the value of each index; determining the weight of each index; determining the comprehensive value (Kang & Xu 2012). Despite being the key content of water audit implementation, the calculation step must deal with the complex nature of indexes which make them hard to qualify. Therefore, this paper focuses on innovating methods of calculation and quantification. Three index quantification methods are proposed: the measurement-scale method, the content satisfaction ratio method, and the index formula method.

• (1)

  The measurement-scale method. Where qualitative index values refer to classes or categories (e.g. ‘sufficient/good/ high’), numerical values are assigned integrally between 1 and 5 (Maiolo & Pantusa 2019). For example, the impact index of the influence degree of sewage discharge on the water function zone is given 1 to 5 points according to the classification of great impact, large impact, general impact, small impact, and no impact respectively.

• (2)

  The content-meeting rate method. This method is suitable for a qualitative index which cannot be evaluated by the scale. It refers to the national or industry standard of the index to determine the percentage score of the index. Take the index of the production process and equipment for an example. According to Water Saving Enterprises – Iron & Steel Industry (2011), this index should meet the two requirements of the index content that ‘water-saving technology transformation is carried out and new water-saving processing, new technology, and new equipment are well managed and operate normally’. Then, according to the quantity of the conditions met, the score value of the calculation index is n/2 × 100%, where n suggests the number of the index of production process and equipment meeting requirements. Because the evaluation criteria directly influences the evaluation results, it is of significance to determine unique evaluation criteria for each index (Liu et al. 2019).

• (3)

  The index formula method. This method gives the formula to calculate the index value according to the index definition. For example, the total water consumption index for 10,000 yuan of industrial added value is calculated as total water consumption (cubic metres) divided by industrial added value (10,000 yuan). The statistics of the nature and quantification methods of all the water audit indexes are shown in Table 2.

Because the evaluation criteria directly influence the evaluation results, it is important to determine unique evaluation criteria for each indicator (Liu et al. 2019). Regarding the indexes measuring quantity, the criteria were determined by referring to the national legal standards, industry standards, local standards, field investigations, literature analysis, and expert opinions (Di Iaconi et al. 2017). After the evaluation standardization, each index is scored in the percentage system. Then the weight of each indicator and the comprehensive value are determined.

IPs in China have developed rapidly since 1979 and there are more than 15,000 industrial parks throughout the country. Chengde Iron and Steel Industrial Park (Chengsteel IP) is located in Chengde City, Hebei Province. This large iron and steel complex is one of the largest vanadium product manufacturers in China and takes priority in the iron and steel industry. Recently, the rapid development of the iron and steel industry appears to have put more pressure on natural resources. The water management in Chengsteel IP meets problems such as high water-consumption or inaccurate forecasting of water quantity. Hence, in this case study, the water life-cycle in IPs will be examined by the 3E water audit methods.

The acquisition of data for the case study was done through an expert interview and questionnaire-survey expressly developed for the study. The expert interview on the 25 water audit indexes was conducted with IP administrators. The inquiries contained 11 questions, grouped into three blocks: essential information such as population, area, annual value and steel output, etc; water volume of freshwater, reuse water, reclaimed water and leaking water; and organization and related water-saving measures of the whole life-cycle of water use. Then the questionnaire survey on two social indexes was conducted through residents by Likert scale. All interviews and questionnaires were conducted on the ground by researchers. The research processing flow is shown in Figure 4.

Since this application is a single scheme evaluation problem, this paper refers to lots of international standard documents and classifies every index into three grades. This paper also uses an expert grading method to get weights that pass the consistency test. Finally, the 3E water audit result in the Chengsteel IP in 2019 is shown in Table 3.

The 3E audit score of the Chengsteel IP was 89.91, which was less than 95 but more than 60, suggesting comprehensive performance is good (Technical Guides for Audit of Water Use 2012). The advantages of water resources management are mainly reflected in 17 level III indexes. Specifically, six compliance indexes are level III. The park meets the compliance requirements of water intake, water use and drainage, and the water management organization has a relatively perfect division of labor and assessment mechanism. Four eco-environmental indexes are level III. The standard rate of wastewater treatment in the park itself is 100%, and the drainage from the park to the outside is zero, greatly reducing the impact on the environment. Four economic indexes are also level III. In the production process of the park, there is less water consumption per ton of steel. The freshwater consumption per 10,000 yuan output value is better in the same industry in the same period. Converted to standard units of US dollars (USD), it took 58.21 m³ of freshwater to produce 10,000 USD output value in 2019. The value 58.21 is significantly lower than the 706.06 m³ of USA average level of industrial water use and the 241.41 m³ of China. It suggests Chengsteel IP's leading water-using level. The overall reuse rate of industrial water in the IP reaches 94.4%, and the utilization rate of circulating water is high. One social level-III index indicates that it fully ensures people's water services. Two technical indexes are also level III. The enterprises in the park have relatively perfect equipment and production technology. In addition, the leakage rate of the pipe network in the plant area is lower than the national standard, which is conducive to water saving.

However, the other eight indexes performed poorly. The rate of reaching the standard of water quality of the water function zone is 16.7% and reaches level I. Quantity per-capita water use for the industrial park is 298.04 m³/person, more than 140 m³/person, which means every permanent resident consumes 298.04 m³ domestic freshwater and is a poor performance. Water-use strength per square metre is 16.66 m³/m². It is much higher than the average level of Chengde City and Hebei Province. In social terms water safety is level II. There were few water accidents in 2019. Water-saving technical monopoly proportion is level II and ranks in the middle of the steel industry. At last, the ratio of coverage of industrial water-consumption measurement failed to reach 100% and the measurement instruments in Chengsteel IP are not equipped in time or in place.

To certify the reliability of the index values and final scores generated by the proposed method, the paper tests the results from two aspects: changing the examining year to 2018; and replacing the eigenvalue method with the geometric average method to get weight. The results indicate that scores were substantially consistent with the above. As such, the 3E audit proposed in this study has a good performance in evaluating 3E impact to some extent.

By examining the life-cycle impacts of evaporation in the typical Chengsteel IP, we revealed three main findings generated in the process. First, much attention should be paid to the water resources economy, because the production and domestic water consumption in the park was relatively high and the spillover effect was marked. This is very common in heavy industrial parks (Lyu et al. 2021). For the companies, it is better to improve the evaporation water condensation technology and wastewater reuse technology in the park (Manne et al. 2021), and it is better for residents to take water-saving measures, such as providing water-saving appliances in the living area to save water for greening and offices. Second, it is advisable to ensure the efficiency of pipe networks in IPs. It is suggested to increase the research and development investment in water-saving patented technology, explore new water supply modes, give priority to replacing the water supply pipe network of energy business departments and others with large water consumption, and carry out regular maintenance of the whole pipe network (Wrage 2021). Finally, attention should be paid to the identification of water risk points to ensure water safety. It is still recommended to strengthen the accident emergency plan.

This audit method is a proper and actionable attempt to evaluate influence on the water environment and water ecology based on evaporation in IPs. Referring to the improved model proposed by Weber et al. (2019), this paper builds the general logical framework that contains inputs, outputs, purposes, and goals to clarify the mindset logic of 3E. What is more, this paper pays more attention to the part of outputs and proposes the comprehensive evaluation index system of the 3E water audit innovatively. The 3E water audit of the logical framework and the comprehensive evaluation index system in IPs enriches research between regional water quality and water ecology (Lipiwattanakarn et al. 2021) and also helps to strengthen industrial water management. The logical framework of the 3E audit is proven to be superior to the few similar frameworks. Compared with the multistage decision support framework for water security sustainability evaluation proposed by Nie et al. (2018), this paper stresses top-level design and points out feedback cycles in four parts, which is more focused. With regard to audit meaning, the comprehensive evaluation index system in this paper not only judges water-saving strategies by index values (Romero et al. 2017) but also reflects industrial parks' impact on water resources, water environment and water ecology as well as the effectiveness, efficiency and economy of the 3e theory. It is convenient for managers of industrial parks or national government to judge the impact from the indexes, which has the advantages of simplicity and sustainability.

Following the internal laws of industrial water use and its impact on the outside, our study puts forward a new audit method called the 3E audit mode. Using the logical framework approach, our study puts forward the 3E water audit logical framework for industrial water. Then the water audit index system and its quantitative method are established. To sum up, the study realizes the 3E comprehensive audit based on the quantification of 25 indexes in five dimensions with the 3E goals, which is theoretically complete. The main contributions of this study include the following.

(1) The new 3E water audit method not only expands the connotation of economics but adds technology and social dimensions. It is more comprehensive for IP managers to evaluate external impacts than the traditional audit method. (2) This paper takes evaporation as the perspective, and reveals the linkage among evaporation water, water environment and water ecology by 25 indexes. (3) We have selected a demonstration case to confirm the reliability of the logical framework and index system. This application has realized refinement of the monitoring of water balance and the fine evaluation of water audit, and the accurate strategies and suggestions provided have been adopted by the park and used as the basis for subsequent continuous improvement.

However, there are still some limitations in this study. Since the comprehensive evaluation index system conforms to the actual situation in iron and steel industrial parks, indicators need to be further adjusted according to the principle of the logical framework when auditing other types of industrial parks. Considering that the 3E audit was applied to the single scheme evaluation of an iron and steel industrial park, the index weights of this paper are relatively limited and subjective. It is also necessary to further test the effectiveness by using the entropy weight method and TOPSIS method in the case of multiple schemes.

Data cannot be made publicly available; readers should contact the corresponding author for details.

The authors declare there is no conflict.