Establishment of Effluent Standards for Industrial Wastewaters in Korea: Current Issues and Suggestions for Future Plan

ABSTRACT Industrial wastewaters have been strongly controlled by effluent standard. Either water quality-based or technology-based effluent standard could be adopted on the basis of the scientific rationale. Since it is important to set the regulation acceptable to both of environmentalist and developmentalist, reasonable background in areal classification and industrial categorization is required as well as scientific background. This study focused on Korean effluent standards from the past to the future covering how to set the regulation based on the approaches employed in well-developed countries. Except the area where strong protection is required, the regulation should be applied according to the type of discharge, that is, direct or indirect discharge. Industrial categorization should be carried out with the collection of wastewater data to reflect the characteristics of wastewater in the regulation. As a way of improving the allowable level of pollutant discharged, it was proposed that conventional pollutants to follow technology-based standard, whereas toxic pollutants would be appropriate to water quality-based standard. The lognormal distribution based on the effluent concentration data was considered to be reasonable for the regulation of conventional pollutants. The water quality standard implying risk assessment with 10 times dilution ratio was used to derive toxic pollutant standards.

Address correspondence to Jin-Young Jung, Department of Environmental Engineering, Yeungnam

Establishment of Effluent Standards for Industrial Wastewaters in Korea: Current Issues and Suggestions for Future Plan

Ijung KIM*, Sung-Hoon HONG**, Jin-Young JUNG***

* Department of Civil, Architectural and Environmental Engineering, University of Texas at Austin,1 University Station, Austin, Texas, U.S.A

** Environment Division, Korea Institute of Science and Technology, 39-1 Hawolgok-Dong, Seongbuk-Gu, Seoul 136-791, Republic of Korea

*** Department of Environmental Engineering, Yeungnam University, 214-1 Dae-Dong,

Gyeongsan-Si, Gyeongsangbuk-Do 712-749, Republic of Korea

ABSTRACT

Industrial wastewaters have been strongly controlled by effluent standard Either water quality-based or technology-based effluent standard could be adopted on the basis of the scientific rationale Since it is important to set the regulation acceptable to both of environmentalist and developmentalist, reasonable background in areal classification and industrial categorization is required as well as scientific background This study focused on Korean effluent standards from the past to the future covering how to set the regulation based on the approaches employed in well-developed countries Except the area where strong protection is required, the regulation should be applied according to the type of discharge, that is, direct or indirect discharge Industrial categorization should be carried out with the collection of wastewater data to reflect the characteristics of wastewater in the regulation As a way of improving the allowable level of pollutant discharged, it was proposed that conventional pollutants to follow technology-based standard, whereas toxic pollutants would be appropriate to water quality-based standard The lognormal distribution based on the effluent concentration data was considered to be reasonable for the regulation of conventional pollutants The water quality standard implying risk assessment with 10 times dilution ratio was used to derive toxic pollutant standards

Keywords: effluent standard, technology-based, water quality-based

INTRODUCTION

Though industrial development has led to economically affluent society, environmental problems such as climate change and shortage of water supply, have been returned Since industrial wastewater is one of the representative point sources, its portion in overall water pollution is significant in terms of the quality as well as the quantity The most common way to manage industrial wastewater is to apply environmental regulations such as effluent standards Although most developing countries are applying effluent standards along with water quality standards to monitor the quality of the watershed, many of those are not from their own effluent guideline, but just from other

countries’ standards (Ragas et al., 2005)

As a legal enforcement, effluent standards have been designed to regulate the end-of-pipe wastewater dischargers However, simply cutting down the allowable concentration of the pollutants in wastewater is considered to be costly and temporarily

expedient (Abou-Elela et al., 2007), even if it might guarantee a better water quality

Therefore, the regulations are required to be reviewed regularly to achieve a consented control and to show continuously changing situations In the case of U.S., the scheduling and implementing of annual review for the effluent standard are imposed by the Environmental Protection Agency (EPA) As stringent regulations could be applied

by the technological advancement in wastewater technology (Jaffe et al., 2002), the

revision of the effluent standards is facing new aspects in terms of treatability with reasonable basis Especially, Organisation for Economic Co-operation and Development (OECD) has been encouraged to use the best available techniques to prevent water pollution (OECD, 1999)

The regulation covers a complexity of various elements including discharging area, type

of discharge, and kind of industry Therefore, the need for a simplified effluent guideline

has been suggested (De La O et al., 1994) By selecting critical variables to be

considered in setting effluent standards, effluent guidelines could be organized in a less complicated form This approach would be beneficial to other developing countries as well

In Korea, although the effluent standard went through several revisions, reasonable basis of the regulation has not been established yet As an effort of setting the regulation based on treatability, it is required to collect wastewater data as much as possible In this study, the approach in setting the effluent standards with a limited data set obtained so far according to the kind of pollutants and industries was investigated This paper focused on the current state of effluent standards in Korea and the considerations to be used in revising effluent standards and the framework referring to the cases of developed countries The purpose of this study is to set up the acceptable level of effluent standards with scientific basis and to suggest a direction of the effluent guidelines which can make industrial point sources scattered all over the country gather into public wastewater treatment plants, resulting in a better control of individual wastewater dischargers

METHODS

Bases of effluent standard

In general, water quality standard is set prior to effluent standard because the cleaner the effluent, the cleaner would be the water systems Water quality standard starts from water quality criteria based on risk assessment The United States EPA proposed the process of setting water quality criteria concerning both human health (US EPA, 2000) and aquatic life (US EPA, 1996) For human health, risk assessment is applied differently according to the carcinogenicity of the pollutant Reference dose is used as

an important parameter in the derivation of safe concentration in case of carcinogens, whereas another concern on non-carcinogens is to evaluate the reference source contribution For aquatic life, the determination criteria are highly dependent on acute and chronic toxicity data provided by an officially approved database system such as Ecotox (US EPA, 2008) To get more reliable criteria, it is crucial to collect sufficient data from various taxonomical groups such as fish, daphnia and algae From the criteria derived by risk assessment, water quality standards can be adjusted by the regional classification, that is, the designated use of a specific watershed

After confirming the water quality standard, effluent standard can be set according to dilution ratio, treatability, economic feasibility, and other factors Two kinds of approaches in setting effluent standard are water quality-based approach and technology-based approach

Water quality-based approach

The key components in water quality-based approach are water quality standards and models As mentioned above, the methodology to set the water quality standards contains the principle of risk assessment Scientific data of bio-assay rather than industry data should be gathered In risk assessment, acute and chronic toxicity can be represented as LC50 (median lethal concentration) / EC50 (median effective concentration) and NOEC (no observed effect concentration), respectively The toxic effect onto human and aquatic life is evaluated separately Considering toxic effect and data collection, this approach is better applied to toxic pollutants Safety factor in the range of 10-1,000 is used in EU (EU, 2000) and Australia (ANZECC, 2000) The calculation of the water quality criteria is shown in equation (1)

50 50

LC , EC or N O EC

W ater Q uality C riteria =

U ncertainty factor (10~1,000)

Water quality standards are determined through the water quality criteria In Korea, water quality standards were set up by considering the drinking water standards and the economical and technical availability Because water quality standards express the quantified level of water quality, appropriate selection of models can guarantee the water quality-based effluent standard According to the characteristics of watershed, various models can be applied The simplest model comes from the following equation (Ross, 1994)

1 2 3 1 1 2

2

(F +F ) C -F C

C =

F

where, F1 : upstream flow

F2 : discharge flow

C1 : concentration in upstream

C2 : concentration in discharge (effluent standard)

C3 : concentration in downstream (water quality standard)

Technology-based approach

Acknowledging the limitation of treatment technology, technology-based approach has appeared in view of treatability In developed countries such as US and EU countries, technology-based approach was adopted as a feasible way in social, economical and technical compromise (US EPA, 1996; EU, 1996) Technology-based approach is often referred to as the best available technology (BAT) approach This approach is being used in the EU and US What is important in BAT approach is the thorough analysis of the industry including treatment facilities, as well as effluent characteristics Though it

is desirable in long-term, it takes too much time and effort making it difficult to apply in developing countries Using the easily assessable data which is the concentration in the effluent, the logical argument could be established by a statistical support Statistical approach (Wheatland, 1972) was found to be required in setting the effluent standards

(1)

(2)

-of a sewage treatment plant Regression -of the effluent data could be a key concept in setting the effluent standards (Kahn and Rubin, 1989)

To derive the effluent standards by the technology-based approach, the effluent quality from wastewater treatment should be monitored and recorded to be converted into a concentration-frequency graph which can be assumed as a probability distribution such

as normal, lognormal or delta-lognormal distribution Through statistical analysis, effluent standard by technology-based approach is determined In the US, lognormal distribution or delta distribution which shows reasonably good fit to various effluent data, has been used in the calculation of the effluent standard The approach by effluent data and statistical fitting can be used to suggest practical level of effluent standard rather than the required one The 95th percentile approach (Crain, 1995) has been used to derive monthly average effluent standard in the US

Combining both approaches can be a good solution to set the effluent standard in develo

ping countries (Ragas et al., 2005) Wherever Total Maximum Daily Loads (TMDL) is

established, the water quality-based approach employed by US EPA (US EPA , 1991) can be applied Although water quality-based approach is sufficient only to keep the water quality standard, it can impose overburden with individual treatment facility, even to economically infeasible level Therefore, technology-based approach can be a c omplement to water-quality based approach The important concept of technology-base

d approach is to set the level of effluent standard so that the treatment facility can meet t

he regulation

Each effluent standard derived from both approaches is compared to determine which value or range is reasonable to satisfy water quality standard and technologically feasible level Unless the safety of water quality is guaranteed, the regulation could rely

on water-quality based approach with the benefit/cost analysis which helps the

decision-maker to predict the result of regulation (Arrow et al., 2008) Through social

compliance to the degree which the stakeholders can agree with, effluent standard can

be finally confirmed

So far, effluent standard in Korea is considered to be subordinate to water quality standard However, it is required to evaluate effluent standard as an independent regulation and to revise it based on the methods employed in well-developed countries

RESULTS AND DISCUSSION

Overview of effluent standard in Korea

Once a pollutant was included in the effluent standard, the allowable concentration stated remained constant for more than 20 years with the exception of a few cases The main reason is that there was no basis of effluent standard, resulting in just following other countries’ cases In getting the numeric value to control the amount of pollutant discharged, it is difficult to avoid being controversial due to various viewpoints of stakeholders In brief, it can be described as a debate between protection and development; an effort to get clean and safe water and a desire to reach an economically developed society Above all, sustainability can be the conceptual solution to manage it

(Costanza et al., 1991), covering both ecological and economic aspects Also, science as

an advanced support of policy-making is required to involve the public sector (Cortner, 2000)

Pollutants regulated in effluent standard

The concept of effluent standard in Korea emerged in the middle of 1960s with the enfo rced ordinance of pollution prevention Although it has been revised continuously, the re sults were just an increase in the number of pollutants and a decrease in the level of allo

wable concentration, mostly depending on chemical analyses (Choi et al., 2004) The nu

mber of pollutants regulated under effluent standards was initially 7, and now it increase

d to 32 (Table 1) It seems that the range of control was greatly increased, yet it is still s mall when compared to the number of pollutants regulated in well-developed countries l ike Japan which regulates 42 pollutants and the U.S which has 65 toxic pollutants to be controlled Because new pollutants in Korea are assessed and selectively included into e ffluent standards by framework for classifying toxic substances in water environment (B

ae et al., 2007), it is expected that the number of pollutants would be increased up to the

level of well-developed countries The pollutants recently included can be classified int

o a group defined as toxic pollutants in U.S (US NARA, 2007)

Especially, ecotoxicity which is the same parameter as the whole effluent toxicity (WET ) in Korea has been adopted to unlimitedly manage increasing pollutants with the advan cement of analytical tools The WET regulation checks whether more than 50% of organ isms (fish, daphnia, algae and others) under toxicity test survive or not when they are dir ectly introduced to the discharged wastewater Wastewater is directly applied in protecte

d area, while twice diluted wastewater is used in normal areas, as a tool to investigate th

e total toxicity on human health and aquatic lives Now it can be easily found that WET,

as a complementary tool to chemical approach of the regulation, already took a part of effluent regulation with legal enforcement in other countries (Environment Agency, 2006; Germany, 2004)

Nowadays, 32 pollutants (Table 1) officially regulated in Korea can be classified in the f ollowing groups

Conventional pollutants

Biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended solids (SS), total nitrogen (TN), and total phosphorus (TP) are classified in the conventional pollutants They are the most representative and common groups in water pollutants Hence, they have been widely used in water quality index, and it is easy to accumulate the effluent data of this group

Toxic pollutants

Toxic pollutants are the chemicals which can cause fatal threat to human and eco-system even at low concentration They are categorized as priority substances (EU, 2000) or toxic pollutants (Khan and Rubin, 1989) In Korea, 22 pollutants among 32 are included in the toxic group This group is relatively difficult to analyze in general, and is expected to increase in number due to the advancement of analysis It is required to pay attention to select pollutant regulated according to industry

Other pollutants

The rest of the pollutants are grouped as other pollutants The pollutants under this group contain pH, temperature, color, total coliform and ecotoxicity They are not

expressed in mg/L, unlike the other specific chemical compounds As the universal characteristics appeared in almost every industrial effluent to some extent, other pollutants could also be applied to all of the industries except color Color has been reported to appear uniquely high in specific industries such as dyeing and textile industry In this study, this group was not considered to be changed in setting the effluent standards

Table 1 - Pollutants regulated under the effluent standards in Korea (Ministry of

Government Legislation in Korea, 2009)

Areal classification in effluent standard

According to the beneficial use of the watershed where wastewater is discharged, the level of allowable amount of pollutant can be set For example, the area where strong protection is required such as drinking water, has normally strict effluent standards specialized for its limited area Moreover, aside from national standards, effluent standards can be applied differently by the local government, making the application more flexible to specific conditions While the protected area was established so far, there has been a little concern on local standard Therefore, once national standard is set,

it is applied all over the nation Now, four areas are defined in effluent standard;

protected area, normal I, normal II and special area, which is strongly controlled by the central government

Though the regulation of indirect dischargers is the same as that of direct dischargers in Korea, there are other countries’ cases (US EPA, 2004; Germany, 2004; EU, 2001) showing that separate effluent standard which was less strict for indirect dischargers could be set in the tolerable level not causing problems to the operation of Publicly Owned Treatment Works (POTWs) Although there has been no problem concerning indirect dischargers in national-level regulation, separate effluent standard has been applied since 1991 The distribution of publicly owned industrial wastewater treatment and sewage treatment systems where separate effluent standards are set is shown in Fig

1 More than 95% of industrial wastewater treatments have their own effluent standard while sewage treatment systems are sensitive to receive industrial effluents so it is not a simple process to confirm its safe operation Therefore, it is also required to induce individual wastewater dischargers to industrial wastewater treatment facilities rather than to the sewage treatment systems

Table 2 - Areas in Korea and their water quality standards

Effluent standard (mg/L)

Normal I area (1 mg/L < BOD ≤ 3 mg/L) Ib, II 60-80 70-90 60-80 Normal II area (3 mg/L < BOD ≤ 10 mg/L) III, IV, V 80-120 90-130 80-120 Special area* Secondary effluent standard 30 40 30

*Area around watershed where POTWs discharge has the specific standard (BOD 10 mg/L, COD 40 mg/L, SS 10 mg/L) that has been effective after 2008

Fig 1 - POTWs which have separate effluent standard in Korea (a) Industrial

wastewater treatments (b) Sewage treatment systems (Black : with separate effluent standard, Gray : without separate effluent standard)

Categorical effluent standard

Effluent standards have been transformed from uniform standard to categorical one according to the wastewater characteristics (Tilche and Orhon, 2002) Industrial categorization was once adopted in the middle of 1970s After that, various effluent

standards according to the industries were applied but it was soon returned to uniform regulation in 1983 Although 82 industries based on standard industry categorization were officially included in Korean legislation related to effluent standards, categorical application of effluent standards has not been used for nearly 20 years

As an intermediate step that seems to be a stepwise improvement (Von Sperling and Chernicharo, 2002), it is desirable to set slightly stricter effluent standards than before, conforming to the existing status The site visit and data acquisition were required to be conducted together continuously to increase the number of effluent data Since there is limitation to get data in the effort of government solely, monitoring and reporting requirements are necessary to be imposed on the industries In part, the role of local governments might be increased in gathering and arranging data from industries located under their authorities

Since industrial categorization was not reflected in the effluent standard, industrial categorization in effluent standard is now commonly determined to be feasible in the regulation (EU, 1996; US NARA, 2007) If industrial categorization is included in the effluent standard, the most important factor is whether the categorization is based on the similarity of wastewater characteristics If the categorization simply follows the system

of industrial classification, the characteristics can be varied seriously even in same category Therefore, extensive investigation throughout the all the industries should be carried out

Improvement of effluent standard in Korea

As a way to get the reasonable basis for conventional pollutants which the effluent data have been accumulated for years, effluent standards can be derived from statistical analysis Briefly, the process of setting effluent standard by statistical analysis consisted

of four steps (Fig 2); gathering long-term effluent data, transitioning to relationship between concentration and frequency, applying to probability distribution and deriving effluent standards by mean and standard deviation Specifically, variability factor (US EPA, 2002) covering the fluctuation of effluent data in the well-operated plant, is multiplied with the mean of effluent data to get the values of 99 percentile or 95 percentile in the probability distribution The 99 percentile and 95 percentile are maximum daily limitation and average monthly limitation, respectively Since the concept of daily maximum is not included in Korea, it is recommended to adopt the 95 percentile as effluent standard, covering as many effluent data as possible

Col 2 vs Col 1

Concentration (mg/L)

0 20 40 60 80 100

0

Time (days)

0

2

4

6

8

10

3 Probability distributional assumption 4 Derivation of effluent standard

Effluent standard (95 percentile) = μ + 1.645σ (In case of normal distribution, μ: average, σ : standard deviation)

Fig 2 - Setting effluent standard by statistical analysis

Fig 3 - Frequency of detection according to COD and total nitrogen concentration in

metal assembly industry (Ministry of Environment in Korea, 2007)

As shown in Fig 3, the frequency distribution seems to be a kind of lognormal distribution expressed in x=exp(y) After fitting to the x=exp(y), the 95th percentile of x (x.95) can be calculated by the following equations

k

kln x =

n

2 k

=

n



where,  = mean of sample

 = standard deviation of sample

n = number of sample

.95

x = exp(1.645)

(4)

(5)

(6)

Based on the method mentioned above, the technology-based standard was found to be more stringent than the existing one, implying that the existing standard was not successful to reflect the actual discharge condition In case of metal assembly industry,

TN and TP standards were proposed as the values decreased 17% and 63%, respectively

Table 3 - Comparison of conventional pollutant standards in metal assembly industry

Pollutant (mg/L) BOD (mg/L) COD (mg/L) SS (mg/L) TN (mg/L) TP

Technology-based

In numeric values of national effluent standard, toxic pollutants which have water quality standards mostly get effluent standards 10 times higher than water quality standards (Ministry of Environment in Korea, 2001) This is one way of setting the effluent standards from water quality standards, that is, a kind of water quality-based approach Unfortunately, due to the lack of database of effluent quality from individual wastewater dischargers, technology-based approach is hard to be applied for toxic pollutants in Korea What is required to revise the effluent standard framework is to get independent logics in setting the effluent standards, continuing to accumulate as many reliable effluent data from industries as possible As treatability is based on the data accumulated in a long-term, how to set the infrastructure to get the data is a crucial factor in setting the effluent standards The following assumptions can be used in calculating water quality-based effluent standards in water quality-based approach

- There is no concentration in upstream

- Dilution ratio is the ratio of water quality standard and effluent standard

W astew ater flow + R eceiving w ater flow

D ilution ratio =

W astew ater flow

When dilution ratios were calculated among the main streams which receive more than 10,000 m3/year of wastewater, it was found that the dilution ratio, even at a dry season (minimum dilution ratio), was more than 10 (Table 4) Therefore, applying 10 times to water quality standard can be reasonable, assuming simple dilution of wastewater discharged in watershed Effluent standards of several toxic pollutants as shown in Table 5 were set with dilution ratio of 10

(7)