9. Economic Aspects
10.3. Detergent Laws
Detergents represent a typical and important group of environmental chemicals, i.e., substances entering the environment after their use. The per capita consumption of detergents is nowadays at a level considerably below the figures of the 1980s (1980:
33.3 g per capita and day in Western Germany; 1997: 21.1 g per capita and day in Germany). Nevertheless, the current annual consumption is in the range of 660 000 t/a (Table 44). These large amounts of chemicals go down the drain and enter receiving waters directly or after sewage treatment. Since the wastewater treatment situation was relatively poor in most European countries a few decades ago, it is not surprising that certain detergent ingredients, i.e., surfactants and phosphates, exhibited an apparent specific impact on the aquatic environment and became subject of specific laws and regulations.
Table 44. Consumption figures and average wastewater concentrations of ingredients of household detergents and cleansers (Germany, 1999)
Product ingredient Consumption, t/a [573] Per capita consumption, g/da
Calculated average waste-water concentration, mg/Lb
Total ingredients 688 000 23.0 177
Anionic surfactants 104 700 3.50 26.9
Nonionic surfactants 53 000 1.77 13.6
Cationic surfactants 30 400 1.02 7.8
Zeolites 139 000 4.64 35.7
Polycarboxylates 15 700 0.52 4.0
Na carbonate (soda ash) 98 800 3.30 25.4
Phosphates 23 600 0.79 6.1
Na citrate 15 600 0.52 4.0
Na perborate tetrahydrate 49 500 1.65 12.7
Na percarbonate 27 200 0.91 7.0
TAED 13 100 0.44 3.4
Phosphonates 2 900 0.10 0.7
NTA 400 0.01 0.1
Carboxymethyl cellulose 2 200 0.07 0.6
Dye transfer inhibitors 400 0.01 0.1
Silicates 22 300 0.74 5.7
Enzymes 6 000 0.20 1.5
Optical brighteners 500 0.02 0.1
Paraffins 1 200 0.04 0.3
Soil repellents 600 0.02 0.2
Perfumes 5 700 0.19 1.5
Dyes 100 0.003 0.03
Na sulfate 74 600 2.49 19.2
aPopulation in Germany (1998): 82 106[573].
bAverage per capita water consumption in households in Germany: 130 L/d (1998) [573].
Ecology
10.3.1. Development of the European Detergent Legislation
One of the earliest pieces of detergent legislation was the German Detergent Law of 1961 [2]. With its specific requirement for a minimum level of biodegradability, this law subjected a fundamental product parameter to legal control for the first time. The trigger for setting minimum biodegradability standards for synthetic detergents was the fact that the first generation of synthetic anionic surfactants was represented by the poorly biodegradable tetrapropylenebenzenesulfonate. The highly branched chemical structure of the anionic surfactant prevented its microbial degradation in sewage plants and rivers and caused formation of large mountains of foam in sewage treatment plants, weirs, locks and rivers in Germany, particularly during the droughtlike summers of 1959 and 1960. The law and the statute that followed (1962) [3] placed a strict requirement of at least 80 % biodegradability on all anionic surfactants. This legal move successfully displaced TPS from detergent formulations by the readily biodegradable linear alkylbenzenesulfonates. Thus, by 1965 foaming problems in German sewage treatment plants and surface waters had been eliminated.
In the late 1960s most of the European countries had limited the use of TPS in household detergents. Based on an agreement of the Council of Europe [577] requiring all types of surfactants to be biodegradable, the EEC released two directives on the biodegradability of surfactants in 1973: The EEC Directive 73/404/EEC stipulated an average biodegradability of at least 90 % for all types of surfactants used in detergents, i.e., anionic, nonionic, cationic and amphoteric surfactants [578]. The Directive 73/405/EEC described the biodegradability test methods to be applied for anionic surfactants and specified a minimum of 80 % degradation in a single test [579].
Table 45. Contribution of laundry washing (without laundry soil) to the chemical load of municipal wastewater Chemical load
Dry solid matter 450 7.65 72 10.6
Total nitrogen 7 0.12 12 1.0
Total phosphorus 2 0.03 2.4 1.0
*Derived from a water consumption of 17 L/d for laundry washing [576].
LaundryDetergents
On the national level these European Directives were translated into detergent laws by the member states, e.g., in Italy in 1974, France in 1977, The Netherlands in 1977, and the UK in 1978 [580]. In Germany the detergent law of 1975 [581] and its statutory orders of 1977 [582] and 1980 [583] regulated the “environmental compatibility of laundry detergents and cleansers”. According to § 1 (1) of the German Detergent Law placement of detergents and cleansers on the market is permitted only if the absence of all avoidable deterioration in the quality of surface water can be ensured. Particular attention is paid to the potential role of surface water in the drinking water supply and to problems related to the operation of sewage treatment plants. The general require-ments and authorizations for implementation apply directly to the following areas:
1) Unambiguous product labeling, including qualitative declaration of all significant components present
2) Deposition of frame formulations for all products at the Federal German Environ-mental Agency
3) Utilization only of biodegradable organic components, particularly surfactants and other organic compounds as specified in a statutory order
4) Provision of directions for dosage of detergents on all packages, including variations applicable to water of differing hardness, where hardness is defined in terms of four ranges
5) Obligation on the part of local water supply authorities to publish the hardness characteristics of their water
6) Limitations on permitted phosphate levels, including some cases of a total phos-phate ban, provided that ecologically sound substitutes are available (see Sec-tion 10.3.4)
Products covered by the Detergent Law include: household laundry detergents;
household cleansers; dishwashing agents; rinsing and other laundry aids; detergents for I&I laundries; industrial cleansers; and cleansing agents employed in the leather, tanning, paper, and textile finishing industries that might be released into wastewater.
Thus, the definition of detergent products according to the German Detergent Law is more comprehensive than the EU definition, that only covers surface active substances which are main components in detergents and designed for cleaning purposes [580].
10.3.2. Regulatory Limitations on Anionic and Nonionic Surfactants
The Directive 73/405/EEC [579] and its updated version Directive 82/243/EEC [584]
specify the minimum biodegradability of anionic surfactants contained in detergents. In addition, the procedures are described to be applied for measurement of biodegrad-ability. In close analogy the Directive 82/242/EEC [585] specifies an 80 % biodegrada-tion pass limit for nonionic surfactants used in detergents, and the test methods to be used. A corresponding national regulation has existed in the Federal Republic of
Ecology
Germany already since 1977 [582] (“Tensidverordnung”). The regulation requires a minimum of 80 % biodegradability for the anionic and nonionic surfactants present in a packaged detergent. Anionic surfactants are determined as “methylene blue active substances” (MBAS), i.e., materials forming a chloroform soluble complex with the cationic dye methylene blue. Nonionic surfactants are defined as “bismuth active substances” (BiAS), i.e., materials forming an insoluble complex with the bismuth-containing Dragendorff reagent [586].
Although not all anionic and nonionic surfactants can be analytically measured by the MBAS and BiAS method [587], these parameters are used for the evaluation of the biodegradability according to the legal requirements. Essentially, the percentage of MBAS or BiAS loss describes the disappearance of a specific analytical reaction of the parent surfactant. This loss of reactivity is due to microbial transformation of the chemical structure of the surfactant, resulting in the loss of typical surfactant properties such as surface activity and foaming power. Therefore, it is called “primary or func-tional biodegradation” (see Section 10.4.2.1).
10.3.3. Primary Biodegradation Test Procedures
According to the Directives 82/243/EEC and 82/242/EEC and corresponding na-tional legislations two types of test methods are applicable for determining the (pri-mary) biodegradability of anionic and nonionic surfactants, respectively. The first type is a discontinuous shake flask test operating with a low bacterial inoculum, that is incubated with 5 mg/L of MBAS or BiAS as the sole carbon source. In this OECD Screening Test [588] the loss of MBAS or BiAS is determined periodically up to 19 d. The results are compared with the degradation behavior of two control substances: the poorly degradable TPS (5 35 % MBAS decrease) and the readily biodegradable LAS (about 92 % decrease). The biodegradability determination in this test is illustrated in Figure 96. The second test type is represented by the OECD Confirmatory Test [588]
simulating the biodegradation process occurring in an continuous activated sludge plant (Fig. 97). In this procedure, MBAS (20 mg /L) or BiAS (10 mg /L) is dissolved in synthetic sewage (containing peptone, meat extract, urea, and mineral salts) and fed
Figure 96. Biodegradability evaluation in the OECD Screening Test
tA: maximum 14 d; tA+ tX: maximum 19 d --- examples for two surfactants; one is biode-grated more easily (tA) than the second one (tA+ tX)
LaundryDetergents
continuously into a model sewage treatment plant with a hydraulic retention time of 3 h. After inoculation of the test system with the effluent of a predominantly domestic sewage treatment plant and after growth of the activated sludge, the effluent is analyzed periodically. This running-in period lasts six weeks at maximum and is followed by a 21-d evaluation period after the degradation rate has become regular. The average degree of biodegradation during the evaluation phase is calculated as a mean value of at least 14 separate results based on samples from 24-h collection periods (Fig. 98).
The discussed test types represent a hierarchical system of the biodegradability evaluation. Usually, surfactants are evaluated on the basis of die-away screening tests such as the OECD Screening Test or the French AFNOR Test. In addition, the British Porous Pot Test, which is a continuous sewage-works simulation test, may be used at this stage of data generation [584], [585]. However, if the degradation proves MBAS or BiAS loss lower than 80 %, or if doubt remains, a subsequent confirmatory test is required, and the outcome of this OECD Confirmatory Test is regarded as definitive.
Figure 97. Experimental arrangement for the OECD Confirmatory Test as specified by the German Detergent Law
a) Sample container; b) Dosage pump; c) Ac-tivated sludge vessel (capacity 3 L); d) Settling vessel; e) Air lift; f ) Collection vessel; g) Fritted disk; h) Air flow meter
Figure 98. Determination of a rate of biodegradation according to the method specified in the OECD Confirmatory Test
Ecology
10.3.4. Regulation of Maximum Phosphate Content in Detergents
The detergent regulations at the European Union level address exclusively the surfactants and their biodegradability. However, at national levels, regulations or voluntary agreements on the phosphate content of detergents exist in many countries, e.g., Austria, Germany, Italy, The Netherlands, Norway, Sweden, Switzerland, USA, Canada, and Japan.
In itself, phosphate is not harmful but is a natural and essential macronutrient for all living organisms. Normally, the phosphate concentration of surface waters is so low that it is a limiting factor for growth of algae and higher plants. Consequently, when excess phosphate is released into the aquatic environment, the resulting overfertiliza-tion leads to increased growth of algae. Due to the concomitant secondary processes (organic load of waters, oxygen depletion after the organic bio-mass is microbially degraded) the overall water quality may be considerably reduced. Detergent phosphates released with laundry wastewater are quickly converted into orthophosphate. Thus, the use of sodium triphosphate in detergents came under critical scrutiny although many other phosphate sources exist that contribute to eutrophication of surface waters.
According to a profound study on phosphates in Germany in 1975, some 60 % of the phosphate contained in municipal sewage originated from detergents and cleansers [589]. As a consequence of the partial removal of phosphate in sewage treatment plants and the input of phosphates by other sources (human excretion, food industry, agricul-tural fertilizers), the share of detergent phosphates in surface waters was estimated to be about 40 %. This balance showed already that the reduction of phosphates in detergents is an important but not the sole factor in solving the eutrophication problem of surface waters.
The most comprehensive approach involves chemical elimination of phosphates in the sewage treatment plant (tertiary treatment) removing the total phosphorus content of the wastewater. This approach is realized in some countries to a greater or lesser extent. Nevertheless, phosphate reduction in detergents, i.e., at its source, provides immediate relief to receiving waters and, ultimately, also to the coastal areas of the seas, which are increasingly confronted with eutrophication problems.The phosphate regu-lation of 1980 [583] implementing the pertinent authorization of the German Detergent Law of 1975 (see Section 10.3.1) had a considerable impact on the development of the phosphate loads in German rivers (Fig. 99). The phosphate reduction in detergents was enforced in a two-step decree starting with an overall relative decrease of 25 % of the detergents' phosphate in 1981 and around 50 % in late 1983. The second step required the availability of suitable phosphate substitutes for detergents (see Section 10.5.2).
Their good performance in phosphate-reduced and -free detergents and the acceptance of nonphosphate detergents by the consumer has meanwhile led to a complete sub-stitution of phosphate-containing detergents by phosphate-free ones in many countries, for example in Europe in Germany, the Scandinavian countries, Italy, Austria, The
LaundryDetergents
Netherlands, and Switzerland (see Fig. 72). Thus, the legal requirements on reduction or banning phosphates in detergents have been superseded in many cases by the industrial supply of efficient phosphate-free detergents and their acceptance by the consumer.
The legislative pressure towards phosphate reduction in detergents accompanied by the availability of suitable substitutes has resulted in a noticeable quality improvement of a number of surface waters today [590]. Phosphate balances of the river Rhine in 1979 and 1989 showed that the measured phosphorus load reduction of about 28 400 t/a within this period corresponded very well with the expected phosphorus reduction due to the use of phosphate-reduced or -free detergents (26 700 t/a) [591].