T 0137/83 15-04-1986

1. The appeal complies with Articles 106 to 108 and Rule 64 EPC and is, therefore, admissible.

2. There is no formal objection to the current versions of the claims since they are adequately supported by the original disclosure.

Claim 1 combines original Claims 1, 2 and 6 and incorporates features of the description (page 3, lines 23-29; page 4, line 30 to page 5, line 3; page 5, line 29 to page 6, line 7; page 6, lines 16-33; page 7, lines 9-23 and page 8, lines 13-20).

Claims 2 to 7 correspond to or are based on original claims 5, 3, 4, 8, 9 and 10 respectively.

The Board considers that the claims are clear (Article 84 EPC). Indeed the feature of adjusting the pH to prevent dissociation (impliedly where necessary) is not in contradiction with the fact that some compounds covered by Claim 1 do not dissociate.

3. The application relates essentially to a process for removing organic material from water contaminated therewith, the organic material being a chlorinated phenol, a phtalate ester, a phosphate ester, a phosphorothioester, a chlorinated benzene, a chlorinated biphenyl, a polynuclear aromatic compound, a chloroalkene, a chlorocycloalkene, a chloroether having a normal boiling point in excess of 200°C.

4. The application has been rejected by the first instance on the grounds that the subject-matter according to Claim 1 did not involve an inventive step with regard to Thibodeaux's article taken alone. The other document quoted in the Reasons for the Decision was relied upon for a different purpose.

After consideration of the true teaching of the State of the Art and for the reasons given later in this decision, the Board is of the opinion that the closest document of the relevant state of the art is the "K. Uede abstract".

5. There is stated that, in view of the widespread application of PCP as a widespread weed killing agent, it is probable that it contaminates drinking water. The problem with which the authors of the article were concerned was the one of finding a method for removing this contaminant. Experiments had shown that activated carbon was most effective for removing it.

6. Starting from this closest prior art document, the technical problem underlying the present invention was to provide an efficient and economically attractive alternative method to remove pentachlorophenol as well as other organic contaminants in water such as those produced, for instance, in the pesticides industry (description page 5, lines 3-22) with a boiling point in excess of 200°C.

7. The problem is essentially solved by the Appellants by a process comprising vapor stripping of the contaminated water under the conditions indicated in more detail in the cited Claim 1.

In view of the result of the 30 examples given in the description relating to PCP, other chlorinated phenols, diphenyloxid, trichlorobenzene and the further 15 compounds listed in Tables II and III of the application, the Board is satisfied that the problem is effectively solved.

8. As the solution claimed by the appellants is quite different from the solution of the closest prior art "K. Uede abstract", there is no objection to the novelty of the subject-matter of Claim 1. It has to be added that the first instance did not question the novelty when considering the rejected Claim 1, even in consideration of "Thibodeaux's article". The Board is of the same opinion and the reasons therefore can be derived from the next paragraphs.

9. The Board in agreement with the Examining Division considers that "Thibodeaux's article" is a very relevant document of the state of the art.

9.1. In this document a literature survey of common organic pollutant constituents is given comprising chlorinated solvents, chlorinated hydrocarbons, nitrobenzene, nitro compounds, phenol wastes, phenolic compounds, phenol derivatives, dichloroethyl ether among others (see pages 360 to 362).

Table I (page 362) contains a brief summary of relative volatilities and Henry's Law constant for common industrial gases and liquids and also quotes the normal boiling points. The accompanying comment to the table states firstly, that "many of the common liquid species are more volatile than water and will therefore desorb readily as indicated by a relative volatility greater than one". Secondly, it adds that "although some high molecular organics may have low pure component vapor pressures and high boiling points compared to water, they nevertheless exhibit large relative volatilities due to large activity coefficients in water".

Reference is made to activity coefficients of 103 to 107 for n-esters, n-ethers, n-chlorides, n-alkylbenzenes among others (see page 362). According to the article, experiments have been made on waste water samples from industry. The pH of the samples was adjusted to 3,0 or lower (see page 368, column 2).

Table 6 contains the percentage removal of each of 11 species (see page 371). Finally, Thibodeaux repeats that air stripping is another unit process capable of removing even organics with relatively low vapour pressure. He adds that, in fact there are probably many industrial treatment systems in which organics are actually being air stripped from the waste water, although their removal is erroneously attributed to biological oxidation (see page 374). When read in context with the introductory statement that air stripping had been demonstrated to be a feasible technique for removing a portion of the organics from waste water (page 358, sentence bridging columns 1 and 2), at a first glance, it would appear that Thibodeaux's article gives to its reader all the instructions necessary to start experimentation in every water contamination situation.

9.2. Nevertheless, the Board is of the opinion that a careful examination of this article leads to a quite different teaching to the man skilled in the art.

Even if Thibodeaux's article gives a general literature survey of organic pollutant constituents, no removal of the contaminants defined in the claim is reported.

One reference is cited reporting 99.9% efficiencies in removing phenolic type compounds, but it is added that it was the result of bio-oxidation and that the reference did not mention the role of air stripping (page 358, column 2, last 4 lines.

In Table I (page 362), the compounds 10 to 20 comprise, according to the author, a representative cross section of industrial organic chemicals in waste water. It must be admitted that all these considered pollutants have a normal boiling point clearly lower than 200°C, phenol being the last, with the highest boiling point (181.4°C). Consequently, it must be concluded that air stripping has not been examined for contaminants having boiling points in excess of 200°C. However, some relation is clearly disclosed between the normal boiling point, on the one hand, and Henry's Law constant and relative volatility of the organic compounds, on the other hand.

From Table 6 (page 371) which gives the percentage removals by air stripping for compounds 10 to 20, the skilled man can appreciate a drop in the percentage removal down to 5.4 for the phenol, which is the quoted compound with the highest boiling point (181.4°C).

Taking these facts into consideration, the Board is not inclined to give much weight to the accompanying comments to the tables.

9.3. It must be stressed that, due to the undesirability (for instance the toxicity) of the contaminants, only an efficient process could be considered as an alternative to the known and proved process (99.9% for phenolic type compounds by biooxidation). Although it is true that the skilled man could have tried air stripping for all sorts of contaminants, it appears clearly that faced with the existing problem, he could not have expected satisfactory results by such technique, in view of the teaching of "Thibodeaux's article" (5.4% for phenol, see Table 6, page 371).

Consequently, in view of the existence of other promising methods, the skilled man would have refrained from such an attempt. Nevertheless, the appellants have shown that, under the conditions of Claim 1 of the application, an efficient recovery of compounds boiling above 200°C is obtained. The per cent recoveries lie between 46 and 98 for 15 compounds listed in Table II of the application. For PCP, 99% removal was obtained (Example 1). This is a quite unexpected result in view of the fact that phenol, boiling above 100°C (lower than PCP) was removed by air stripping only to the extent of 5.4%.

The Board sees in the specific data in "Thibodeaux's article" a strong disincentive to using the stripping method for removal of contaminants boiling above 200°C when other proven methods were available. Among the generally known purifying methods the quoted prior art specifically mentions biooxidation ("Thibodeaux's article") and carbon adsorption ("K. Uede abstract").

10. In this context, it is interesting to compare this conclusion with the independent conclusions reported in the "USEPA Report" submitted by the appellants with their letter received on 10 December 1985 (see page 5, III(2)1., and Appendix A) which supports the position of the Board. As this report was not available to the public before the priority date, but only in the priority interval this document is not part of the state of the art. Nevertheless, it can be considered as an illustration of the thought of experts in the art at the relevant date.

11. Having considered the facts, the Board comes to the conclusion that the solution of the existing problem was not obvious to a skilled person because of a clear disincentive in the teaching of Thibodeaux, particularly in relation with the necessary efficiency in removing the contaminants covered by Claim 1.

Thus the process claimed in Claim 1 must be considered as not only new but also inventive. In view of the fact that the technique of vapor stripping of the contaminants from the contaminated water was not obvious, the question can be left open whether or not other features specified in Claim 1 contribute to the inventive step of its subject- matter. The subject-matter of Claims 2 to 7, which are fully dependent on the main claim are supported by the patentability of the subject-matter of the main claim.

12. The Board cannot therefore agree with the grounds and conclusions of the impugned decision of the first instance. However, the patent applied for cannot be granted at present as the description in the specification has not yet been brought into line with the claims as amended and does not indicate the useful background art (Rule 27 CBE).