T 0279/92 (Wastewater treatment/ZIMPRO PASSAVANT) 19-05-1994

Reasons for the Decision

1. The appeal is admissible.

2. New Claim 1 differs from Claim 1 as originally filed by the additional requirements that the lower portion of the quiescent zone opens into the lower portion of the aeration zone and that the treated wastewater passes through the opening in the lower portion of said quiescent zone. These amendments are apparent from the Figures and the description thereof (page 11, line 24 to page 12, line 10 of the originally filed application), so that the requirements of Article 123(2) EPC are met. The admissibility of the amendments was in fact not disputed in the contested decision. Claims 2 to 22 are the same as in the original application, though Claims 2 to 4 appear on a retyped page. Pages 5 and 6 have been amended to correspond to the amended Claim 1 and so are admissible for the same reasons as this claim.

3. Since none of the prior art documents on file discloses a process having all the features of Claim 1, the subject-matter of Claim 1 is novel. Novelty was not disputed in the contested decision.

4. According to the Examining Division, (2) represents the closest prior art, because it was considered that therein all of the features (a) to (d) of Claim 1 are already disclosed. To the Board it is however not apparent that the requirement of step (a), namely that the lower portion of the quiescent zone opens into the lower portion of the aeration zone, is actually disclosed in this document.

The following speaks against the interpretation made by the Examining Division:

Figure 1 of (2) shows a schematic representation of a reactor into which a settling zone is integrated, which is closed at the bottom. It is worthwhile to note that the settling zone indicated in Figure 1 is called "solids-liquid separator section" on page 200, right- hand column, last paragraph. Thus this section is not a quiescent zone in the meaning of present Claim 1, but rather is similar to the clarifier (settling tank) 13 of (1). The separation section has been integrated into the PAC-AS reactor to obtain a compact laboratory scale apparatus.

The fact that (4), Figure 6.4-23 shows a large scale installation with a built-in clarifier, which opens into the lower portion of the aeration zone, does not imply that the settling zone of Figure 1 of (2) is also of such a construction.

In view of this and in the absence of any specific description in (2) how transfer between the aeration zone and settling zone occurs, Figure 1 suggests that transfer occurs merely by overflow at the baffle. Consequently, (2) appears to disclose only a laboratory scaled version of the standard PAC-AS reactor.

4.1. Since the application relates to a full scale wastewater purification treatment, it is more realistic to consider (1), which discloses the standard PAC-AS process, as the closest prior art.

This document describes a process for purifying wastewater containing organic and adsorbable pollutants, comprising a treatment zone wherein the wastewater is aerated in the presence of powdered activated carbon and activated sludge, followed by a clarifier for settling the carbon and the sludge and separating the purified water (see, pages 9 and 10 of the description and the Figure).

The process of present Claim 1 differs therefrom essentially by creating in the primary treatment zone a quiescent zone from which the treated wastewater is transferred to a contact zone, wherein the wastewater is agitated in the presence of a powdered adsorbent, introduced into said contact zone, followed by a settling period to produce a clarified aqueous phase.

4.2. On the available evidence, the Board does not accept that the technical problem can be defined as submitted by the Appellant, as being to improve the purification performance of the PAC-AS process such as disclosed in (1) when dealing with wastewater containing pollutants which are difficult to biodegrade and only weakly adsorbed on adsorbents such as powdered activated carbon, while at the same time avoiding the need for the separate, conventional clarifier stage utilised by the standard PAC-AS process.

Although improvement of the purification performance might have been an object aimed at by the inventor, there is no proof available, that such an improvement was actually obtained. Neither the description nor the submissions of the Appellant contain any concrete data from which the alleged improvement is apparent. Alleged but unsupported advantages cannot be taken into consideration when defining the problem underlying the claimed invention; cf. T 20/81 (OJ EPO 1982, 217).

In relation to said closest prior art, the Board considers thus that the problem underlying the invention is to provide an alternative for the standard PAC-AS process.

This problem is to be solved by the process as defined in present Claim 1.

The description and Figures 1 and 2 of the patent application provide sufficient evidence that the stated problem has indeed been solved by the process with the features required by present Claim 1.

4.3. It is clear from paragraphs 4.1 and 4.2 above, that neither (1) nor (2) contains any information suggesting the use of a two-stage process, including an additional adsorption zone, for purifying wastewater containing organic and adsorbable pollutants. The same also applies to the other citations.

The two stage treatment mentioned in the abstract of (3), to which was referred in paragraph 3 of the contested decision, relates to a process wherein the first stage of the two stage treatment is a pure biodegradation stage. In such a case it makes sense to complete it with an adsorption stage; in the present case however, adsorption already takes place in the PAC-AS reactor. Moreover, (3) does suggest that the removal of even recalcitrant pollutants such as dioxins and PCB's is already substantially complete by a simple PAC-AS process (see column 2, lines 51 to 62).

The idea of replacing the clarifier in (1) with a quiescent zone in the primary treatment zone is linked to the notion that for the additional adsorption stage it is not necessary to have a complete separation of water and sludge as is obtained by a clarifier according to (1). This teaching is not disclosed in the prior art. The only document disclosing a quiescent zone in an aeration zone is (4). This document relates however to a pure biological purification reactor and mentions the necessity of an additional clarifier, which the applicant tried to avoid. Thus (4) in fact teaches away from the claimed invention.

The Board could find no support in the cited documents that the performance of the adsorption steps (f) to (i) mentioned in present Claim 1, namely introducing powdered adsorbent and agitating the aqueous phase and operating the adsorption in the fill and draw mode, is one out of several possibilities for an additional adsorption stage a skilled person would necessarily have envisaged. The contested decision indeed merely stated that the selection of this mode was well within the level of the skill of an expert, without however giving reasons in support of that allegation. Thus, the available prior art would not provide the skilled person with any incentive for solving the above mentioned problem by the combination of steps indicated in present Claim 1.

5. It follows from the foregoing considerations that Claim 1 is not only new, but also involves an inventive step in the sense of Article 56 EPC.

Since Claims 2 to 22 are all subclaims dependent upon Claim 1, their allowability follows from that of Claim 1 without the need for any separate consideration for novelty and inventive step.