When we carry out an activity during which waste is produced, we should plan, project and carry out these activities in such a way to avoid waste production or reduce its amount and negative impact on people's health and environment – both when goods are produced and after using them.

The above conclusion is a brief summary of some Polish regulations. Which ones? These are the regulations concerning managing waste which is produced as a result of stone processing. They are stated in the act as of 14 December 2012 on waste (Journal of Law from 2013, clause 21 with further amendments). Managing waste should take place according to a certain order, which is mentioned in article 17 of the waste act. Then, first you need to prevent waste production, but when it is impossible, waste must be recycled. The least appropriate is waste disposal, including storage.

- If activity, during which waste is produced, is related to operation of an installation, there is a need to obtain a permit on waste production, which is stated in article 180a in the act as of 27 April 2001 – environmental protection law (Journal of Laws from 2013, clause 1232 with further amendments). The permit for producing waste is required when exploitation may cause emission of hazardous waste amounting to more than 1 Mg per year or other non-hazardous waste (more than 5,000 Mg per year), says Katarzyna Pliszczyńska, a spokeswoman of the Polish Ministry of Environment.

- When we want to manage waste, article 41 of waste act applies. It says that collecting waste and processing waste requires obtaining a special permit issued by a competent authority (the Marshall of the Province, the District Governor) of the place of collecting or processing of waste. A regional director of environmental protection is the competent authority for issuing permits for collecting waste and permits for processing waste in enclosed areas. We need to remember that according to article 66 (1)s of the waste act, every person who has waste, including producers of waste, is obliged to keep quantitative and qualitative records (excluding situations mentioned in clause 4 of the above article). Moreover, according to article 75 (1) of the waste act, the waste owner (including waste producers) who keeps waste records is obliged to draw up an annual report on waste he produced and waste management. Entities obliged to draw up the above reports have to submit them by 15 March for the previous calendar year to the competent Marshal of the Province depending on the location of producing, collecting or processing waste (it applies to reports on produced waste and waste management).

Vertical clarifiers with filter bags are commonly found and dehydrators are a perfect solution for small stone companies, but automatic water treatment plants are, of course, the most effective. They are often found in bigger plants. No matter which solution we choose, it is worth going one step further.  

- Firstly, stonemasons should spare a thought if they do not waste their money, because grinding or cutting waste are perfect additives for concrete and there are technical approvals issued for this waste – encourages Grzegorz Skórka, a former employee of the Provincial Construction Supervision Inspectorate in Katowice.

- Secondly, we must note that using natural resources is more and more important for the legislator. For example, according to Annex 1 to the Regulation no 305/2011 of the European Parliament and of the Council as of 9 March 2011, it has been indicated that construction object as a whole as well as its particular parts must be fit for their intended use. Health and safety of people who use these objects for the whole life cycle of these buildings must be taken into account. Thirdly, it is worth recalling article 91 (2) of the act as of 29 January 2004 – public procurement law, where it is stated that environmental aspects may be one of the tender evaluation criteria. As a matter of fact, this criterion is not used too often (except for price, warranty and deadline are the most important in construction works), but possibly it may change with the growing ecological awareness (the ideas included in “Green public procurement” are currently being promoted).

Environmental policy in the whole Europe is more and more often shaped by the need to influence production activities in order to reduce the impact of production and then use and disposal of various products on environment. Sustainable industrial waste management requires introducing cleaner production which uses low-waste technologies as well as internal and integrated management of raw material flows. It refers to all possible actions which may reduce the amount of raw materials and energy which are used to create products, improve disposal of production waste and raw materials which are left as well as to ensure closed flow of raw materials and to avoid or find a substitute for particularly hazardous substances.

Proper waste management is a duty of every stone company. In practice, however, containers are often the only way of storing waste in production plants. It is a pity, because we proved that aqueous waste may be a remedy for growing needs of eco-friendly agriculture, eco-friendly gardening and eco-friendly horticulture! Publications written by experts show that, for example, stone powder contains almost all elements, minerals and micro-elements. One thing is certain: stone powder will be more and more often treated as a kind of reserve tank of fertilizers in the ground, which is gradually and slowly emptied. In other words, we can say that the one who uses stone powder practically should not or even cannot make a mistake in fertilizing! Due to this, stone powder is recommended particularly to beginners in gardening, fruit farming or farming who are just trying new eco-friendly methods (biodynamic agriculture).  

- Rock powder should be used in every horticulture. This waste can be used provided it is tested if there are any hazardous components and provided it obtains a certificate of product's competence – says Professor Kazimierz Klima from Hugon Kołłątaj Agricultural University from Cracow.  

So far ecological waste management has been most favourable for stone mines. The list of fertilizers and soil conditioners qualified for use in ecological agriculture can be found on the website of the Institute of Soil Science and Plant Cultivation in Puławy.

A common problem for most stonemasons may turn out to be an essential advantage of waste. This is the way of thinking of the owner of GRANIT-MAR company from Kościan who mastered the technology of natural granite dust recycling. A substitute for limestone (its sales name is Grano) has much better properties than Polish standards require. This is also proven by a certificate which proves the sense of using it as a substitute for limestone in masonry and plastering mortars. But also here the estimated demand for prefabricated elements fell flat.  

- Distrust prevails. Concrete plants prefer proven methods with the use of ashes, so I make prefabricated monument bases (for my own needs) out of the additive in the form of aqueous suspension. I store the surplus, but I haven't solved the problem of waste management this way – admits Mirosław Gryś.

As we know, sludge thickens through the action of gravity and gets the consistency of a thick mud. Is this another idea?

- Strongly hydrated sludge may be used as an input to batch concrete mix. It improves mechanical, operating and aesthetic conditions. Aesthetic ones as well because small stone elements may look beautiful with artificial LED lights – says Piotr Szmyt, BEng, a chief water technology and waste advisor of Hydrokraft.

- This is our licentia poetica, because we are in talks about funds for an innovative method. We know that sludge may play a significant role in the production of prefabricated elements.

But now most manufacturing companies have to use ad hoc solutions. Companies from Strzegom, for example, may count on Pracownicza Spółka z o. o. “GRANIT” over the decade. Waste from stone cutting and sawing is just a fraction of what is accepted here as part of the land recultivation.

What can we do with a very heavy and thick sludge? Now, let us have a look at this problem from the point of view of machine performance degradation. As we know, the degree of water recirculation in the technological process of sludge production depends to a great extent on suitability of a given sludge fraction to reuse and on allowed pollution level accumulated in the process. Our aim should be, of course, to increase the degree of water recirculation.   

Water in machines for cutting and processing stone plays two roles: it cools diamond tools and reduces their wear; dynamic water activity flushes grit out of working area. Flushed water with grit forms emulsion which, in case there is no water treatment plant, is supplied by a water pump back to the tool. What is the effect? Channels which supply water overgrow.

- Water demand is not small. CNC machines need a 10 litre-per-minute water flow. In case of Intermacc machines, we need five micron filters. If we neglect this, the drive becomes inordinately hot, which leads to faster degradation of windings and bearings. Let us remind, as a warning, that a new electro-spindle costs approximately 8,000-10,000 Euros – says Paweł Szczepanik from Mekanika company.

Cleaning CNC machines means a costly downtime. It often takes a day to bring back flow capacity of cooling channels. Water with stone grit also contributes to the wear of all movable elements and processing tools. What is worse, water polluted with grit turns into sediment which settles in collective containers. Compact and hard to remove planes are a real problem, because modern machines are more and more often equipped with plastic elements which makes attempts to get rid of sediment in an impact way impossible.

Grit is classified as a product of machining. Glass processing in the form of phasing, cutting or engraving is a typical abrasion of a surface. Whilst sludge is a term that can be applied only to urban and industrial waste water. So why did we speak about grit and not sludge when discussing water circuit in a stone company?

- Grit is a term applied only to abrasion processes and seems to be a more proper name for stone branch. This way we can explain the advantage of our in-house sedimentation technology, which is a process of separating suspension into clean liquid and residue – explains Piotr Szmyt, BEng.

- My company has been a forerunner of installations dedicated to glass industry, where grit is more difficult to manage. Post-production grits after glass grinding are 20 microns in diameter. In case of stone processing, we've got a 200-micron grit. Sedimentation in our installations occurs very quickly. Our idea is based on compaction of deposited sludge. The compaction, that is reducing sedimented grit in size, results in complete de-watering of sludge and sticking of very hard deposits whose consistency and firmness bring to mind … sandstones. Importantly, a chemical method can also help these processes.  By using magnetic processes, which is our secret, we can offer a premium version of the installation.

Some stonemasons have already got interested in this innovative method. Preventive qualities of installation constituted the most important argument. What can we say about costs of using installation like this? Not much now because collecting data has just started since the metered installations have been working for just a few months.

- I had a waste water treatment plant, but the machinery park which was situated at the other end of the area required an energy-consuming pumping of sludge from waste containers. The proposal by HydroKraft tempted me with an incredibly attractive price – says Antoni Młynarski, the owner of I-Mar company.

- Now water in a closed circuit reaches three saws. I really like the ecological value of the installation and the fact that electronics controls all cleaning processes. The difference is huge because cleanliness of the work areas in my company significantly improved.

It appears that technological water may work in a closed circuit – not including micro-defects  (evaporation, splashing water). Post-production waste? This issue seems to be “problematic” now and is waiting for innovators.