WATER POLLUTION CONTROL DIRECTIVE TECHNICAL PROCEDURES DECLARATION

Transcription

1 WATER POLLUTION CONTROL DIRECTIVE TECHNICAL PROCEDURES DECLARATION Official Gazette: Dated 1/7/1991 and No Legal Baseline: Water Pollution Control Directive published at the Official Gazette dated and no CHAPTER I OBJECTIVE, SCOPE, LEGAL BASELINE Objective, Scope and Legal Baseline Article 1- This declaration is prepared according to the Environment Law dated 9 August 1983 and no 2872 and articles 7, 19, 23, 28, 30, 35 and 51 of Water Pollution Control Directive which is prepared in compatible with the law clauses which have annexes and changes in the mentioned law, encloses methods that are accepted as applicable in wastewater treatment; necessary information in determination of dilutions in deep sea discharge; irrigation criteria sought for using treated wastewater in irrigation; needed technical limitations and arrangements to avoid pollution of coastal water bodies due to septic tanks constructed on or around coastal sand band. Given in this declaration are, methods accepted as applicable for wastewater treatment in general, descriptive of these processes and in general characteristics, and do not limit the usage of present and/or new methods that are not included in this declaration, but the applicability is experienced, which can meet the discharge criteria predicted in Water Pollution Control Directive. CHAPTER II TECHNICAL LIMITATIONS ON SEPTIC TANKS Technical Elements to Be Implemented where No Sewage System is Present or where the Construction of the Sewage System is Impossible Article 2- In places where no sewage system is present and where the construction of the sewage system is impossible, the clauses of Regulation on Wholes to be Built in Places where Sewage System Construction is not Possible published at the Official Gazette dated 19 March 1971 and no by the Ministry of Health and Social Relief are valid. However, the following conditions and principles should be obeyed in this application. a) Septic tanks indicated in the above-mentioned Regulation could not be used to dispose wastewater of resident sites with a population higher than 500 people, holiday sites and industry plants. In this situation, the clauses of Water Pollution Control Directive on wastewater discharge should be obeyed. b) Septic tanks with multiple compartments cannot be used in regions where the population is higher than 500 during the tourism season as the water usage is more and due to the close vicinity of these facilities are more important in terms of pollution. In these places, wastewater treatment should be done through treatment technologies, defined within this declaration, whose technical efficiency and applicability is justified. c) In applications to be done within the framework of Water Pollution Control Directive and this declaration the main consideration is not the project of wastewater treatment plants, but the treated water quality. d) Even in places where the population is less than 500, septic tanks could only be used where precautions relevant to the biological treatment is taken and conditions foreseen in Water Pollution Control Directive is fulfilled flawlessly, as the mechanical treatment cannot satisfy much treatment efficiency. e) In residents where the population is between , wastewater could be treated in septic tanks with multiple compartments constructed in groups, where the output stream is diverted out of the resident site through pressure pump or gradient force. However, in this case limitations brought by Water Pollution Control Directive should be followed. CHAPTER III WASTEWATER TREATMENT METHODS General Technical Elements about Wastewater Treatment Plants

2 Article 3- Foreign substances causing pollution in wastewater could settle down, stay dispersed, colloidal according to their particle sizes or are solved in water. Each substance group could be moved away from wastewater through different methods. Methods applied in wastewater treatment could be grouped under three main groups as physical, chemical and biological. Among them, settleable or floatable particles are departed via settlement and floatation by physical treatment; solved or colloidal sized particles are coagulated and made settleable by chemical treatment; solved substances are partially transformed into easily settleable coagulants which are formed by accumulated biomass and partially into gases that emerge as a result of respiration done by microorganisms to obtain energy and other stabilized final products by biological treatment. In order to lessen the load of biological and chemical treatment units, first physical pre-treatment is applied. After pre-treatment which is named as mechanical treatment and which is composed of bars, grit chamber and primary settlement tank units, biological and/or chemical treatment can be applied. Coagulants formed as a result of biological and chemical treatment are taken away from wastewater through mechanical operations. Physical Treatment Units Article 4- Physical treatment units applied in treatment plants are bar screens, sieves, grit chambers, floating substance traps, stabilization tanks and floatation tanks. Bar Screens Article 5- Bar screens are used so as to avoid the damage of coarse materials in water to pump, pipe and equipment; to lessen the load coming to the other treatment parts or to separate coarse materials from water. Bar screens are classified according to their bar widths as fine and coarse bar screens; and according to cleaning method as manually and mechanically cleaned bar screens. Bar width in fine screens is mm, and in coarse screens is mm. The speed in bar screen canals should not be less than 0.5 m/sec in dry weather flow, the speed between the bars should never exceed 1.2 m/sec. Substances trapped at the bar screens cannot be stored at the treatment plant site. They are disposed through incineration, storage, composting and similar methods along with the domestic solid waste. Sieves Article 6- Sieves are used especially to trap fiber containing substance and suspended particles in wastewater treatment plants. These units are classified as coarse and fine sieves according to the sizes of the trapped substances. The sieve size is 5-15 mm in coarse sieves, mm in fine sieves and in micro-sieves. Wastes trapped at the sieves are also disposed with the same methods applied for bar screen wastes. Grit Chambers Article 7- Grit chambers are used so as to separate inorganic substances like sand, gravel from water, to avoid corrosion in the pumps and similar equipment in wastewater treatment plant and the clogging in settlement tanks. These structures may not be needed to remove industrial wastewater which does not include sand and similar substances. These are used to trap solid substances with a larger density than 2650 kg/m3 and with a larger dimension than mm. grit chambers should have the needed surface area to trap solid substances at a certain size and to hinder the settlement of substances with small particles which are planned to be treated in next coming units. Horizontal speed of the water in the unit should be designed as 0.3 m/sec for all flows to the plant. Grit chambers could be rectangle-designed long parallel flow and circular designed radial flow. In addition, aerated grit chambers are used successfully in most applications. Sand and gravel trapped in grit chambers are cleaned continuously in large plants via pumps running on pressurized air or mechanisms with band conveyors and spirals, from time to time in small plants via shovels.

3 Substances trapped at the bottom of grit chambers should not be disposed haphazardly as they contain a little organic material and pathogenic microorganism. They are also disposed along with domestic solid wastes, similar to bar screen wastes. Floating Substance Traps Article 8- Floating substance traps (grease traps) are used to separate floating substances like oil, grease and solvent which are present in wastewater and whose densities are less than water. In case there are no primary settlement tanks or ratio of these materials being too high, floating substance traps should be built so as to recycle these materials and to increase the treatment efficiency. Floating substance traps are constructed with sludge chambers enabling to take away the settled sludge and floating substances easily in case other solid substances other than floatable substances settle down the bottom of the tank. In order to separate the emulsified floating substances on the other hand, units like dispersed air floatation or solved air floatation are used. The most appropriate solution for municipal wastewater treatment plants are combined aerated sand and floating substance traps. Wastes trapped in floating substance traps are sent to incineration and revaluation plants. Stabilization Tanks Article 9- Stabilization tanks stabilizes the flow, contents and pollutant load in wastewater and orders the wastewater flow into the plant. Mixing is used to homogenize the content in stabilization tanks and to avoid the settlement of suspended particles. Sedimentation Tanks Article 10- Sedimentation is the separation of suspended solid substances with a density greater than water or solid substances which made settleable through chemical and biological operations through settlement via the effect of gravity. Thus, pollutants are removed from water as settleable solid substances and their transport to the other treatment units is avoided. Settlement of settleable suspended solid particles is done at the primary sedimentation tank; removal of biological coagulants formed during biological treatment is done at the final clarifier; removal of chemical coagulants formed during chemical coagulation is done at the chemical sedimentation tanks. The objective in sedimentation is to obtain wastewater whose solid particles are removed to a satisfactory extent and to obtain treatment sludge with a solid substance concentration high enough to be treated easily. Classification in sedimentation tanks could be done according to the flow types. Accordingly, the sedimentation tanks could be grouped under three categories: Horizontal and parallel flow Horizontal and radial flow Vertical and radial flow Sedimentation tanks should be equipped to satisfy uniform distribution of water and input-output structures to allow flow. Appropriate scraping unit should be present to remove scum at the surface and sludge at the bottom. The sludge chamber should be compatible with the sludge characteristics and sludge removal intervals. Floatation Article 11- Floatation enables the accumulation and scraping of liquid and solid substances in wastewater at the water surface. Floatation is realized through gas bubbles (generally air) given to the liquid medium, these bubbles attaching to the substances to be floated and moving them upwards along with themselves. In some cases, it is possible that appropriate chemical substances are added to the water for an easier floatation. Foamy floated substances at the water surface are removed through a surface scraping structure. Air bubbles used to float the particles are obtained through one of the following three methods:

4 a) Introduction of pressurized air in bubbles to the liquid under atmospheric pressure (dispersed air floatation), b) Solving air in liquid under pressure and then removing the pressure (dissolved air floatation), c) Vacuum implementation following the saturation of the liquid to air under pressure (vacuum floatation). Chemical Treatment Article 12- Chemical treatment is the general method based on using various chemical reactions to enable or accelerate the removal of solved, colloidal and suspended substances polluting wastewater. Chemical treatment aims to transform the dissolved pollutants in water to compounds with low solubility through chemical reactions or to settle colloidal and suspended particles through forming coagulants. Coagulation is generally done at the speed mixers. The time wastewater spends in these units are between minutes. As a result of the coagulation, colloids and particles formed via chemical reactions accumulate in tiny coagulants. After this stage, mixing the water slowly enables these parts formed through coagulation to more easily settleable big coagulants. Water stays in coagulation units between minutes. In order to accelerate coagulation, decrease the amount of flocculants or to increase the treatment efficiency, substances to assist coagulation (coagulant assistant) like clay, calcite, polyelectrolyte, active silica, various alkaline and acids are used. Chemical substances that are mostly used as coagulants are Al2(SO4)3, AlCl3, Fe2(SO4)3, FlCl3, CaO, Ca(OH)2, polyelectrolytes are mostly used as coagulant assistant substances. Sedimentation tanks are used to settle the flocs formed as a result of chemical coagulation. Speed mixing, slow mixing and sedimentation tanks could be separately constructed, and there are combined systems where both of them could be done together. Adsorption, disinfection and ion exchange are other physical-chemical treatment methods and they could be found in Advance Treatment Methods. Biological Treatment Systems Article 13- These are methods based on removal of organic and partially inorganic pollutants in wastewater through being used as food and energy source by microorganisms. A portion of the organic substances are transformed into microorganism cells and another portion is transformed into energy. Aerobic Processes Article 14- Aerobic processes are processes where treatment is done in oxygen rich environment. These processes are classified according to the condition of microorganisms as suspended growth, attached growth and hybrid systems where both of them are applied. There are also sequential systems where more than one process is used one after another. In suspended growth, the oxygen demand of microorganisms is met by various types of aerators. In some cases, on the other hand, oxygen could be provided biologically through algae. Active Sludge Method Article 15- It is a treatment method that organic pollution is removed by suspended microorganisms. It is based on keeping the microorganisms suspended in the mixed liquor in the active sludge tank. For this purpose, generally the use of diffusers or surface aerators is enough. Active sludge plants which could be designed as fully mixed or piston flow, wastewater moves into a sedimentation tank after the biological unit. There, biological flocs mainly composed of microorganisms whose settleability has increased are removed from water. That way, as soon as the treated water meets the needed criteria, it leaves the plant. A portion of the settled sludge is recycled back to the aeration tank so as to protect the needed concentration of microorganisms; excess sludge is disposed via sludge treatment unit. Various active

5 sludge alternatives can be used depending on the sludge age, organic load, the time wastewater spends in the system. They are mainly conventional, high speed and extended aeration active sludge systems. Nitrification and Denitrification Systems Article 16- The main objective in activated sludge plants is the removal of carbonaceous organic substances. However, the oxidation of nitrogenous substances that create BOD could also be needed. The most important nitrogenous compound is ammonia. Through nitrification, ammonia is oxidized to nitrate. In practice, nitrification could be realized in the reactor which is used to remove the carbonaceous substances, or it could be realized in a following reactor. Denitrification, on the other hand, is the degradation of nitrate to nitrogen gas without oxygen, after nitrogenous compounds are oxidized to nitrate. Stabilization Tank Systems Article 17- These treatment systems with large volume, wide area and long detention times are treatment units where wastewater is mainly naturally treated. These plants could be classified according to the characteristics of the biochemical activities realizing treatment. Mentioned activities are dependent on medium conditions like temperature, solar radiation, are also dependent on volumetric pollutant load of tanks and geometric specifications, as well. Generally, they are constructed as soil structures. These tanks are also called as lagoons. Stabilization tanks are classified as follows: Anaerobic ponds Facultative ponds Aerobic ponds Maturation ponds Anaerobic Ponds Article 18- They are used to treat wastewater which contains high organic materials and solid substance. These tanks with high volumetric organic load are typically deep soil structures, and their depth could be constructed down to 6 m in order to avoid heat loss and in order to satisfy anaerobic reaction conditions. Suspended solids in tanks are stabilized through sedimentation. The volumetric pollutant load of these tanks is around BOD 5 /m 3.day. Average detention time in anaerobic tanks is less than 5 days. Facultative Ponds Article 19- There are a surface layer where aerobic bacteria and algae are present and a bottom anaerobic layer where anaerobic bacteria are active at the bottom in facultative ponds. Between these two layers, there is a partially anaerobic medium and facultative bacteria that could adapt to both mediums. The depth of facultative ponds is around m; detention time is about 7-20 days. Detention time could be as long as 100 days, depending on the climatic conditions. Surface pollutant load is around BOD 5 /hectare/day. Aerobic Ponds Article 20- Organic substances coming to the aerobic stabilization pond are degraded by bacteria and algae. Algae produce oxygen during photosynthesis via using solar energy while making cell synthesis from inorganic food substances and carbon dioxide. Produced oxygen is used by heterotrophic bacteria. Bacteria use organic substances in wastewater as energy source. Aerobic stabilization ponds generally have low volumetric organic substance load, with a depth less than 1.5 m. that way, pond could have oxygen at all depths. Detention time is around days, surface loading rate is about kg BOD 5 /hectare.day. Maturation Ponds

6 Article 21- The objective of the maturation ponds is to improve the quality of treated wastewater, increase the efficiency of total organic substance removal of plants and to secure the bacteria removal. These types of systems may either be used after facultative or aerobic stabilization units, or after conventional biological treatment systems. Detention times of wastewater in these systems could change between 5 20 days, the surface loading rate should be less than 15 kg BOD 5 /ha.day. In maturation ponds or lagoons, feeding of various water plants and/or raising fish in these systems could increase their treatment efficiencies, and the produced plant or animal protein could also be valuated in economic means. These ponds have depths less than 1.5 m. Aerated Lagoons Article 22- Aerated lagoons, are mainly have similar characteristics to active sludge method. However, biological sludge recycling is not applied after the sedimentation tank in these lagoons. Moreover, wastewater detention times in aerated lagoons are much longer in aerated lagoons than other active sludge systems. Oxygen demand of these systems is met through externally provided synthetic oxygen besides photosynthesis reactions in the system. Organic substance per pond volume in aerated lagoons is much less than that of other activated sludge systems. A sedimentation unit takes place after aerated lagoons. The depth of these lagoons is generally about 3-5 m. If oxygen rich medium through aeration at all lagoon depths is satisfied, these lagoons are called as fully aerobic aerated lagoons. Systems where only levels closer to the surface is with oxygen, bottom parts are without oxygen are called as facultative aerated lagoons. Trickling Filter Article 23- It is the treatment method where organic waste is removed by microorganisms attached to a surface. Trickling filters are composed of stone or plastic filling material. As wastewater goes through that filter bed, the bacteria form a bio-film layer on the filling material. There are gaps between the used filling materials. Hence, microorganisms could live as a layer on the filling material, they could be fed by organic substances and air inlet is satisfied. As soon as microorganisms reach a certain thickness, they fall out of the filling material, these bio-film particles in outlet water settle down in final clarifier and they are removed from water. Sizing of trickling filters is done based on surface hydraulic rate (m3/m2/day), volumetric organic load (kg BOD 5 /m 3 /day) and recycle ratio. Sizing of trickling filters could have two types as high speed and large speed according to surface hydraulic rate and volumetric organic load. Biological Disc and Bio-cage Systems Article 24- Biological disc plants are composed of material having an appropriate surface on which bacteria can produce, which is resistant to the potential corrosive effect of the wastewater, for example plastic (like Styrofoam) in the form of disks, and on a rotating shaft or a cylindrical drum like structure full of filling material. The applicable dimensions of these disks are generally around meters. For each meter of the shaft, discs with 2 cm intervals could be places. The length of the shaft could be up to 6 m. In filled drum systems, on the other hand, sizing is generally done to reach the needed total surface area. Each of these is placed in a different cylinder reservoir, in a way to keep 45% dispersed in water. Filled Bed Reactors Article 25- Filled bed reactors, are bio-film systems containing a filling material for the attachment of microorganisms. In a typical filled bed reactor air is given through the aerators from the bottom. Activated Sludge / Trickling Filter Sequential Systems Article 26- It is possible to have multiple treatment flow schemes through combinations of various treatment methods. Therefore, activated sludge or trickling filter systems which cannot satisfy the needed treatment could be used together to obtain a certain outlet water quality. The most frequently used two treatment schemes are activated sludge tank following the trickling filter and combinations of trickling filter following activated sludge tank.

7 Anoxic Systems Article 27- Anoxic systems are different than anaerobic systems as their biochemical stages are similar to aerobic systems, but these stages being realized under non-oxygen environments. Nitrogen removal, which is realized through transformation of nitrate to nitrogen gas, is an anoxic (without oxygen) operation; this treatment could be done through suspended growth or attached growth. As soon as hydrogen sulfur formation starts in the environment, the conditions are accepted as anaerobic; hence anoxic conditions are only valid for denitrification. a) Suspended Growth Denitrification: Suspended growth denitrification is generally realized in piston flow activated sludge systems. Anaerobic bacteria provides the needed energy for growth as a result of transforming nitrate to nitrogen gas during nitrification, however, an external carbon source is needed for cell growth. As carbonaceous substances are rarely found in environments where nitrification is realized; raw wastewater (domestic), methanol or industrial wastewater which is not rich in nitrogen and phosphorus may be used as a carbon source. b) Attached Growth Denitrification: Attached growth denitrification is realized in an environment with stone or plastic filling material. Depending on the sizes of the filling material, this operation could be monitored from a sedimentation tank. Periodic backwash might be needed to prevent clogging in the filled bed. In this operation, on the other hand, an external carbon source is generally needed, as it is also needed in the attached growth denitrification. Anaerobic Systems Article 28- Anaerobic systems are operations where organic substance is degraded under anaerobic conditions, it can be composed of attached growth or suspended growth units depending on the conditions of organic substances. In these systems, organic and inorganic substances are degraded in environments without molecular oxygen. In this operation, which is mostly applied for treatment sludge and industrial wastewater with very high concentration of organic substances, organic substance is biologically degraded to methane (CH4) and carbon dioxide (CO2). Organic waste is left to be degraded in a heated (35oC-60oC) digestion tank with anaerobic microorganisms. In simple, unmixed digesters, the duration is days, system is continuously mixed. Digestion tanks are built cylindrically or in an egg-section shaped. If needed, the solid materials leaving the system could be recycled. Anaerobic Filters Article 29- They are alike trickling filters, but in anaerobic filters, input water is given from the bottom. Microorganisms grow via attaching to the filling material and on the walls. It is suitable to treat high concentration dissolved organic waste. Anaerobic filters are operated at a lower temperature than that of other anaerobic applications. Anaerobic filters could also be used to treat medium strength wastewater. Sequential Aerobic / Anoxic or Anaerobic Systems Article 30- Sequential systems are systems where more than one treatment operations are realized one after another in sequential units. Sequential aerobic/anoxic or aerobic/anaerobic systems are anaerobic, facultative systems. Sequential aerobic/anoxic or aerobic/anaerobic systems could be applied as any combination of anaerobic, facultative maturation tanks or lagoons. Nitrification denitrification applications could also be applied in sequential units. CHAPTER FOUR ADVANCED AND FINAL TREATMENT METHODS General Elements Article 31- Advanced and/or final treatment is generally, is the treatment which is applied to improve the quality of the wastewater which is the outlet of conventional biological treatment, and nitrogen and

8 phosphorus removal, filtration, adsorption, disinfection, ion exchange, ultrafiltration, reverse osmosis and chemical sedimentation methods are illustrated in here. Nitrogen Removal and then transformed into nitrate, then removed from water as nitrogen gas (N2) under anoxic conditions during denitrification. High sludge ages and low sludge loads are needed for nitrification. Phosphorus Removal Article 33- Chemical and biological methods are used separately or together to remove the phosphorus compounds in wastewater. In chemical treatment of phosphorus compounds aluminum salts or lime could be used. In this operation, phosphorus is settled as phosphate salts under high ph values. Biological phosphorus treatment happens through intake of phosphorus by microorganisms during biological treatment. Activated sludge application could remove 2-3 mg/l phosphate phosphorus from the wastewater. Another method is the utilization of chemical treatment along with the biological treatment. Shallow algae lagoons, which are intensely produced and cultivated, could also be used for advanced phosphorus treatment. Cultivated algae could also be revaluated as animal feed or as raw material in biogas production. Filtration Article 34- Sedimentation tanks following the biological and chemical treatment are units to remove suspended solid substances or colloids which could not be removed satisfactorily. In order to remove the suspended solid substances which gather in the filter bed, filter is backwashed. Filters used as a final unit in wastewater treatment may be classified according to the flow direction as downflow or upflow; according to the filter material as layered or single type material; according to hydraulic conditions, free surface or pressurized filters. Sand, gravel, granite, anthracite and similar type of filling materials are used in filters. Another filtration method, on the other hand, is to flow the water through synthetic or metal fiber sieves. Solid materials trapped could continuously be removed from these drum sieves which are called as microsieve. Adsorption Article 35- Adsorption operation is the attachment of chemical substances which create toxicity, color, odor pollution and which are hard to be treated by conventional treatment on an adsorbent solid material (adsorbent) through chemical and physical bonds. In some cases, in order to meet the outlet water quality; water outlet of biological and/or chemical treatment, could be flowed through an activated carbon medium and remaining pollutants in the water could be removed. Adsorption could also be an interim unit, depending on the conditions. Activated carbon could be used as carbon dust or granulated. In order to provide a good contact with the granulated activated carbon, wastewater is flowed upside down to an immobile colon or from the bottom to the upper side to a fluid bed reactor. In downflow colons, so as to prevent high load loss, backwash is done; in fluid bed as the bed clogging does not happen, backwash is not needed. For economical use, granulated activated carbon whose adsorption capacity is over should be regenerated. As soon as a certain level is reached at the outlet water, the colon is emptied and activated carbon is taken away for regeneration. Dust activated carbon, on the other hand, is used in a contact tank. Dust activated carbon is added to the outlet water of biological or physico-chemical treatment, carbon is left to settle down to the bottom of the tank after a certain contact time, treated water is taken away from the tank. In some special applications, dust activated carbon could also be added to the biological unit. It is not possible to regenerate does activated carbon. Disinfection Article 36- It is the operation to kill the pathogenic microorganisms. Enough contact time should be satisfied for a good disinfection.

9 Chemical materials which are used as disinfectant are chlorine and compounds; bromine, iodine, ozone, phenol and phenolic compounds, alcohols, heavy metals ad their salts, dyes, soaps and synthetic materials, quaternary ammonium compounds, hydrogen peroxide, various acids and alkalines. Among these materials, the mostly used ones are chlorine and chlorine compounds for potable water treatment and wastewater treatment. Ozone is a very effective, but expensive disinfectant. Ph 11 and ph 3 conditions are toxic to bacteria, therefore, some acids and alkalines are also effective in removing pathogenic bacteria. Wastewater should be brought back to normal ph through neutralization. Via physical methods, on the other hand, water is heated till the pasteurization point (67o C) and pathogenic bacteria which do not contain spores are mostly destroyed. Ultraviolet beams and solar light are also good disinfection tools. Ion Exchange Method Article 37- It is an advanced treatment method that is used in industrial wastewater treatment in special cases and to prepare industrial process waters. System principle is keeping the undesired anions or cations in water or wastewater in an appropriate ion exchanger of anion or cation type. Materials to enable ion exchange are: aluminum silicates, zeolite, synthetic resins and sulphonated carbonaceous materials. Lifetime of the ion exchanger depend on the amount of exchanged ion, wastewater flow and concentration of the solution to regenerate the medium. Mostly, anion and cation exchangers are used separately. Turbid water and water with colloid is disadvantageous as they decrease the resin surface. Reverse Osmosis Method Article 38- It is an advanced treatment method to provide potable water from sea water, especially in places where fresh water resources are limited, to provide reuse of wastewater and/or to obtain high quality wastewater and to secure pollution control and it is mostly used in industrial wastewater treatment. Industrial wastewater containing valuable compounds could be recycled to be used in production after reverse osmosis application. Reverse osmosis could be used in industries which need extremely pure water like electronic industry, utilization water for food and beverage industry which needs high quality water and for boiler feeding water treatment. Reverse osmosis could also be applied to the secondary treatment outlet water if reuse of municipal wastewater is considered. In reverse osmosis, two tanks are separated with a semi-permeable synthetic membrane; one of these tanks is full of fresh water and the other is full of water to be treated. Water is passed through the semipermeable membrane to the fresh water tank via applying a pressure higher than that of the osmotic pressure caused by the dissolved salts in wastewater to be treated times more pressure than the balanced osmotic pressure in reverse osmotic systems in application. This value is approximately 4000 kpa for wastewater. Ultrafiltration Method Article 39- Ultrafiltration operation is a pressurized membrane filtration method similar to reverse osmosis where semi-permeable membranes are used. Lower pressure than that of reverse osmosis is applied. Wastewater including macromolecules and colloidal substances may be treated via ultrafiltration. If the reuse or recycling of these substances is required, concentrated solid materials could be revaluated as side products. Generally, it might be used for industrial process water. Chemical Sedimentation Method Article 40- Chemical sedimentation is the operation to make the sedimentation easier via changing physical and/or chemical the condition of dissolved and suspended solid substances with the chemical material addition. Sedimentation is mainly realized by the added chemicals dragging the pollutant

10 substance or making it settleable. In some cases, the chemical material addition might lead to the increase of dissolved substance concentration in wastewater. Chemical sedimentation could be used in following cases to meet the standards in, Wastewater characteristics change seasonally, Medium treatment is needed, In order to make the settlement easier and/or to improve the settlement. Moreover, chemical sedimentation could be applied as a pre-treatment for heavy metal or toxic substance removal. Chemical sedimentation is a good solution when special phosphorus removal is needed at the outlet water depending on the receiving environment. Chemical materials used in chemical sedimentation are Al2(SO4)3, FeSO4, Ca(OH)2, FeCl3, Fe2(SO4)3 and polyelectrolytes. CHAPTER FIVE TREATMENT METHODS FOR TREATMENT SLUDGE General Elements Article 41- Solid substances which are self-settleable and which have been made settleable or floatable via biological or chemical operations are removed from wastewater by sedimentation or floatation during the treatment of wastewater. Therefore, precautions should be taken so that treatment sludge, formed by pollution separated as being concentrated, does not cause new environmental pollutions. It is possible that the sludge containing high organic content is digested anaerobically and biogas which is rich in methane (CH4) is obtained. Volumetric economic limit of digestion tanks that produce biogas is between m3. In plants where needed reactor volume is larger than 400 m3 anaerobic stabilization is used for sludge digestion, and aerobic stabilization method is applied for smaller plants. In plants larger than an equivalent population of 20 thousand with heated anaerobic sludge digestion it is appropriate that the biogas is revaluated. Additional sludge stabilization unit is not needed in aerated activated sludge systems without primary sedimentation tank which has a volumetric organic load smaller than 0.2 kg BOD 5 /m 3.day, as the sludge formed in the water treatment is not stabilized enough. During the operations applied to the treatment sludge, separated sludge water at every stage, will be recycled to the beginning of the system and as it forms an additional load to the treatment units, this situation should be considered during the sizing of the treatment plant. In regions where a lot of small treatment or primary treatment plants are present, sludge stabilization and water intake operations could be realized in central plants. However, in this case, the pollution load which will be carried by the sludge water emerging as a result of sludge water removal and the removal basics of the sludge water should be taken into consideration and necessary precaution should be taken. Sludge Thickening Article 42- Sludge thickening is applied as the solid substance concentration of settled sludge at the sedimentation tanks of treatment plants is low (0.6%-2% solid substance), in order to increase this ratio and to decrease the sludge volume. The solid substance content of the sludge is increased to 5%-12%. Sludge thickening could also be realized by dissolved air floatation systems. Especially excess activated sludge and coarse floc containing chemical sludge may be thickened more easily with floatation. Moreover, thickening centrifuges, micro-sieves or sieve drums could be used for mechanical thickening. Sludge Stabilization

11 Article 43- Thickened sludge stabilization is realized by chemical substance addition, biological stabilization, on the other hand, is realized by anaerobic or aerobic stabilization or composting. These methods are briefly described below: a) Anaerobic sludge stabilization: Following sludge digester tanks could be used for this purpose. -Basic digester tanks: Generally mixing or heating is not applied and the amount of solid substance in the digesting sludge. -Heated and mixed sludge digester tanks: Solid substance amount of sludge coming from sludge thickening or final digester compartment is checked and that way sludge load and concentration and temperature can be kept under controlled. At least 90% of the technically foreseen gasification should be realized while sizing the digester tanks. Anaerobic digestion operation is very much sensitive to temperature, ph changes and toxic substances. Especially toxic substance control should be done strictly at the treatment plants where sludge digestion takes place. Pre-treatment should be applied to wastewater containing toxic substances; amount of toxic substances should be kept less than the values given in Table 1 in treatment sludge to be stabilized anaerobically. Gas storage tank should be built according to the obtained biogas usage out of sludge digestion plants. Storage volume should at least be enough to store 25% of the daily produced gas. If the biogas is only used in gas motors of the compressors and pumps of the treatment plant, weekly balance should be done. Necessary precautions should be taken against gas leaks and explosions where biogas is formed, transferred and stored. b) Aerobic sludge stabilization: Aerobic sludge stabilization plants are more tolerant to toxic substances and shock feeding conditions than anaerobic systems. Dewatering and thickening operations of aerobically stabilized sludge is generally easier and more efficient. Temperature, biochemical oxygen demand and mixing are determinant in the identification of stabilization time and efficiency. Detention time is shortened and thermal disinfection can be realized in thermophilic aerobic systems operated at a temperature higher than 45 o C. If the stabilization will be along with the primary sedimentation tank sludge, enough precautions should be taken for the odor problem. c) Composting: Composting is a natural aerobic stabilization application which is done with the organic substances with a water content of 50-60%. When fresh or digested treatment sludge, is mixed with substances with high organic content like sawdust, hay, domestic solid waste, made porous and less watered, aerated, it is digested in a thermophilic way and stabilized. Sludge Dewatering Operations Article 44- Dewatering is done through natural or mechanical methods. These methods are listed below: a) Natural dewatering methods: Only the treatment sludge stabilized aerobically, anaerobically or chemically may be given to the natural dewatering beds. Treatment sludge which is not stabilized is not given to drying beds and sludge lagoons due to their extensive odor effects. Natural dewatering is the operation of watered sludge losing the water through drainage in sand layer and partially via evaporation given onto the gravel and sand bed as a layer of 20 cm. dewatering operation s completed within days and the sludge cake formed as a result of this duration is removed via shovel or machines. The same area is reused. Sludge load varies between kg KM/m2/year according to the climatic and seasonal conditions in natural dewatering beds. Sludge lagoons may also be used for dewatering. In sludge lagoons removal with shovel is not done, operation continues until the lagoon is full. As soon as it is full, the lagoon is abandoned or sludge cake is emptied and removed to another place.

12 b) Mechanical dewatering methods: Mechanical dewatering methods may be applied instead of natural dewatering methods due to odor problem and excess area need. In mechanical dewatering methods; Centrifuges Filter press Belt filter (Band filter) Bag filter units are used. Sludge characteristics, sludge type, target solid substance concentration, plant capacity, type and amount of sludge conditioning materials used are effective in method selection. Parameters needed to determine the capacity of the mechanical dewatering units are obtained experimentally with the assistance of pilot plants and laboratory trials. For this purpose, average values obtained as a result of various applications and given in Table 2 could be used. CHAPTER SIX DETERMINATION OF DILUTIONS IN DEEP SEA DISCHARGES General Elements Article 45- Wastewater is first sprayed to the sea from the final pump in the coast or from the holes in diffuser via the energy resulting from the gradient in the final part of the sewage system to the sea while mixing with the sea. The first phase, which is called as the primary dilution happens due to the energy wastewater carries and due to the movement of the wastewater in the sea as a result of the density difference and it ends when all of the kinetic and potential energy wastewater initially has, is transferred to the receiving environment. Wastewater cloud which is formed by the sea water mixture that way is left to the natural movements of the sea environment. It is possible that the wastewater cloud is buried in a layer along the sea bottom or depth, or it may come up to the surface where the depth is insufficient or under special marine circumstances. The movement of the wastewater cloud is relevant to the flows at the depth where wastewater is found. In a still and motionless sea, the cloud takes the point where it emerged as a center and from there it is spread and diluted very slowly. Wastewater clouds buried in at the bottom parts of the sea may move away to different sides with respect to observations at the surface via the flows at that depth. The wastewater cloud being mixed to the sea water and being diluted during the enlargement and moving away is called as secondary dilution. It is necessary that the pollution parameters of the wastewater discharged to the sea should be compatible with the criteria in Table 22 given in the 34 th article of Water Pollution Control Directive. Wastewater should be compatible with the characteristics of the marine environment given in the Table 23 and 4 of the annex of Water Pollution Control Directive, after the wastewater is discharged to the sea. Moreover, the limitations in the Declaration on Harmful and Hazardous Substances in Water should be obeyed to during deep sea discharge. Bacteriological quality of the sea water is satisfied via keeping the total or fecal coliform group organisms, which are used as indicator organisms, under a certain concentration in deep sea discharge projects. The decrease of these types of pollutants starting from the time of sea discharge to the time when it reaches to the region planned to be protected with the project, for instance a beach, is called as the third dilution. The third dilution is only valid for pollutant parameters which change characteristics through physical, chemical and biochemical reactions in marine environment. The first, second and third dilutions explained above totally define the dilution capacity of the deep sea discharge system of the pollutants contained in wastewater given to the receiving environment. The first dilution should be around 100 with the deep sea discharge project according to the article 35 of the Water Pollution Control Directive, however, engineering precautions should be taken so that it is not smaller than 40 under no circumstances. CHAPTER SEVEN USING TREATED WASTEWATER IN IRRIGATION Using Treated Wastewater in Irrigation

13 Article 46- The most important parameters to be inspected in order to determine the compatibility of wastewater to be given to the land and for irrigation are as follows: -Total concentration of dissolved material in the water and electrical conductivity, -Concentration of sodium ion concentration and the ratio of sodium ion concentration to the other cations, -Concentration of Boron, heavy metal and potentially toxic other materials, -Total concentration of Ca++ and Mg++ ions in some cases, -Total solid substance, organic substance load and amount of floating substances like oil and grease, -Amount of pathogenic organisms. Dissolved salts in wastewater, boron, heavy metal and similar toxic materials may stay in the environment, be taken by the vegetation or stay in water depending on the climatic conditions of the region, physical, chemical and biological characteristics of the soil. Thus, the soil characteristics of the region is also considered along with the compatibility of the water to the limit values foreseen with respect to physical, chemical and biological parameters if the wastewater is to be used in land and disposal. Total concentration of dissolved salts in irrigation water may easily be detected via the electrical conductivity (EC) value. The coefficient (M) of the ratio between the total salt concentration and electrical conductivity may be used continuously once it is detected as a result of experimental studies. This coefficient is between when expressed through conductivities (micromhos) and salt concentrations (mg/l) at 25oC. The sodium in wastewater being kept in the irrigated soil is defined as Sodium Adsorption Rate (SAR). SAR ratio is used as a measure of harmfulness of water with respect to sodium (or similar alkalines). The sodium adsorption rate is detected with the following equation; SAR= Na+/((Ca+++ Mg++)/2)1/2 There, Na+, Ca++, Mg++, are liquid concentrations with miliequivalent grams (Meq/1). Classification of irrigation water according to the electrical conductivity and sodium adsorption rate (SAR) is done according to the diagram in Figure 1. It is possible to find the wastewater class with the assistance of this diagram between irrigation water classes C1S1 - C4S4. Irrigation water quality criteria required in agricultural irrigation is given in Table 4. Concentrations of maximum heavy metal and toxic elements that may be permitted in irrigation water are summarized in Table 5. If any substance has a concentration of Co min soil as mg/kg, the total value of this substance may be detected as kg/ha by (4.2 * Co) expression in the irrigated soil. Maximum total amounts that could be given to the unit area illustrated in the first column of Table 5 could only be used after (4.2 *Co) finding out the calculated current amount in soil. Example: The boron concentration in soil is Co= 80 mg/kg and the acceptable maximum concentration for boron is 680 kg/ha; 4.2*Co=336 kg/ha. Accordingly, maximum = 344 kg/ha boron could be added to unit area through irrigation could be permitted. Elements and technical limitations on wastewater usage in irrigation are illustrated in Table 6, conditions to use wastewater formed in various industries as irrigation water are given in Table 7 and the condition of using or not using the treated domestic wastewater without disinfection is given in Table 8. Boron Problem in Irrigation Water Article 47- Due to the significance of boron element in some region in our country, in addition to the classifications above, another wastewater-irrigation water classification is needed to consider the resistance of plants to boron.

14 In fact, all plants need a little amount of boron for their normal growth. However, boron has a very narrow limit between the needed amount by plants and the toxicity amount and this limit changes with respect to plant types. Having boron concentrations in soil or irrigation water above these limits causes paling, burns and cleaving in plant leaves, shedding in immature leaves and decrease in growth rate and efficiency. Irrigation water is classified according to the resistance level of plants to boron in Table 9. This classification should be considered while using treated wastewater in irrigation. CHAPTER EIGHT EFFECTIVE DATE, LAW ENFORCEMENT Effective Date Article 48- This declaration becomes effective on its issue date. Law Enforcement Article 49- Ministry of Government to whom the General Directorate of Environmental Protection under the Prime Ministry is tied to (*) executes the clauses of this declaration. * In the clause of Establishment and Tasks of Ministry of Environment, Law No. 443 and the Provisional 1 st article of decree is changed as Minister of Environment.