Kağıt endüstrisi atıksularının havasız biyolojik arıtımı üzerine bir araştırma

Abstract

Bu çalışmada yüksek kirlilik yüküne sahip kağıt endüstrisi atık sularının anaerobik arıtılabilirliği incelenmiştir. Bunun için seçilen arıtma tesisine ait bir yıllık deneysel çalışma verileri değerlendirilmiştir. Birinci bölümde, çalışmanın anlamı, önemi, amaç ve kapsamı kısaca özetlenmiştir. İkinci bölümde, kağıt hamuru ve kağıt endüstrisinin dünyadaki ve ülkemizdeki durumu, kağıt ve kağıt hamuru üretim şekilleri, endüstri atıksularının özellikleri ve atıksuların arıtılması konuları hakkında bilgi verilmiştir. Üçüncü bölümde, havasız arıtmanın genel prensipleri olan asit ve metan üretimi açıklanarak, havasız arıtmanın teknolojik şartları belirtilmiştir. Dördüncü bölümde, havasız arıtmanın havalı arıtma ile karşılaştırılması yapılmış ve havasız arıtma sistemleri kısaca özetlenmiştir. Beşinci bölümde, atık kağıttları kağıt üretimi ile ilgili bilgi verilerek incelenen tesisin üretim ve arıtma sistemlerinin özellikleri açıklanmıştır. Altıncı bölümde, incelenen tesisin işletme verileri tablolar ve şekiller ile izah edilerek kinetik değerlendirme yapılmıştır. Yedinci bölümde ise tesisin işletme verileri değerlendirilerek elde edilen sonuçlar özetlenmiştir. viii

Most agro industries, processing complex natural organics, generate strong wastes. Anaerobic digestion has been considered as a promising method for these industrial vvaste waters. Anaerobic treatment is the biological process in the absence of oxygen for the stabilization of organic matters by conversion to methane and inorganic end products such as carbondioxide and Ammonia. Anaerobic digestion as a vvaste water treatment and energy production method looks extremely attractive for developing countries, because it pairs a number of significant advantages such as high COD removal, low energy cost and low amounts of excess biological sludge production. The objective of the anaerobic treatment of vvaste vvaters that is produced by pulp and paper industry for this purpose a selected refining unit's data has been examined for a period of öne year. As a result of this study the COD removal yield of the vvaste vvater of anaerobic vvater was varying between 80-85%. MILL DESCRIPTION VVith this study a factory that produces recycled paper from vvaste paper and strawwas examined. Recycled paper production has lots of benefits not only environmental wise but in production processes also. During these processes to prepare the raw material from vvaste papers are easier and cheaper then cellulose production. ix Besides the disadvantages in the produced material is a short fibered material, comparing the cellulose, and as a result of this recycled paper production is limited with wrap papers, boxes, nevvspaper and cleaning towels. Recycled paper production can be done by 1. Simple methods 2. Segregate the silk methods which is a complex method. Simple methods can only be used if the vvastepaper's are classified and distinguished properly. in these methods vvastepapers are used to produce dough and mixing with cellulose they get ready for the process. in the complex method vvastepapers are applied thaw detergents, dispersants and strong alchaline solutions so that the pigments and the artificial matters in ink may segregate. The dough that is on hand after ali are filtered and mixed with cellulose and goes with production process. The factory produces recycled paper out of vvastepaper and straw. Products are testliner vvhich is produced out of vvastepaper, and stravv-fluting out of stravv. The ratio of stravv varies betvveen 25-40% accordşng to the type that produced. Annual capacity of the factory is 90.000 tons vvhere 20.000 of it is testliner and the rest is stravv-fluting. WASTEWATER TREATMENT PLANT The examined refining unit was established Jun.'87. The plant consists of a black liqueur and vvhite liqueur basin, anaerobic reactor and activated sludge unit. For anaerobic refining tank with feed-back mechanism and fully mixed 10.000m3 volumed is used. System operates at mesophiilic conditions about 35-37°C temp. the pH degree in around 7.3. System is fed by wastewater vvith a flovv rate of 1750m3 per day; and the organic loading is aprox. 2kg. per day. Input vvater's average values of the refining unit is given at Tablo 1. X Parameters influent Flow (m3 / day ) 1750 Temp. °C 37 pJH 7.3 Organic loading (kg.KOl/m3 day) 2 COP (kg/m3) 12 COP removal (%) | 80 TABLO 1. Parameters for the treatment system MATERİAL AND METHOD in this part flovvrate, heat, pH, total volatile suspended solids, suspended solids and COD values and their differantials versus time has been calculated över the datas of the unit which chosen to prove the possibility of refining paper industries wastewater with no air involving in. Besides vapor, biogas and CH4 productions were calculated for the feeded COD values. Fiğ. 1 shows the relation betvveen COD removal and expected production of Methane. At the end administrating data öne examined by kinetics modelling. RESULTS AND DISCUSSION While keep the temperature of anaerobic reactor around 37°C, wastewater with a pH of 7.3 and with an average of 12 kg/m3 input COD will be measured 2.5 kg/m3 output COD. Expected biogas production varies 2.000- 14.000 m3 per day. CH4 production varies 1500-9000 m3 per day, vapor production varies 20.000-100.000 m3 per day. in correleation with COD removal total volatile suspended solids don't vary since the reactor is a complete mixture operated öne. Suspended solid removal is around 50%. Monod's and the linearised second order substrate removal kinetics were applied to the experimental data, but only the second degree model fitted. Usually; -*£- = b.e+a s0-se expression is valid for this type. VVhere a =.8, b = 1.02 is founded at the end. Fiğ. 2 gives an idea of administrative data applied to kinetics modelling. xi 9000 , ~ 8000 / m 7000 ^~s.6 eooo ^---~^ ^ 5000 E 4000 ___- -' ~ 3000 ^ -^ Z 2000 ^/-x ^ 1000 o<-coırîr-OGîr«».CDinoo^-^cD'-;'3;r>ococNi«q^r-: cTİ^ıdr^oödOTaimddr-'r^^rşicNCNro^^^^iE" COD { kg / m3) FIG. 1 Relationship between COD removal and expected production Methane ısı -a-- 12 ^ */ 10 w+-mf*m "f8' ->^ m ° JKC w - J» 4 //^ /)_ x^ J.« !/_ _ -. oJ . . ,-l-. , . 1 O 2 4 6 8 10 12 14 16 0 (day) FIG. 2 Administrative data applied to kinetics modelling. xii RECOMMENDATIONS The purification process of paper industry's wastewater in established units is the main topic of this thesis. Besides yearly data of fully mixture, anaerobic feedback reactors is evaluated in this study. According to this evaluation, wastewater has a value of 1000-2000 m3/day as the input flow rate and the temperature which is one of the most important parameter that effects anaerobic purification process is between 30-45°C. Inner temperature of the reactor is kept at a constant of 37°C which is the optimal value with an assistance of a heat regulator. The pH values of the input water for white liqueur is 7.03-7.55, for black liqueur is 6.01-6.9 and inside the reactor is varying 7.2-7.45; that shows us the consistency of anaerobic purification process. Two type of wastewater with different characteristics were submitted to the anaerobic reactor, therefore input KOI values are calculated as approximated weekly values. According to this calculation the total KOI value of the input water is about 11000mg/lt. The output value of KOI is about 1500mg/lt. which means the yield of the reactor is around 80%. Approximately 70% of the total non-soluble matter at the entry level of the reactor is organically decomposable. In addition to this only 10% of this amount is volatile matter. Therefore while calculating the biochemical mass in the reactor the non volatile amount that is 90% should be subtracted as a result of high Lygnin in the input wastewater. The average age of mud (6C) is about 37 days and hydraulic awaiting time (9) is 6.9 days in an anaerobic reactor. In order to calculate the yield of the purification process, the percentage of CH4 and the flow of bio-gas should be carefully traced. In this study bio-gas, CH4 and reduced vapor flows are calculated according to the following equations. 1kg. KOI = 0.395m3 bio-gas ; 1m3 bio-gas = 0.65m3 CH4; 7.6kg. vapor = 1 m3 bio-gas. More the concentration of reduced KOI increases, it is expected that vapor production increases accordingly. This expectation is proven during the calculations of this study. In order to establish a model to specify the anaerobic purification of the wastewater, of the purification unit mathematically; during the data reduction mainly Monod's model and then Second Degree Kinetics model were used. The Monod Kinetics Constants were: Y = 0.017, K> = 0.02, K = 1.06, FQ = 6570. Unfortunately because of the insufficient data found, we are unable to tell this method is the right one for the process. Data were more suitable to Xlll the Second Degree Kinetics. The reactor's being an full mixture one has a major role in this result. The kinetics constants found in this method are: b = 1.02, a = 0.8. Based on these constants the output KOI values were calculated in lieu of HRT. These calculated KOI values are in good correlation with the practiced factory's output data of KOI values. Under the guidance of this study, following results were achieved about anaerobic treatability of pulp and paper industries wastewater.. The bioligically hard-to-compose matter should be seperated.. The inert KOI level at the input level should be calculated.. The effect of micro-biological products in the output KOİ values may be examined.. In order to end up with definite results all the measurements shoul be carefully traced.. The sieves at the entry of the unit should be refined.. The increase on the yield of an anaerobic reactor could be a subject of another thesis. XIV