WASTEWATER TREATMENT. Lili sugiyarto

Transcription

1 WASTEWATER TREATMENT Lili sugiyarto

2 The primary goal The removal and degradation of organic matter under controlled condition

3 Three major steps Primary treatment Secondary treatment Tertiary treatment

4 Primary treatment A physical process that involves the separation of large debries, followed by sedimentation Comprises grit tank and settling tank Settling tank also known as sedimentation tank (sand and gravel)/clarifier About half suspended organic solids settle to the bottom as sludge or biosolids (primary sludge)

5 Secondary treatment Consist of biological degradation (decomposed and the number of pathogens is reduced) The effluent from primary treatment may be pumped into a tricklingfilter bed ( an aeration tank/a sewage lagoon Disinfection step is generally included at the end of treatment

6 Large-scale wastewater treatment

7 Trickling filter bed Rocks provide a matrix supporting the growth of a microbial biofilm that actively degrades the organic material under aerobic conditions Effluen from primary treatment is pumped into a tank and mixed with bacteria-rich known as activated sludge air and pure oxygen pumped through the mixture promotes bacterial growth and decomposition of the organic material

8 Then goes to a secondary settling tank Water siphon off the top of the tank Sludge is removed from the bottom Some of the sludge is used as an inoculum for the incoming activated sludge The sludge that is not return as secondary sludge

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12 Trickling filters Gram negative bacteria : Zooglea, Pseudomonas, Alcaligenes, Achromobacter, Flavobacterium Gram positive : Corynebacterium, etc Fungi : Fusarium, Trisporon, Ascoidea

13 In secondary treatment It contains a high level of the organic nutrients phosphate and nitrate Nitrosomonas : oxidize ammonia to nitrite Nitrobacter : oxidize nitrite to nitrate

14 Secondary treatment Aerobic digestion tank Anaerobic digestion tank

15 Anaerobic digestion tank The degradatif and fermentative process divided into 2 stages : acid forming and methane forming Genera of Methane forming stage : Methanobacterium, Methanosarcina, Methanococcus (convert acetate, hydrogen and CO2 to methane)

16 The major metabolic stages Complex organic compounds (polysaccharides, fats, protein) Hydrolisis Hydrolysis by extracellular bacterial enzymes Monomeric compounds (sugar, fatty acids, amino acids) Higher organic acids Acetic acid, H2, CO2 CH4 Acidogenesis methanogenesis Acetogenesis

17 Types of Bioremediation In situ bioremediation Composting Landfarming Above-ground bioreactors

18 Activated sludge process

19 Activated sludge flocs Note filamentous bacteria Note Vorticella and other protozoa

20 Activated sludge model L 0 L L L L L

21 Composition of sludge PK, page 21 Urban Water Systems Predominantly water Micro-organisms Viruses, pathogens, germs in general Organic particles, heavily bio-degradable Organic compounds, inert, adsorpted to sludge flocs Heavy metals Micro-pollutants, pharmaceuticals, endocrine disrupters All non-degraded compounds extracted from wastewater are found in the sludge 12 Sludge treatment

22 Activated sludge plants Hyperion, Playa del Rey, CA)

23 Primary aeration tank

24 Tertiary treatment Involve some type of physicochemical treatment such as coagulation, filtration, activated carbon adsorbtion of organics and additional disinfectan

25 PK, Goals of sludge treatment page 25 Urban Water Systems Volume reduction Thickening Dewatering Elimination of pathogenic germs If used in agriculture as fertiliser or compost Stabilisation of organic substances Gas production Reduction of dry content Improvement of dewatering Reduction of odour Recycling of substances Nutrients, fertiliser Humus Biogas 12 Sludge treatment

26 Process water Overview PK, page 26 Wastewater treatment Urban Water Systems Primary, secondary, tertiary sludge Thickening Energy Hygienisation Gujer (1999) Stabilisation Thickening Dewatering Drying Incineration Biogas Agriculture Disposal site Construction industry 12 Sludge treatment Atmosphere

27 Oxygenated systems Cryogenic air separation facility, Hyperion, Playa del Rey, CA)

28 Typical steps in modern wastewater treatment

29 Flotation unit PK, page 29 Urban Water Systems 12 Sludge treatment

30 Examples of naturally transmissible catabolic plasmids Primary substrate Plasmid Size (kb) Host Toluene pww0 (TOL) 117 Pseudomonas putida mt-2 Alkylbenzene sulfonate ASL 91.5 Pseudomonas testosroni octane OCT ~500 P.oleovorans Naphthalene Nah7 83 P. Putida PpG7

31 Pseudomonas putida mt-2 Chromosomal gene encode ortho pathway : acetyl CoA and succinate TOL plasmid encodes meta pathway : acetaldehide and pyruvic acid

32 TOL (pww0) plasmid The genes encoding catabolic enzymes : xyl genes The Xyl genes : xyl ABC (upper) and xyl XYZLEGFJKIH (lower/meta)

33 Xyl ABC Encode degradation toluene and xylene to benzoate and metylbenzoates

34 Xyl XYZLEGFJKIH Encodes degradation of benzoate and methylbenzoate to acetaldehyde and pyruvat