625102712-Microbiological-Treatment-of-Liquid-Sources-U2.pptx

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1. Microbiological Treatment of liquid sources

2. Liquid Waste . Liquid waste is defined as any waste in liquid form. The term wastewater is referred to the water which is discarded after primary use, or which is worthless, defective and of no use.

3. Liquid Waste . Contaminated wastewater is the cause of any number of serious environmental problems . Biological methods for wastewater treatment were developed during the middle of the 20th century, as attention focussed on the effects of oxygen-consuming organisms on lakes, rivers and seas.

4. FROM RESIDENTIAL AREAS In urban areas, the liquid wastes from residential areas are often referred to as domestic wastewaters . These wastewaters come from our day-to-day living and include those from food preparation, washing, bathing and toilet usage.

5. WHAT IS THE DIFFERENCE? Blackwater is wastewater that contains human excreta (feces and/or urine). Greywater is wastewater from activities such as washing and food preparation and does not contain excreta. Sullage is another name for greywater .

6. DISPOSAL Blackwater and greywater are produced from domestic dwellings with access to a piped water supply and also from business premises and the various institutions, such as schools and health centres , found in residential areas. The term  sewage  is used to describe a combination of all these types of liquid waste, frequently also with surface run-off.

7. SEWAGE Sewage is collected in underground  sewers  that carry the effluents to a sewage treatment plant. Then is cleaned by various physical and biological processes before being discharged into a river or lake. It may be possible to reuse the treated water, typically for irrigation. 

8. FROM COMMERCIAL AREAS Commercial areas: comprising business establishments, shops, open market places, restaurants and cafes – will mostly resemble wastewaters from households.

9. FROM COMMERCIAL AREAS This is because only human-related activities are undertaken in such areas, as opposed to other activities such as industrial production. Effluent from restaurants and cafes contain high levels of cooking oil this can be overcome by using a  grease trap.

10. FROM COMMERCIAL AREAS

11. GREASE TRAP A grease trap consists of a small tank or chamber which slows the speed of effluent flow. In the grease trap, fats, oils and grease float to the top of the wastewater and form a layer of scum that is contained within the tank. This can then be removed and disposed of as solid waste. Relatively clean water exits from the grease trap for disposal.

12. FROM INDUSTRIAL AREAS liquid wastes are generated by processing or manufacturing industries and service industries , such as car repair shops. The type of industry determines the composition of the waste.

13. FROM INDUSTRIAL AREAS The wastewaters from facilities that make food products will not be harmful to humans, but those from other industries may contain a variety of chemical compounds , some of which may be hazardous (and therefore potentially harmful).

14. FROM INDUSTRIAL AREAS Industrial wastewaters which contain hazardous substances must be treated , and the substances removed before the wastewater is discharged to the environment . Another difference is that the flow rate can vary dramatically in some industries, for example, where production rates vary with the season, such as in the processing of certain food crops .

15. STORMWATER Stormwater can be contaminated with many different types of pollutant such as faecal matter, soil, rubber from vehicle tire wear, litter, and oil from vehicles.  Stormwater may be channelled into the sewers, or it may flow into open ditches.

16. CHARACTERISTICS LIQUID WASTES Liquid wastes can be described according to their physical, chemical, and biological characteristics.

17. PHYSICAL CHARACTERISTICS SOLIDS May contain particles of solid material carried along in the flow. These may be settleable solids or suspended solids.

18. Settleable solids They sink to the bottom (settle out) when the speed of flow is reduced, for example, when the wastewater is stored in a tank.

19. Suspended solids   Are small particles that remain in suspension in the water ; they do not dissolve in the wastewater but are carried along in it. 

20. Temperature   Wastewaters are generally warmer than the ambient temperature. Warm or hot water may be included in the waste stream from domestic activities such as showering or from industrial processing.

21. Odor Wastewaters can have an odour , usually due to generation of gases as a result of biodegradation in the wastewater.  Organic  matter is any substance that is derived from living organisms, such as human and animal wastes, food waste, paper and agricultural wastes. Detecting odour tends to be a subjective process but it is possible to measure it in terms of odour units.

22. Chemical characteristics Wastewaters from many different sources contain organic matter, which is a frequent cause of pollution in surface waters.

23. Biochemical Oxygen Demand If organic matter is released into a river or lake, bacteria and other micro-organisms that are naturally present in fresh water will degrade the waste and in the process they use dissolved oxygen from the water. If there is a lot of organic matter, then most or all of the dissolved oxygen may be used up, thus depriving other life forms in the water of this essential element.

24. The oxygen taken up in degrading the organic matter is referred to as its  oxygen demand. This can be determined by a measure called the  biochemical oxygen   demand (BOD).  BOD tests are carried out in a laboratory and involve measuring the amount of oxygen used, usually over a period of five days, as the organic matter in the wastewater breaks down. The result is expressed in mg/l.

25. Chemical Oxygen Demand There is also a chemical method of determining the quantity of organic matter called the  chemical oxygen demand (COD)  test. This test is much quicker than the BOD test, taking only about two hours to carry out. It depends on chemical oxidation of the organic matter rather than biological degradation. It involves boiling a sample of wastewater with a mixture of concentrated acids and a measured quantity of oxidising agent to oxidise the organic matter. 

26. Inorganic material Wastewater also contains  inorganic  chemicals. This means any substance that has not come from animals or plants, so it includes a wide range of different chemicals as well as inert solids like sand and silt. 

27. Inorganic material Many inorganic chemicals are dissolved in the water and although some are harmless , others are pollutants that can damage aquatic life such as fish and other organisms that live in water. One example is ammonia (NH 3 ) which is present in human and animal excreta. Like organic matter, ammonia is broken down in the environment by natural processes.

28. Inorganic material

29. Chemical Oxygen Demand Represents the quantity of oxygen required to chemicaly stabilise the carbonaceous organic matter . Uses Strong oxidising agents under acidic conditions . The test generates results in two hours .

30. CHEMICAL PROPERTIES Nitrogen Phosphorus pH Alkalinity Chlorides Oils and Greases

31. TOTAL NITROGEN Includes organic Nitrogen , Ammonia , Nitrite and Nitrate . It is an essential nutrient for microorganisms growth in biological wastewater treatment . Organic nitrogen and ammonia together are called TOTAL KJELDAHL NITROGEN TKN.

32. TOTAL NITROGEN Organic Nitrogen - Nitrogen in form of proteins , aminoacids and urea. Ammonia – Produced in the first stage of the decomposition of organic nitrogen . Nitrite – Intermediate stage in the oxidation of ammonia . Practically absent in raw sewage . Nitrate – Final product in the oxidation of ammonia . Practically absent in raw sewage .

33. TOTAL PHOSPHORUS Exists in organic and inorganic forms . It is an essential nutrient in biological wastewater treatment . Organic phosphorus – combined with organic matter . Inorganic phosphorus – Orthophosphates and polyphosphates .

34. pH Indicator of the acidic or alkaline conditions of the wastewater . A solution is neutral at pH7. Biological oxidation processes normally to tend to reduce the pH.

35. Alkalinity Indicator of the buffer capacity of the medium ( resistante to variations in pH). Caused by the presence of bicarbonate , carbonate and hydroxil ions .

36. Chlorides Originating from drinking water and human and industrial wastes . Salt Magnesium chloride Aluminum trichloride Tethra chlorosilane Phosphorus pentachloride

37. Oils and Greases Fraction of organic matter which is soluble in hexane . In domestic sewage , the sources are oils and fats used in food .

38. Treatment levels Wastewater Treatment Systems

39. What we need ? Environmental impact studies on the receiving body . Treatment objectives . Treatment level and removal efficiencies .

40. ENVIRONMENTAL IMPACT Are necessary for the evaluation of the compliance with the receiving body standards . The requirements to be reached for the effluent are also a function of the specific legislation that defines the quality standards .

41. DESIRED QUALITY Qualities and standards are associated with the concepts treatment level and treatment efficiency .

42. WASTEWATER TREATMENT Is usually classified according to the following levels : PRELIMINARY PRIMARY

43. PRELIMINARY TREATMENT Its objective is only the removal of coarse solids .

44. PRIMARY TREATMENT Aims to remove : Settleable suspended solids . Particulate (suspended) BOD ( associated to the organic matter component of the settleable suspended solids .

45. SECONDARY TREATMENT Aims to remove : Particulate (suspended) BOD ( associated to the particulate organic matter present in raw sewage , or to the non settleable particulate organic matter , not removed in the possibly existing primary treatment . Soluble BOD ( organic matter in form of disolved solids ).

46. TERCIARY TREATMENT Aims to remove : Nutrients Pathogenic organisms Non-biodegradable compounds Metals Inorganic Dissolved solids Remaining suspended solids

47. TERCIARY TREATMENT As we saw , this treatment is for removal of specifica pollutants , ( usually toxic or non-biodegradable compounds ) or the complementary removal of pollutants that were not sufficiently removed in the secondary treatment . This treatment is very rare in developed countries .

48. Activated Sludge Process

49. Screens - Removes big particles. Grit removal - S and and similar heavy particles are removed. Primary Clarifier - Smaller solids are removed in a  settling  or  sedimentation  tank. In this unit, the  wastewater  spends more time (about one hour) to allow for a good separation Aeration section - Aeration is provided either by mechanical surface agitators or by submerged diffusers of compressed air ( WSP  2008). Aeration provides oxygen to the  activated sludge  and at the same time thoroughly mixes the  sludge  and the  wastewater (UNEP & MURDOCH 2004). During aeration and mixing, the  bacteria  form small clusters or  flocs (TILLEY et al. 2008). Under these conditions, the  bacteria  in the  activated sludge  degrade the organic  substances in the  wastewater . They use the  organic  substance for  energy , growth and reproduction. The end  products  are carbon dioxide (CO2), water (H2O) and new cells. Final Clarifier - The sludge is settled while the clean water is discharged to the receiving stream UltraViolet Desinfectation - UV disinfects water containing bacteria and viruses and can be effective against protozoans like,  Giardia lamblia cysts or Cryptosporidium oocysts . Activated Sludge Process

50. Anaerobic digestion is a process in which microorganisms break down biodegradable material in the absence of oxygen. It can be used to process a wide range of organic material, from food waste and grass to waste paper and animal waste. The process produces biogas — primarily methane (CH 4 ) and carbon dioxide (CO 2 ) — that can be converted into electrical and thermal energy. The anaerobic breakdown of organic matter is a three-stage process. During the transformation of the organic matter, intermediate compounds known as metabolites are formed. Anaerobic Wastewater Treatment

51. primary sludge or very concentrated waste such as animal manure or wastewater from slaughterhouses Anaerobic Wastewater Treatment

52. wastewater polluted by soluble organic substances, such as those from industrial processors including breweries, sugar refineries, and candied fruit manufacturers. Anaerobic Wastewater Treatment

53. Anaerobic Wastewater Treatment

54. SLOW SAND FILTERS

55. SLOW SAND FILTERS The basic principle of the process is very simple. Contaminated freshwater flows through a layer of sand , where it not only gets physically filtered but biologically treated . Hereby, both sediments and pathogens are removed . This process is based on the ability of organisms to remove pathogens. The top layers of the sand become biologically active by the establishment of a microbial community on the top layer of the sand substrate, also referred to as ‘ schmutzdecke ’

56. SLOW SAND FILTERS As the process of biological filtration requires a fair amount of time in order to purify the water sufficiently , SSFs usually operate at slow flow rates between 0.1 – 0.3 m 3 /h per square metre of surface . The water thus remains in the space above the medium for several hours and larger particles are allowed to separate and settle.

57. SLOW SAND FILTERS Slow sand filtration is an extremely efficient method for removing microbial contamination and will usually have no indicator bacteria present at the outlet. SSFs are also effective in removing protozoa and viruses. 90 to 99% reduction in bacteria and viruses is achieved

58. Yet, slow sand filtration is generally not effective for the majority of chemicals. However, it can be argued that chemical standards for drinking water are of secondary concern in water supply subject to severe bacterial contamination 

59. RAPID SAND FILTERS

60. RAPID SAND FILTERS Rapid sand filtration is a highly effective method to remove turbidity if it is correctly applied . Equally, solids formed during pre-treatment, i.e. coagulation-flocculation, are filtered. A well-operated RSF reduces turbidity to less than 1 NTU ( Nephelometric Turbidity Unit ) and often less than 0.1 NTU . Regarding the removal of most other contaminants, the RSFs are ineffective . If combined with adequate pre-treatment measures and final disinfection, rapid sand filtration usually produces safe drinking water. Turbidity  is a measure of the degree to which the water loses its transparency due to the presence of suspended particulates. 

61. RAPID SAND FILTERS Rapid sand filtration, in contrast to slow sand filtration, is a purely physical treatment process. As the water flows through several layers of coarse-grained sand and gravel, relatively large particles are held back safely. However, RSFs never provide safe drinking water without adequate pre-treatment and final disinfection. Usually, coagulation and Flocculation   and chlorination  are applied for that purpose.

62. This filtering process is determined by two basic physical principles . First, relatively large suspended particles get stuck between the sand grains as they pass the filter medium (mechanical straining). Second, smaller particles adhere to the surface of the sand grains caused by the effect of the van der Waals forces (physical adsorption). A chemical filter-aid (i.e. coagulant or flocculant) might be added to promote additional adhesion. RAPID SAND FILTERS

63. DIATOM FILTERS

64. DIATOM FILTERS the operation of these filters is very similar to that of cartridges, except for the inclusion of diatoms that are fossilized elements that act as the main agents that are responsible for water filtration. On the contrary that the sand or the cartridges, it treats of the elements with more filtering power of the market, obtaining a very good result so that the water of the pool has the best possible quality. And is that the diatoms absorb all the dirt in the water , even those particles that are too small for the human eye to see. Its filtering capacity is so high that it reaches 10 microns.

65. Diatomite is a siliceous, sedimentary rock of Biogenic origin, mainly constituted by fossilized remains (skeletons) of the diatoms frustules, presenting different degrees of consolidation. It is formed by the sedimentary accumulation of the microscopic skeletons of unicellular algae. It is composed of fossilized opaline skeletons of the diatom; The skeletons are composed of amorphous silica.

66. The diatomite is formed by the sedimentary accumulation to form large deposits with a sufficient thickness to have a commercial potential. Pure diatomite is formed by opaline or hydric silica, may contain small amounts of inorganic components such as alumina, iron, earth and alkali metals, as well as other minor constituents. The diatomite also contains unusual amounts of free water, which can vary from about 10% to 60%. The main deposits in the world, have been characterized as dry type deposits, where the diatomite is presented as light weight material. The apparent density (dry basis) in situ varies from 0.32 to 0.64 ton / m3.

67. Microbiological Treatment of gas sources

68. Introduction Technologies such as incineration, chemical oxidation, absorption and adsorption have been used industrially for treatment of gaseous effluents from point emissions from stationary sources. These conventional technologies suffer from significant drawbacks such as high cost and limited operating efficiency.

69. Where to apply ? Volatile organic compounds (VOCs) generated by the chemical, petrochemical and food industry , or reduced organosulfur compounds in papermaking, synthetic sponges and textiles such as rayon . Important also are the treatment of gaseous effluents generated in the industry related to waste treatment, such as facilities composting, bioremediation, wastewater collection, wastewater treatment plants wastewater (urban and industrial) or landfills .

70. Where to apply ? Facilities that are characterized by complex mixtures of generating odors , generally due to compounds derived from bacterial activity under anaerobic conditions and aeration processes usual in most waste treatment systems. By contrast, emissions of particulates and other combustion gases to be treated by systems physicochemical treatment as biological treatments are not effective.

71. Incineration The process itself consists of oxidation by incineration of pollutant emissions in furnaces operating at temperatures above 700º C, in the case of regenerative thermal oxidation, or close to 400° C using catalyzers . Advantages Ease of use, due to the total automation of the process Cleanliness and comfort of treatment as it does not generate any waste Operating economy

72. Incineration Types of oxidizers Recuperative Thermal Oxidation Regenerative Thermal Oxidation Catalytic Thermal Oxidation Applications Printing of paper/tissue Graphic arts in general Manufacturing of varnish/paint Application of special coatings Surface Treatment Specific treatment of electronic compounds

73. Chemical oxidation Chemical oxidation can help reduce risks and reduce VOCs mobility Reduces volatile organic compounds and semi-volatile organic compounds in soil, groundwater, and NAPL non aqueous phase liquid (coal tar or heavy oil) Reduces the volume and thickness of NAPL Reduces the mobility of the remaining NAPL by increasing the NAPL viscosity

74. Absorption In most of the occassion pollutants contained in gases to be treated are susceptible to be oxidized or absorbed in alkaline or acidic medium. So nitrogen derivates (NH 3 ,ammoniac , amino group R-NH, etc) are susceptible to be absorbed in acidic medium while sulfur derivatives (H 2 S hydrogen sulfide, thiol group R-SH, disulfides R-S-S-R, etc) are likely to be absorbed in alkaline medium or susceptible to oxidation. The organic carbon derivatives ( aldehyde group R-COH, R-CO-R and VOC in general) in some case can be decompose into CO 2 and H 2 O when subjected to energetic oxidation.

75. Absorption ADVANTAGES Without limiting flow to treat High efficiency Most common reagents used Totally automated process, so keeping human interventions to a minimum

76. Absorption APPLICATIONS It is a very used technology in the treatment of mid-high flows: Waste water treatment plants : Pumping stations, thickeners, pre-treatment and deshydration . Composting MBT plants Food industry : Odours coming from sludgeries , treatments of animal fats, fish processing plants Chemical and pharmaceutical industry : Gases from reactors vents Incineration gases/ inerting

77. Adsorption The use of high performance medias adsorbs a broad spectrum of pollutants, due to the combination of different absorbing materials. C arbon and impregnated  zeolites Equipments and Equipments consisting of impregnated  aluminas  and thermally activated adsorber . This combination facilitates the dual action of adsorption andinitial oxidation and final alkaline neutralization obtaining a great high efficiency. They have the advantage of having a  higher capacity for adsorption of pollutants than traditional activated carbon , and a larger spectrum of contaminants that can be removed. Also can work with gases with highmoisture contents.

78. Adsorption Advantages Applicable on saturated gases up to  to 95% humidity at fullefficiency High efficiency in gases with presence of VOC's, H 2 S, NH 3 , R-SH, R-NH Easy to assemble Low maintenance costs (regeneration, renewal and energy consumption) Reduced space lay-out

79. Adsorption Applications It is a technology used in the treatment of lower-medium flows, such as: Industrial applications with high variety and pollutant concentration Wastewater treatment plants:  Pumping station,  thickeners,pretreatment  and dehydration Food industry : In particular the treatment of gaseous emissions from roasting processes, processing and cooking fats Chemical Industry : Elimination of volatile organic compounds(VOC's), gases from reactor vents and heavy metal removal