Module 6: EFFLUENT TREATMENT AND RESIDUALS MANAGEMENT

1. Module 6:EFFLUENT TREATMENT AND RESIDUALS MANAGEMENT Program for North American Mobility in Higher Education

2. Structure of this module This module is divided into 3 “tiers”, each with a specific goal: Tier 1.- Basic introduction Tier 2.- Case study of the pulp & paper sector Tier 3.- Open-ended problem

3. Tier 1. Contents: • Introduction • Industrial pollution problems. The petroleum industry. The pulp and paper industry. • Programs for reducing pollution. • Treatment processes. • Process selection. • Volume and disposal reduction.

4. Effluent Treatment and Residuals Management Tier I: Introductory concepts Tier 1

5. G o a l s: • To provide information about the significance of treating effluents from industry and others facilities (or sources) • To extreme the necessity of minimize pollutant concentration in the effluents and reduce the wastes production, and, • To suggest strategies to reduce pollutant wastes production and their emission to the environment Tier 1

6. What is pollution? Pollution means: …changesin the physical, chemical and biological characteristics of air, land and water …harmsfor the human and other living species, and, …degradation of the ecosystems ...the undesirable state of the natural environment being contaminated with harmful substances as a consequence of human activities For example, Water Pollution refers to contaminantsin aquatic ecosystems (streams, lakes, etc) which render them unfit for a particular use. Tier 1

7. Pollutants can reach: • Air • Water • Solid waste This module focuses on water pollution from industrial sources Tier 1

8. Water standards: Drinkable Recreation: swimming, fishing. Irrigation Water impurities may or may not be harmful; it depends on: • The amounts and nature of these impurities, • The next use to which the water will be put, and • The tolerance of these impurities for the next use. Tier 1

9. Types and characteristics of wastewaters: Tier 1

10. Water standards Tier 1

11. Tier 1

12. What is BOD? By definition, BODis the quantity of oxygen required for the stabilization of the oxidizable organic matter present over 5 days of incubation at 20 oC; that can be explained as a measure of the oxygen required by microbes to degrade a sample of effluent. The organic content of the water can be estimated by the BOD. Tier 1

13. Why should we minimize the use of water? Water is such an important part of many manufacturing processes that we must consider Effluent Treatment as a part of the main process because of the great amount always involved. Water is abstracted from aquifers and rivers, treated and supply to industries and homes for different uses; used water is supposed to be treated and discharged again into the rivers. Most of the times, this water returns to its natural environment but unfortunately, with a greater heat content or with some substances added. Tier 1

14. Why should we minimize the use of water? It is also important to minimize use of water because of several reasons: • Fresh water is often scarce. High costs involved operating effluent treatment plants. • Difficult to separate all the elements that pollute water. Tier 1

15. Industrial pollution problems Tier 1

16. Industrial pollution problems: The main pollution problems are related to : • Increasing use of water for agriculture. • The increase of aqueous effluent to receiving water. • Population growth. • Industrial products and services. • The mental, technical, financial, regulatory and institutional barriers to implement preventive modern technologies. RESULTS: Ecosystems decline. Industrialization social costs. The increase of human diseases. Tier 1

17. The petroleum industry Tier 1

18. The Petroleum Industry: Crude oil refining operations involve extracting useful petroleum products from crude oil. Crude oil contains fractions of napthas, gasoline, gas oils, diesel fuel, asphalt, jet fuel and lubrication fuels. Large quantities of production wastes are produced during exploration and production: • Wastewater • Solid waste • Toxic pollutants Tier 1

19. The Petroleum Industry: Production wastes in the petroleum industry can be grouped broadly into 2 classes: • Wastes related to drilling including chemical additives: treatment and disposal of oil drilling wastes takes place either on or off the drilling site. • Wastes related to oil production, primarily produced water: The volume of produced water exceeds the volume of drilled wastes. If environmental quality standards are not exceeded the remainder may be discharged to surface waters. The majority of produced water is disposed of underground through injection wells and it is permitted under U.S. EPA control programs. Tier 1

20. What is refinery effluent? Petroleum refineries use large volumes of water in their processes. The wastewater contains hazardous chemicals: Tier 1

21. Refinery wastes: Emissions from refineries include: • Sulfur oxides • Nitrogen oxides • Benzene, toluene and xylene • VOC • Wastewater containing BOD levels • Heavy metals Tier 1

22. Pollution Approximate Quantities Cooling systems 3.5-5 m3 of wastewater generated per ton of crude. Polluted wastewater BOD 150-250 mg/l COD 300-600 mg/l phenol 20-200 mg/l oil 100-300 mg/l (desalted water) oil 5000 mg/l in tank bottom benzene 1-100 mg/l heavy metals 0.1-100 mg/l Solid waste and sludge 3 to 5 kg per ton of crude (80 % should be considered as hazardous waste because of the heavy metals and toxic organic presence). VOC emissions 0.5 to 6 kg/ton of crude. Others emissions BTX (Benzene, Toluene and Xylene) 0.75 to 6 g/ton of crude Sulfur oxides 0.2-0.6 kg/ton of crude Nitrogen oxides 0.006-0.5 kg/ton of crude Wastes generated: Tier 1 (Pollution Prevention and Abatement Handbook World Bank Group)

23. The pulp and paper industry Tier 1

24. How paper is made: Most of the raw material needed for paper manufacture is supplied by trees. The main steps in the pulp and paper manufacture are raw material preparation, such as wood debarking, and chip making; pulp manufacturing; pulp bleaching; paper manufacturing and fiber recycling. Pulp mills and paper mills may exist separately or as integrated operations. The characteristics of the paper (smoothness, glazed finish) are given by a process called calendering. The paper undergo coating, whereby a thin layer of coating pigment or filler is spread onto the paper surface. Tier 1

25. Pulp and paper industry: The pulp and paper industry has made significant steps toward conserving water and energy. Significant water reductions are achieved through better reuse methods and by separating cooling water from process water. The waste streams generated in this industry are best classified by their origins as show in the next slide. Tier 1

26. Types of waste products in the pulp and paper industry: • Material originated in raw materials (dirt and bark with wood). • Nonfiber components in wood. • Contaminants in waste paper and make-up chemicals. • Reaction products (dissolved wood substance from mechanical or chemical action). • Fiber fragments. • By-products of chemical recovery and combustion. • Fiber and nonfiber process looses and discharges of water, air and heat. Tier 1

27. The pulp and paper industry Water use and effluent discharges: Liquids discharges from the process contain solids, mainly fiber, fillers, and colloidal and dissolved material. The fiber and fillers are minimized and reused. Colloidal and dissolved materials are by-products of the refining of the fibers or carried over from the pulp mill. Discharges of dissolved material are minimized by washing the stock and displaced carryover from pulp mills and by practicing good water reuse strategies that reduce the volume and concentrations of waste in wastewater. Tier 1

28. Programs for reducing pollution Tier 1

29. Government programs for reducing pollution: For sustainable development, governmental pollution prevention programs can best counteract the pressure to invest in “end of pipe” pollution solutions by demonstrating the economic and environmental benefits of a source reduction approach, making technical information available and providing technical assistance. EPA has been working with industry and government representing environmental, community and work force issues to prevent pollution at the source prior to “end of pipe” treatment. Tier 1

30. Government programs for reducing pollution: Laws such as NEPA, TCSA, CAAA and PPA remain outside the scope of most pollution control work. The following options were suggested for USEPA for moving forward interaction in the US: • Add multi-media provisions to the existing regulations. • Correct laws in other policy sectors with environmental measures. • Make NEPA a stronger statute. • Make TSCA a law which can use EPA programs to control and reduce toxic substances. • Establish pollution prevention approaches. Tier 1

31. Programs for reducing pollution: Manufacturers could implement a variety of improved management procedures that would aid pollution reduction: • Environmental audits. Identify (inventory) and correct problems (strategies to achieve reductions) that generate wastes. • Regular preventive maintenance. Inspection, maintenance and replacement of equipment. • Material handling and storage. Emissions of hazardous material must be avoided. There should be labels of all containers and first aid recommendations. • Employee training. Well informed employees are better able to make valuable waste reduction suggestion. • Operating manual and record keeping. Good facility documentation: process procedures, control parameters, hazards and operator responsibilities. Tier 1

32. Environmental programs: Some industries may see no difference between end of pipe pollution control and a front end pollution prevention control. The importance is that those industries may not go beyond the first stage of waste reduction. As the environmental concern deepens, industries have to move further up the production chain: • End of pipe solution to wastes and pollutants; and later • Internal process modifications to reduce emissions and wastes, and eventually • Redesign products to achieve a maximum level of recycling of raw materials and minimization of wastes after the products are used. Tier 1

33. Some measurements to save water: • Keep water effluent streams separated. • Reuse water as close to source as possible. • Recycling whenever it is possible. • Better control of usage with automated systems. • Checking and control of leaks. • When buying new equipment, evaluate water-efficiency models including accessories. • Reducing the quantities of chemicals so that the amount of dilution water will be reduced. Tier 1

34. Reusing water: It is not only possible but necessary to reuse wastewater of a process stream before it leaves the plant accomplished by piping, diluting or treating some of the effluents before using them again. Some plants are now using closed systems, so that there are no water discharges. Zero discharges has been practiced in locations where water is scarce, and may involve technologies for removing suspended and dissolved solids. Complete demineralization is relatively expensive, however, in some cases wastewater discharges can be reduced significantly with other less expensive technologies. Tier 1

35. Treatment processes Tier 1

36. Expectations of a water treatment program: The expectations from a water treatment program should be integrated to include all aspects of the program, from the proposal through to the implementation stages. Tier 1

37. Treatment Program As we will see in the next diagram, the expectations that a good treatment program should give us are listed below: • Overview of a new or existent problem. • Lab study of all system and water composition. • Submit a proposal. • Program implementation. • Monitoring to optimize. • Use of modern treatment techniques. Program under control Tier 1

38. Treatment Program New or Problem System Plant Study Proposal Implement Program System under control Lab Study Follow-up New Product Technology Tier 1

39. Wastewater treatment processes: Wastes are generated by every industrial enterprise, and this wastes can either be liquids or solids. Wastewater treatment can be divided into three stages: • Primary treatment that uses physical operations to remove free oil and/or suspended solids. • Secondary treatment to remove dissolved contaminants through chemical or biological action, and • Tertiary treatment for the removal of residual contaminants. Tier 1

40. Separation order This list shows how separation is carried out: • Primary treatment • Sedimentation • Aeration • Secondary treatment • Tertiary treatment Tier 1

41. Treatments… Primary treatment prepares the wastewater for biological treatment. Large solids are removed by screening, and grit. Equalization in a mixing basin, levels out the flows variation and concentrations. Neutralization, where required, follows equalization. Oils, greases and suspended solids are removed by flotation, sedimentation of filtration. Secondary treatment is a biological degradation of soluble organic compounds from input levels of 50- 1000 mg/l BOD or greater to effluent levels under 15 mg/l. Aerobic treatment in an open vessel is done. After biotreatment, the microorganisms and solids suspended are allowed to settle. Tier 1

42. Treatments… The tertiary treatment remove specific residuals. By filtration, suspended colloidal solids can be removed; adsorption removes organics by granular activated carbon (GAC); and chemical oxidation also removes organic compounds. Tertiary systems have to treat great amounts of wastewater, so they are expensive. When streams rich in heavy metals, pesticides or other substances that may pass through primary treatment and inhibit biological treatment are present, in-plant treatments are necessary. Precipitation, activated carbon adsorption, chemical oxidation, air or steam stripping, wet air oxidation, ion exchange, reverse osmosis are some of the methods useful when in-plant treatments are to be used. Tier 1

43. The tertiary treatment… Tertiary treatment is a polishing step. Its importance is that rather than have to find solutions at the end of pipe, where primary and secondary treatments are used to, it is possible to minimize some toxics or hazardous components in the process before they are combined with other less “hazardous”. Biological treatment usually produces a ’30/20’ effluent with no more than 30 mg/l suspended solids and 20 mg/l BOD. Tier 1

44. Tertiary treatment However, river flows have decreased owing to drought conditions. In these circumstances, new limits are imposed on the quality of the final effluent. The treatment processes beyond the secondary treatment to achieve the required limits inthe processare well known as tertiary treatments. Tier 1

45. In plant treatment Before end of pipe wastewater treatment, a program of waste minimization should be initiated. • Recirculation. In the paper board industry, white water from a paper machine can be put through a save all to remove the pulp and fiber and recycled to various points in the process. • Segregation. Clean streams are separated for direct discharge. • Disposal. In many cases, the total discharge BOD and suspended solids can be reduced by removal of residue in semidry state for disposal. • Reduction. The use of automatic cutoffs can reduce the wastewater volume. • Substitution. The substitution of chemical additives of a lower pollutional effect in processing operations. Tier 1

46. . Wastewater treatment processes:Process selection Tier 1

47. Figure 1. Conceptual treatment program for organic and toxic industrial wastewater For wastewaters containing nontoxic organics, process design criteria can be obtained from lab studies. To define the wastewater treatment problems, a preliminary analysis should be carried out: Organic streams Streams containing heavy metals Mineral streams Toxic and/or nonbiodegradable volatile Biodegradable Source control Figure 3. Equalization Neutralization Oil/grease removal Suspended solids Biological treatment Final disposal Tier 1 (Eckenfelder, 2000)

48. Source treatment: goal • Source reduction is any activity that reduces or eliminates the generation of hazardous wastes at the source • The fundamental goal is to enact changes in consumption, use and waste generation patterns associated with products Tier 1

49. Source treatment: Source treatments involves different definitions of source reduction, but the general consensus appears to be that include any in-plant actions to reduce the quantity or the toxicity of the waste at the source. Examples include equipment modification, design and operations changes of the process and products and substitution of raw materials. Tier 1

50. Figure 2. Laboratory studies for heavy metals/volatile organics start Air or steam stripping VOC/NH3 Equalized sample Chemical oxidation reduction Priority pollutants scan and bioassay Precipitation Heavy metals When toxic and nontoxic organics and inorganics are present, it is necessary to evaluate the existence of heavy metals or volatile organics. Nondegradable/ toxic Fed batch reactor Source treatment Degradable Long-term biodegradation Granular activated carbon Reverse osmosis Priority pollutants scan and bioassay Powder activated carbon Priority pollutants/toxic Ion exchange TDS/inorganics Tier 1 (Eckenfelder, 2000)