WASTEWATER TREATMENT PLANT MAINTENANCE INSTRUCTIONS part 1

Transcription

1 WASTEWATER TREATMENT PLANT MAINTENANCE INSTRUCTIONS part 1 General:... 2 Wastewater in areas of scattered settlement... 2 Preventive measures relating to treatment plant maintenance... 2 Operating principles of the treatment plant... 3 Different basic models and equipment levels... 4 Precipitation tank/pre-treatment tank with equipment... 4 Pre-treatment tank/shredder pump with equipment... 4 Renovation package for old precipitation tanks with equipment... 4 Ancillary equipment... 5 Mechanical space... 5 Operating program functioning and use:... 6 Process monitoring... 7 Alarm and reminder functions... 8 Manual operation... 9 Program adjustment... 9 Treatment plant activation Treatment plant maintenance Inspection visit procedures Effluent monitoring container Cleaning Sludge settlement test Sludge removal Poisoning Shut-downs Pumps Pumping and aeration control Estimating the amount of chemical needed Dosage chemical FE Chemical handling Alkalinity and ph regulation Annual service COPYRIGHT ympäristö RAITA environment 1

2 General: These operation and maintenance instructions are intended to explain to property owners and residents how wastewater in areas of scattered settlement is treated in a RAITA wastewater treatment plant. A well-planned and properly installed wastewater treatment system may not function adequately if a property owner or resident does not follow the operation and maintenance instructions. Neglecting maintenance may reduce treatment plant effectiveness and result in inadequate wastewater treatment. This could result in wastewater from the property polluting the environment and groundwater, causing serious health risks, and spreading disease and unpleasant odours. Wastewater in areas of scattered settlement Wastewater is created when water is used for toilet flushing, bathing, showering, food preparation in the kitchen, dishwashing, and laundry. One resident produces approximately litres of wastewater per day. Wastewater is composed of dissolved organic and inorganic ingredients, solids, and micro-organisms, including different kinds of bacteria and viruses. Discharge of wastewater into surface waters, groundwater, and the soil presents environmental and health risks. According to the Decree that came into effect on , properties in areas of scattered settlement are to be equipped with appropriate wastewater treatment systems. Preventive measures relating to treatment plant maintenance Property owners and residents can prevent problems by adhering to the following procedures: Regulating water consumption to decrease treatment plant loading Taking care of regular precipitation tank emptying and excess sludge removal, usually 1 3 times per year (see page 13 for further details about sludge removal) Inspecting the treatment plant once a month. Having the treatment plant serviced once a year. Taking care to prevent any harmful substances from entering the treatment plant. Keeping information about the treatment plant up-to-date (plan, installation, siting, inspections, precipitation tank emptying and sludge removal and possibly any malfunctions and repairs). In addition, care must be taken not to allow any substances that are harmful to the operation of the treatment plant to enter it, such as medical substances, cigarette butts, sanitary napkins, diapers, condoms, large amounts of milk or grease, chemical drain openers, chlorine, antibacterial detergents, solvents, oil, paint or other hazardous wastes (for more information see poisoning, page 15). Only wastewater from toilet flushing, dishwashing and laundry, and showering, bathing, and other washing must be allowed down the drain. Rainwater and melt water, such as runoff from rooftops, yards, and surrounding terrain, must not be conducted to the treatment plant. Inspection of the treatment plant takes about 5 minutes, usually once a month. Annual service is usually conducted by the service company. The treatment plant adjusts its functioning automatically as load conditions vary. COPYRIGHT ympäristö RAITA environment 2

3 Operating principles of the treatment plant 1. Wastewater enters the treatment plant. The first tank chamber (1) is a pre-precipitation chamber that removes solids from wastewater inflow before the actual treatment process begins. Solids disintegrate in the preliminary treatment chamber aided by a biological decomposition process. The first chamber (1) may be omitted (model R) if a shredder pump is used as the pump for the second chamber (2). 2. Following preliminary treatment, wastewater flows into the second treatment plant chamber (2), which functions as a collecting and equalization tank. The treatment plant monitors (3) wastewater inflow and automatically adjusts treatment plant functions according to load variation. In the PA 10 model there are two process tanks that are used successively. 3. Pumping from the second chamber to the third chamber takes place automatically at a certain surface level (A). The equalization storage is the volume difference between surface levels A and B. 4. When pumping has begun, the wastewater in the third chamber (4) begins to undergo fine bubble aeration (5). 5. In the third chamber, the treatment processes that take place in succession are biological treatment, nitrification, chemical addition, clarification and denitrification. 6. During aeration, active sludge in the tank mixes with pre-treated wastewater, and organic ingredients are used as nutrients by microbial communities in the active sludge, starting the biological treatment process. Nitrification happens at the same time, changing the state of nitrogen. At the end of the aeration period, a chemical dose (6) is added to the wastewater, reacting with phosphorus and precipitating it to the floor of the third chamber. Air pumped into the water exits the treatment plant to the roof of the building via ventilation of the drain. 7. After aeration begins the clarification period, during which active sludge precipitates to the tank floor (7) and denitrification occurs at the same time. 8. Following the clarification period, the "clarified liquid", or treated water (8), is discharged from the treatment plant into the environment. 9. The water is pumped through a monitoring container (9), in which a monitoring sample is retained automatically. 10. The effectiveness of aeration may also be increased by pre-aeration of the inflow. 11. The control and alarm centre, fan, chemical dosage pump and tank, and pump controls are situated in the mechanical space (11) above the basin areas. 12. Malfunctions; mechanical problems or bypasses activate the alarm. The alarm light is in the door of the mechanical space (12). The GSM alarm centre forwards alarm information to the desired GSM phones as text messages (ancillary equipment). Alarms are recorded in the operating program memory. 13. The excess sludge produced by the treatment plant may be treated in two ways: 1) Sludge may be removed by tanker lorry 1 4 times per year. 2) Sludge may be treated over a long time by oxygenation and desiccation so that it can be added to compost and utilized on the property. In this case, emptying by tanker lorry is not needed. The treatment plant delivery for this purpose includes R+LI equipment. COPYRIGHT ympäristö RAITA environment 3

4 saostuskaivo/esikäsitte lykaivo - varustuksella (S) Different basic models and equipment levels Standard delivery of all RAITA compact treatment plant models includes self-adjusting operation, including reminder and alarm functions (inspection, maintenance), load counter, malfunction register, and programming backup in case of power outages. The equipment provided with different treatment plant models may vary. Models PA 1 PA 5 are available with precipitation tank/pre-treatment tank equipment (S) or pre-treatment tank/shredder pump equipment (R). A renovation package (SA) for connection to older systems includes a process tank and all equipment that is part of a normal delivery except for pre-treatment tanks. VANHAT SAOSTUSKAIVOT min tilavuus a 700 l VANHA SAOSTUSKAIVO min tilavuus 700 l Saostuskaivo/ esikäsittelykaivo varustuksella (S) Esikäsittelykaivo/repijäpumppu varustuksella ( R) Esikäsittelykaivo/repijäpumppu varustuksella ( R) Esikäsittelykaivo/repijäpumppu varustuksella ( R) Precipitation tank/pre-treatment tank with equipment Delivery includes a precipitation tank and pre-treatment tank as well as a process tank with standard equipment. Pre-treatment tank/shredder pump with equipment Delivery includes a pre-treatment tank/shredder pump as well as a process tank with standard equipment. Renovation package for old precipitation tanks with equipment COPYRIGHT ympäristö RAITA environment 4

5 Delivery includes process tank with standard equipment as well as other equipment according to the model (SA-S or SA-R). Ancillary equipment GSM alarm centre A GSM alarm centre may be added to treatment plants as ancillary equipment. Reminders and alarms are sent as text messages to a GSM phone. Three phone numbers (e.g. for the user, service company etc.) can be programmed into the GSM alarm centre. Sludge treatment unit A sludge treatment unit may be added to treatment plants as ancillary equipment. The sludge treatment unit pumps excess sludge from the treatment plant process tank into a drying basket, from which it can be emptied into compost. Sludge treatment can be operated manually or by automation. Manual operation is used as needed (usually 1 4 times a year), automatic operation is continuous. UV treatment unit A UV treatment unit may be added to treatment plants as ancillary equipment. UV treatment sanitizes effluent water by killing bacteria. Mechanical space Control functions are situated in the treatment plant control unit, which in turn is situated in the control cabinet. In smaller treatment plants, the control cabinet is in a weatherproof mechanical space next to the process tank. Pumps and chemical dosage equipment are situated in the tanks and their access shafts. In the largest treatment plants, the control cabinet is usually situated in a separate heat-insulated space also containing fans and chemical dosage equipment. COPYRIGHT ympäristö RAITA environment 5

6 Operating program functioning and use: The treatment plant has very high treatment efficiency and reliability and tolerates load variation well. The treatment plant functions are automatically adjusted according to different load conditions. Because of their automated operation, RAITA compact treatment plants are userfriendly and low-maintenance. Separate adjustment procedures are not necessary. Central unit The treatment plant mechanical space contains a central unit that controls treatment plant operation. PÄÄ VIKAVIRTA MUUNTAJA LOGIIKKA ON OFF ON OFF ON OFF ON OFF ON OFF ON OFF KUITTAUS KÄSIKÄYTTÖ ILMASTUS PUMPPU 1 PUMPPU 2 KEMIKAALI MUU The central unit contains the main power switch fault current protection transformer programming logic unit acknowledgement key manual operation switch switches (circuit breakers) for aeration, pumps, chemical pumps The programming logic unit is equipped with a display for information about progress in the treatment process, reminders and alarms. COPYRIGHT ympäristö RAITA environment 6

7 Process monitoring Aeration, the treatment process is in an aeration period that has lasted 0 h 2 min. The aeration period duration is normally 9 h 30 min. The treatment plant operates on 12 hour retention (treatment of two loads per day). The pumping of a new load into the treatment process takes place at the start of the aeration period. Several aeration periods (2 5) may be included in the program to increase effectiveness of nitrogen removal (see program information, page 11). Chemical addition, the treatment process is in a chemical treatment period that has lasted 20 min. The chemical treatment period begins at the end of the aeration period. There may be several chemical treatment periods (2 5) to increase effectiveness of phosphorus removal. The chemical dosage may be adjusted by changing the pumping time (see program information, page 11) Clarification, the treatment process is in a clarification period that has lasted 2 h 06 min. Clarification time is normally 2 h. After completion of the clarification period, pump 2. pumps the clarified liquid. The intermediate aeration window is displayed when the load has gone through the different phases of the treatment process and the treatment plant is waiting for the next load to fill up. 1. this row displays the length of time (1 h 20 min) that intermediate aeration has been continuing 2. this row displays the day of the week (Thursday) and time of day that intermediate aeration began 3. this row shows the date when intermediate aeration began The load counter indicates the number of treated loads and resetting the counter displays the date. Pressing the down arrow switches over to the load counter, and pressing the up arrow switches back. COPYRIGHT ympäristö RAITA environment 7

8 Alarm and reminder functions The treatment plant gives reminders for inspection and maintenance and surface level alarms as needed. Alarm and reminder operations are indicated on the programming unit display and by the alarm light in the door of the mechanical space. The alarm function can also be connected to a property surveillance system or relayed by a GSM robot to a mobile phone, for example (ancillary equipment). An alarm/reminder is acknowledged using the acknowledgement key. Reminders (steady light) The treatment plant is giving a reminder for monthly inspection. If the reminder is not acknowledged in time (48 h), the reminder becomes an alarm. The bottom row indicates the reminder date. Annual service (steady light) The treatment plant is giving a reminder for annual service. If the reminder is not acknowledged in time (48 h), the reminder becomes an alarm. The bottom row indicates the reminder date. Alarms (light blinks at one-second intervals) The treatment plant is giving an alarm about a device breakdown, clog, etc., or about a reminder not acknowledged within 48 hours. Power outages (light blinks at three-second intervals) Alarm about a power outage (models with alternate power supply). COPYRIGHT ympäristö RAITA environment 8

9 Manual operation All devices can be operated independently under manual operation conditions. When manual operation is switched on, the programming unit display indicates "käsikäyttö" (manual operation) and the alarm light blinks. More details are to be found in part 2 of the maintenance instructions. Program adjustment The treatment plant program is adjusted at the time of activation using values appropriate to the site of use. Adjusted levels are recorded in the transaction log. Values adjusted at the time of transaction can be changed later if necessary. Changes should always be recorded in the usage log. The values to be adjusted are usually those for inspection and maintenance reminders. The chemical dosage amounts may also be adjusted, as the estimated quantity of chemical needed changes according to the properties of the clean water supply. When automatic sludge treatment is in use, the amount of sludge per load to be removed can also be adjusted. Other values are adjusted to the so-called default values for achieving sufficient treatment effectiveness (according to the Decree of on wastewater in areas of scattered settlement) and operation that is as reliable as possible. Other values are adjusted as needed. These include the inflow pumping frequency (1 8 periods), aeration frequency (1 5 periods), chemical dosage frequency (1 5 periods), intermediate aeration on/off time, pre-aeration frequency. More details are to be found in part 2 of the maintenance instructions. COPYRIGHT ympäristö RAITA environment 9

10 Treatment plant activation The treatment plant is to be filled with water immediately after installation (if there is no wastewater inflow, clean water is used). Pump and aeration functioning is tested manually (see instructions for manual operation on page 9), and then the operation program is switched on. The biological treatment process is activated after about 2 6 weeks of average loading. The activation of the biological treatment process can be sped up by adding active sludge (100 l or more) from an already active treatment plant into the third chamber when the treatment plant is first put into operation. Operation of the treatment plant is to be monitored regularly during activation, and the activation of the biological treatment process can be observed by the formation of active sludge in the third chamber. The amount of active sludge can be determined by conducting a sludge settlement test (see detailed instructions on page 13). Chemicals are not to be added to the treatment plant while the biological treatment process activation is in progress. When the amount of active sludge exceeds 10 %, chemical dosage may be switched on. Treatment plant maintenance The RAITA compact treatment plant is a bio-chemical wastewater treatment plant developed in Finland. It makes use of the biological active sludge process for removal of organic material, the biological nitrification and denitrification processes for removal of nitrogen, and biological treatment and chemical precipitation for removal of phosphorus. Inspection visit procedures The property owner carries out general inspection: inspecting the appearance and odour of water in the treatment plant basins. inspecting the effluent monitoring container sample checking the amount of chemical Adding the following information to the log: number of loads treated, problem situations, procedures carried out and other observations. excess sludge is removed, chemical added, and the precipitation tank emptied as needed. The time needed for the inspection is 5 30 minutes. More details are to be found in part 2 of the maintenance instructions. COPYRIGHT ympäristö RAITA environment 10

11 Effluent monitoring container The treatment plant is equipped with an effluent monitoring container, which retains a monitoring sample from each treated load. Treated water is pumped out of the treatment plant at the end of the clarification period through a pipe that has a valve. Treated water is collected from this pipe into the monitoring container. It is recommended that the sample in the container be inspected once a week (at least once a month). The sample in the monitoring container should be clear (chemicals may change the colour to a light gray), transparent, and should not contain any solids or visible particles. Look at the sample against the light. CLOUDINESS of the monitoring container sample is usually a result of: non-activation of the treatment process running out of chemical faulty dosage pump poisoning SLUDGE PARTICLES in the monitoring container sample are usually a result of: reaching of sludge capacity low alkalinity of water (surface sludge), add approximately 0.5 dl lime to process tank exceeding of load capacity (water quantity) COPYRIGHT ympäristö RAITA environment 11

12 Cleaning The devices are to be cleaned as needed. A layer of sludge may form in the pipes over the years, impeding flow. Sludge is emptied in connection with the annual service. Sludge settlement test Sludge settlement testing is carried out as needed (in connection with activation, problem situations). The treatment plant has a minimum sludge capacity of 40 % of the third chamber volume. The sludge settlement test is used to measure the amount of sludge and inspect the sludge settlement properties. A sample of 1 l is taken from the third chamber during the aeration period. The sample is allowed to settle in the sample container for half an hour. Settlement is monitored and the settlement of sludge after 30 minutes is recorded (if needed, after 1 hour, 2 hours; the process settlement time is 2 hours). Sludge removal If a sludge treatment unit is used, the amount of excess sludge created by the biological process is very small due to extended aeration, internal sludge collection and circulation. Sludge accumulates in the process tank (excess sludge from the biological process) and in the precipitation tank (pre-precipitation sludge). Excess sludge from the biological process can be removed to the sludge treatment unit (ancillary equipment 4), in which it is separated from the water and dried. The drying basket can be emptied into compost. A sludge treatment unit minimizes the need for sludge removal. Solids collected from pre-precipitation (1) are decomposed and mineralized. The precipitation tank is emptied once a year or less. If R-equipment is used, that is, a shredder pump instead of a pre-precipitation tank, additional sludge removal is not needed. More details are to be found in part 2 of the maintenance instructions. Poisoning The biological treatment process is susceptible to poisoning. Symptoms are a low (1 5) or high (8 15) ph, unpleasant odour, or active sludge rising to the surface. Do not conduct toxic substances into the treatment plant that will destroy the microbial action (e.g. medicines, cigarette butts, milk, grease, chemical pipe clog removers, chlorine, antibacterial detergents, solvents, oil, paint, or other hazardous wastes). If poisoning occurs, try to have the contaminated water removed immediately (by a vacuum lorry) from the treatment plant precipitation tank and pre-treatment tank (storage and equalization tank). In this way you may be able to save the active sludge. If contaminated water has already entered the process tank (the biological process), however, that must also be emptied and the biological process restarted. COPYRIGHT ympäristö RAITA environment 12

13 Shut-downs The treatment plant is designed to operate during normal load interruptions (weekends, even four-week vacations) without detriment to the treatment process. Activity shifts to a "resting" state (intermediate aeration state) automatically. If the shut-down is for a longer period of time (more than 4 weeks), nutrients can be added to the process to keep the microbial activity going. Pumps Standard equipment includes two pumps: 1. pump pumps pre-treated wastewater to the process tank (R equipment uses a shredder pump). 2. pump pumps treated water out of the treatment plant after the filling period ends. 2. pump can be used to remove excess sludge to the sludge treatment unit if needed (manual operation). In addition, the automatic sludge treatment unit equipment includes a third pump that removes sludge from the process tank automatically. Pumping and aeration control The operating program regulates pump and aerator operation. Operation times change automatically with load variation. Processing time varies from 1 to 2 loads per day depending on the amount of inflow. Activities automatically shift to a resting state when wastewater is not entering the treatment plant (vacation times, etc.). It is possible to override the operating program for manual pump operation. Estimating the amount of chemical needed The amount of chemical needed depends on the quality of the wastewater. Since this concerns a chemical reaction in which the precipitating chemical reacts with phosphate in the water, the amount consumed is determined primarily by the phosphorus content of the wastewater inflow - the more phosphorus there is in the wastewater, the more chemical is consumed. Chemical dosing is set to a default value (calculated according to the Decree) for achieving effective dephosphorization under the most common conditions. The operating program automatically adds the correct chemical dosage to the wastewater being treated under varying load conditions. The operating program adjusts chemical pump dosage. It is possible to change the dosage amount if needed, for instance if the water for consumption has highly unusual properties. (see page 10, Program adjustment) COPYRIGHT ympäristö RAITA environment 13

14 Dosage chemical FE The substance is delivered as a prepared solution in 5 l, 10 and 30 l containers. The solution is poured into the treatment plant chemical tank (1). The operating program gives reminders about chemical replenishment (light on top of mechanical space). Always obey the warnings on the container when handling the chemical. The chemical contains sulphuric acid, ferric sulphate, ferrous sulphate, and manganese sulphate. The chemical is corrosive. Chemical handling If accident occurs, any chemical splashed on eyes must be flushed immediately with generous amounts of water (for 15 minutes) and medical attention sought. Any splash on skin must be rinsed immediately with generous amounts of water. If nausea occurs, medical attention must be sought immediately. When handling the chemical, appropriate protective clothing, gloves, and eye or face protection are to be used. Alkalinity and ph regulation The chemical is acidic and reduces the alkalinity of the water (alkalinity is a measure of the capacity of water to resist change in ph when acid is added to it), as does nitrification. Reduced alkalinity is indicated by low ph (less than 6.5) and impeded settlement during the settlement test as well as by surface sludge appearing in the process tank. Alkalinity decreases especially when a long sludge removal interval is being used. Alkalinity is regulated by adding a substance such as lime to the process tank, dl as needed. More details are to be found in part 2 of the maintenance instructions. Annual service An authorized service company carries out annual service (according to the service agreement). The condition of the fan is examined, condition of aerators and aeration pipes, condition of submerged pumps and plumbing, condition of chemical pump and plumbing, surface alarm functioning, usage log inspection, analysis of monitoring container sample and active sludge, process evaluation and comments (in writing). More details are to be found in part 2 of the maintenance instructions. COPYRIGHT ympäristö RAITA environment 14