The Rehabilitated Mudor sewage treatment plant at James Town was monitored over a period of 4 months (October 2017 to January 2018). This study analyzed the physical, chemical and biological parameters of the raw sewage and the treated effluent from the plant. The result indicates that the total removal efficiencies were 98.8%, 91.2%, 62.8%, 28.6%, 81.7%, 43.6%, 82.5% and 99.6% for BOD, COD, TSS, Nitrate-Nitrogen, Phosphate-Phosphorus, Ammonia-nitrogen, Sulphate and faecal coliform respectively. More than 13 parameters needed to be met according to the Ghana Environmental Protection Agency (EPA) guideline were satisfactorily met whiles ammonia, total suspended solids and phosphate were slightly out of range. From the results obtained, the overall performance of the rehabilitated plant was satisfactory and has seen some improvement with respect to the former recorded performance of the plant. With monitoring operation parameters for waste water plants discharge guidelines becoming stringent over the past years, it could be said that management of the Mudor rehabilitated treatment plant is on the right cause with full scale operation of the plant barely less than a year. Increase in the process steps through rehabilitation resulted in several significant improvements in effluent quality parameters.
Environmental sanitation is an essential factor contributing to the health, productivity and welfare of the people of Ghana. It is identified in Ghana’s programme of economic and social development set out in “VISION 2020” as a key element underlying health and human development [
Many small-scale municipal treatment plants are established in municipalities but a great number of them are not working at all or are not working with high performance [
The Mudor waste water treatment plant uses the Up-flow Anaerobic Sludge Blanket (UASB) reactor as a unit for sewage treatment (
microbial solids produced in these reactors are separated by process of sedimentation with most portion of the settled solids recycled back to the bioreactors so as to have high solids concentrations as well as rates of reaction (
In this context as also highlighted by the works of Belhaj [
The plant was monitored by measuring the characteristics of the process parameters of both influent and effluents to assess the overall performance of the plant for sixteen weeks (four months). This paper presents an overview of the rehabilitated Mudor waste water treatment plant in the Greater Accra region of Ghana.
The study was conducted at the rehabilitated Mudor waste water treatment plant located in the greater Accra region of Ghana (
by the Accra Metropolitan Area (AMA) as a sanitary site. The Mudor waste water was constructed by the Taysec construction and was commission in the year 2000. The plant was shut down after some few years of operations due to maintenance issues and lack of financial commitments and rehabilitated into operation in the year 2017. The total land area for the plant is 6.3 acres, situated less than 20 meters east-ward from the Korle-Lagoon.
Composite samples were made from each process unit daily. For each day, the composite sample was made from hourly sampling of the effluent from each of the process units. Each of the daily composited sample contains 24 different number of samples (1 sample for each hour in a day). For each hourly sampling, about 200 ml of the respective unit effluent was taken and transferred into the controlled composite sample container. This was repeated for a period of sixteen weeks and a total of about 120 composite samples were used for the laboratory analysis. The laboratory studies were conducted at the Lavender Hill Faecal Treatment Plant Lab located on the same enclave of the Mudor treatment plant. Sampled (composite) waste water for the present research was selected from the various treatment units of the Mudor waste water treatment plant and process parameters analyzed, in terms of their COD which was measured after potassium dichromate digestion with HACH instrument (DR1900), BOD5 test method APHA 5210, Total Suspended Solids [
The influents and effluents of the plant processes were analyzed for PH, dissolved oxygen, turbidity, Chemical Oxygen Demand (COD), Total Solids (TS), Biochemical Oxygen Demand (BOD), Nitrate-Nitrogen (NO3-N), Ammonia-Nitrogen (NH3-N), Phosphate-Phosphorus (PO4-P) and Faecal Coliform (FC)
Most microbial life occurs within narrow pH range, it is typically evidence to be 6 - 9. Biological treatment of waste water is of great concern in relation to the hydrogen ion concentration. Influent waste water with extremely high or low pH values are difficult/impossible to treat with biological means. Treatment plant effluent water with High or low pH ranges may affect the natural waters in the recipient as well [
In order to maintain the optimal performance of full scale UASB plant or activated sludge plant, Solid Retention Time (SRT) should be changed with temperature in a dynamic way. The average temperature ranged recorded was 25.38˚C, 24.06˚C, 23.44˚C, 23.6˚C and 24.49˚C indicative of influent, effluent from the UASB reactors, effluent from the tricking filter, final settling tank effluent and the final effluent respectively, the plant can be classified as being operating at low temperature range of 20˚C - 23˚C and or moderately high temperature thus less than 28˚C. This temperature range phenomenon is consistent with the previous work [
The EC of water, like TDS, is an indicator of total salt content of the water [
Turbidity values recorded ranged from 391 - 858 NTU and 12 - 39 NTU for the composite of influent and effluent respectively. High turbidity range is as a result of suspended solids in the form of organic constituents in the waste water. High turbidity values were significantly reduced throughout the various process stages, getting effluent values to be within the acceptable value of EPA guideline of 75 NTU. The final effluent being discharged yielded an average of 20.71 NTU (
Reduction in turbidity values is as a result of degrading of organic by microbial organisms in the waste water. Total solids values recorded ranged from 100 - 1300 mg/l and 100 - 400 mg/l for the composite of influent and final effluent respectively. The overall removal efficiency of the plant from the influent to the final effluent was 96.6% (
Average colour recorded was 191.3 TCU for the final effluent discharge (
Dissolved oxygen values ranged from 0.00 - 0.28 mg/l and 1.02 - 3.07 mg/l for the composite of influent and effluent respectively. UASB reactors recorded
Parameter | Final influent mean values | UASB reactor effluent | Trickling filter effluent | Final settling tank effluent | Final effluent mean values | Total efficiency of the plant (%) | EPA Ghana guidelines, 2000 |
---|---|---|---|---|---|---|---|
pH | 8.96 ± 0.98 | 6.7 ± 0.19 | 7.51 ± 0.13 | 7.5 ± 0.14 | 7.45 ± 0.14 | - | 6-9 |
Dissolved oxygen (mg/l) | 0.46 ± 0.26 | 0.58 ± 0.21 | 5.26 ± 0.32 | 4.24 ± 1.08 | 4.24 ± 1.08 | - | - |
Turbidity (NTU) | 1923 ± 646 | 265 ± 44 | 207 ± 62 | 125 ± 50 | 122 ± 5e0.27 | - | 75 |
Total solids (mg/l) | 3200 ± 2571 | 1011 ± 130 | 1038 ± 135 | 966 ± 94 | 958 ± 93.78 | 68.8 | - |
COD (mg/l) | 3173 ± 1528 | 340 ± 74 | 310 ± 69 | 145 ± 21 | 146 ± 20.62 | 94.4 | 250 |
BOD (mg/l) | 1206 ± 397 | 73 ± 16.2 | 42 ± 114 | 23 ± 5.7 | 23 ± 5.74 | 98.1 | 50 |
Ammonia-nitrogen (mg/l) | 4.3 ± 1.73 | 19.6 ± 2.4 | 7.9 ± 1.4 | 2.6 ± 0.7 | 2.6 ± 0.68 | 39.5 | 1.5 |
Nitrate-nitrogen (mg/l) | 29 ± 2.82 | 6.0 ± 1.6 | 16.6 ± 2.5 | 22.1 ± 0.83 | 22.1 ± 0.83 | 23.8 | 0.1 |
TKN (mg/l) | 52.6 ± 4.11 | 93.1 ± 6.5 | 60.7 ± 2.25 | 43.1 ± 1.2 | 43.1 ± 1.15 | 17.4 | - |
Phosphate-phosphorus | 2.31 ± 0.14 | 1.03 ± 0.17 | 1.47 ± 0.53 | 0.5 ± 0.14 | 0.5 ± 0.14 | 78.3 | 2 |
Faecal coliform (No./100ml) | 9.2 × 105 ± 1.1 × 105 | 2.0 × 105 ± 4.9 × 104 | 1.2 × 105 ± 1.8 × 104 | 2.15 × 102 ± 16.31 | 2.16 × 102 ± 16.31 | 99.9 | 10-100 |
Source: Awuah and Abrokwa, 2008 [
Parameter | Influent (Raw sewage) mean values | UASB reactor effluent | Trickling filter effluent | Final settling tank effluent | Final effluent mean values | Total efficiency of the plant (%) | EPA Ghana guidelines, 2000 |
---|---|---|---|---|---|---|---|
pH | 7.00 ± 0.26 | 7.17 ± 0.34 | 7.93 ± 0.92 | 7.96 ± 0.15 | 8.04 ± 0.10 | - | 6-9 |
Temperature (˚C) | 25.38 ± 1.89 | 24.06 ± 2.58 | 23.44 ± 2.28 | 23.6 ± 2.46 | 24.49 ± 1.99 | - | ˂30 |
Conductivity (µS/Cm) | 1591 ± 176.7 | 1977 ± 280 | 1729 ± 234 | 1655 ± 319 | 1383 ± 428 | - | 1500 |
Dissolved oxygen (mg/l) | 0.05 ± 0.08 | 0.25 ± 0.26 | 1.49 ± 0.72 | 1.62 ± 0.46 | 1.76 ± 0.70 | - | - |
Turbidity (NTU) | 607.3 ± 143 | 122.9 ± 21.73 | 60.11 ± 30 | 19.43 ± 5.9 | 20.71 ± 7.0 | 96.6 | 75 |
Total solids (mg/l) | 740.4 ± 313 | 340 ± 140 | 314.3 ± 128 | 300 ± 133 | 260.3 ± 101 | 64.8 | 50 |
COD (mg/l) | 1483 ± 750 | 252 ± 81 | 246 ± 116 | 129.3 ± 56 | 129.9 ± 53 | 91.2 | 250 |
BOD (mg/l) | 2095 ± 294 | 68.21 ± 9.26 | 36.12 ± 4.22 | 27.59 ± 6.9 | 23.88 ± 4.50 | 98.8 | 50 |
Oil and grease (mg/l) | 19.62 ± 0.7 | 9.84 ± 0.7 | 3.38 ± 0.4 | 2..09 ± 3.5 | 3.77 ± 0.3 | 0.54 ± 0.5 | 5 |
Colour (TCU) | 5389 ± 307 | 2496 ± 20 | 252.1 ± 47 | 193 ± 11.16 | 162.3 ± 13.4 | 97.0 | 200 |
Ammonia-nitrogen (mg/l) | 66.88 ± 4.10 | 307.9 ± 17.19 | 121.7 ± 21.68 | 39.57 ± 3.94 | 37.73 ± 4.14 | 43.6 | 1 |
Nitrate-nitrogen (mg/l) | 354.6 ± 49.53 | 70.65 ± 1.08 | 195 ± 10.11 | 253 ± 31.81 | 253.2 ± 35 | 28.6 | 50 |
Sulphate (mg/l) | 375.5 ± 53.4 | 112.7 ± 29.2 | 79.57 ± 6.8 | 69.13 ± 6.9 | 65.53 ± 5.45 | 82.5 | 200 |
Phosphate-phosphorus | 36.83 ± 4.0 | 7.17 ± 0.34 | 22.42 ± 0.12 | 8.18 ± 2.52 | 6.71 ± 0.63 | 81.7 | 2 |
Faecal coliform MPN/100ml) | 8.9 × 105 ± 0.7 × 105 | 2.7 × 105 ± 0.4 × 104 | 2.6 × 105 ± 0.4 × 104 | 3.02 × 102 ± 16.31 | 3.78 × 102 ± 16.31 | 99.6 | 400 |
values ranging from 0 - 0.83 mg/l and 0.62 - 2.86 mg/l was recorded for the trickling filters. The analysis showed low DO values for the influent and this can be attributed to high microbial load in the influent waste water that has utilized maximum amount of the oxygen. The flow of waste water through sewered network could also result in the low DO values. Increased DO values in the UASB, trickling filters and the final effluent are as results of reduction in the microbial load in the waste water and the flow of effluents through open channels. High DO values recorded in the effluent is an indication of good effluent quality with respect to DO and can be discharged into the environment without causing any health implications. The observed trend with respect to this parameter is consistent with the previous work reported [
Composite samples of influent (raw sewage) and effluent COD from the UASB recorded ranged from 760 - 3600 mg/l and 110 - 400 mg/l respectively. The influent samples showed high values of COD; influent and effluent values showed wide variance as a result of high efficiency of the UASB reactors in removing organic material from the waste water. The removal efficiency of the UASB reactors was 88.9% which is higher than the removal efficiency stated by Awuah & Abrokwa [
Values recorded for BOD were 1950 mg/l, 79 mg/l, 45 mg/l and 27 mg/l for the influent (raw sewage), UASB, Trickling filter and the final settling tank effluent respectively. The various treatment units of the plant significantly reduced the BOD concentrations. The final effluent quality is very much desirable as it falls within the EPA required regulation of 50 mg/l and this is consistent with the earlier work [
Taking note of
Ammonia-nitrogen recorded mean values of 66.88 mg/l for the influent, 307.9 mg/l for the UASB reactors effluent. It was observed that there was an increase in the monitored NH3-Nvalues for UASB reactors, this observation was noted in the previous work conducted [
Presence of Sulphate even in low concentrations has the potential to pose serious cathartic effect on humans. The adverse consequence of the presence of sulphate can also be mention on its ability to increase salinity and inhibits some advanced waste water treatment processes. Sulphate recorded mean values of 375.5 mg/l for the influent, 112.75 mg/l in the UASB reactor effluent. The removal efficiency for the UASB reactors was 70%. Values recorded for other process parameters was, 79.57%, 69.13% and 65.53% for trickling filter effluent, final settling tanks effluent and final effluent respectively. The overall sulphate removal efficiency of the plant was 82.5%. The final effluent discharge value falls within the recommended acceptable EPA limit of 200 mg/l. The results obtained from the plant can be said to be very good. Previous literature on the plant [
Considering all the nutrients monitored, the effluent had nitrate to be very high in concentration followed by sulphate in all the samples monitored overtime and the nutrient concentrations were found to be in the order: PO 4 3 − < NH3 < SO 4 2 − < NO 3 − . This observed trend of nutrient in water where the anionic nutrients were found to be higher than ammonia is consistent with the work of Akoto [
The use of Faecal indicator organisms (FIO) have been extensively used to evaluate water quality by many researchers, some have historically led to the public health protection concepts [
Parameters | Awuah & Abrokwa (2008) | This Work | EPA guideline |
---|---|---|---|
FINAL EFFLUENT | |||
pH | 7.45 ± 0.14 | 8.04 ± 0.10 | 6-9 |
Temperature (˚C) | - | 24.49 ± 1.99 | ˂30 |
Conductivity (µS/Cm) | - | 1383 ± 428 | 1500 |
Dissolved oxygen (mg/l) | 4.24 ± 1.08 | 1.76 ± 0.70 | - |
Turbidity (NTU) | 122 ± 5e0.27 | 20.71 ± 7.0 | 75 |
Total solids (mg/l) | 958 ± 93.78 | 260.3 ± 101 | 50 |
COD (mg/l) | 146 ± 20.62 | 129.9 ± 53 | 250 |
BOD (mg/l) | 23 ± 5.74 | 23.88 ± 4.50 | 50 |
Oil and grease (mg/l) | - | 0.54 ± 0.5 | 5 |
Colour (TCU) | - | 191.3 ± 46 | 200 |
Ammonia-nitrogen (mg/l) | 2.6 ± 0.68 | 37.73 ± 4.14 | 1 |
Nitrate-nitrogen (mg/l) | 22.1 ± 0.83 | 253.2 ± 35 | 50 |
TKN (mg/l) | 43.1 ± 1.15 | - | |
Sulphate (mg/l) | - | 65.53 ± 5.45 | 200 |
Phosphate-phosphorus | 0.5 ± 0.14 | 6.71 ± 0.63 | 2 |
Faecal coliform MPN/100 ml) | 2.16 × 102 ± 16.31 | 3.78 × 102 ± 16.31 | 400 |
removal contributing to the low value obtained in the final effluent. The most critical microbial load in waste water is faecal coliform counts and the resultant final load in the effluent was found to be less than 400 MPN/100 ml as provided by the Ghana EPA guideline. The overall removal efficiency of the plant was 99.6%.
・ The overall performance of the various treatment units after renovation of the treatment plant was satisfactory.
・ Almost all of the monitored physico-chemical and microbiological parameters met the Ghana EPA guidelines except ammonia-nitrogen, phosphate and suspended solids which exceeded the regulations guidelines.
・ Final effluent discharge from the treatment plant into the Korle-Lagoon may not cause health risks or any environmental related problems.
・ The plant performance is currently higher (after renovation) than the one reported in literature before the renovation.
・ The effectiveness of the rehabilitated Mudor waste water treatment plant is a wakeup call for political will to be candled and invest in the area of sanitation especially in the rehabilitation of the existing WWTP that have not been operational for several years now in the country.
・ The efficiency of the plant is also a confidence build up in the handlers of the plant (Sewerage Systems Ghana Ltd.) capabilities to rehabilitate and operate sewage and waste water treatment plants in Ghana.
The authors would like to extend their profound gratitude to Sewerage Systems Ghana Ltd., the executive chairman (EC) of the Jospong group of companies (JGC), as well as the board and management of Sewerage Systems Ghana ltd.
The authors would like to declare that, we have no significant competing financial, professional or personal interests that might have influenced the performance or presentation of the work described in this manuscript.
Ahmed, I., Ofori-Amanfo, D., Awuah, E. and Cobbold, F. (2018) Performance Assessment of the Rehabilitated Mudor Sewage Treatment Plant at James Town Accra-Ghana. Journal of Water Resource and Protection, 10, 725-739. https://doi.org/10.4236/jwarp.2018.108041