Monitoring the Wastewater Treatment Efficiency of Oxidation Ponds at Chokera, Faisalabad

Treatment efficiency of the sewage stabilization ponds at Chokera, Faisalabad was carried out with respect to the parameters (i.e. BOD 5 (Five Days Biochemical Oxygen Demand), COD (Chemical Oxygen Demand), pH, Turbidity, TS (Total Solids), TDS (Total Dissolved Solids), Copper, Lead, etc.). Parameters under investigation were monitored at six different locations (i.e. Influent of treatment plant, Influent of anaerobic Ponds, Effluent of Anaerobic Ponds, Effluent of Facultative Ponds, Drain before disposal of treated sewage and Drain after mixing with treated sewage). The testing was done during the low flow season i.e. from December 2015 to January 2016 in Environmental Engineering Laboratory, Department of Civil Engineering, The University of Lahore, Pakistan. BOD 5 removal efficiency of the treatment plant was found 30.08 against designed value of 90% removal. The removal efficiency of COD, TS, TDS, pH, Turbidity, lead and Copper was found 36.56, 22.43, 30.40, 3.43, 73.50, 34.13 and 41.15%, respectively. The maximum removal was of turbidity which is 73.50% but still none of the parameters of the effluent were meeting the PEQS (Punjab Environmental Quality Standards) 2012 except pH and TS. The reasons of low efficiency included lack of funds by government for operation and maintenance of the ponds, increased population, mixing of industrial sewage with domestic and less attention to maintain the performance of Ponds.


INTRODUCTION
T he problem of water pollution is being experienced by both developing and developed countries.
Various categories of substances are being introduced by anthropogenic activities which give rise to water. Organic and inorganic substances, pathogenic organisms, plant nutrients and oxygen demanding substances are the common types of pollutants [1].
Ground water and surface water pollution is due to the industries that are based on wet processes, add the considerable amount of treated and untreated wastewater into environment [2].
for discharging about 300-400 million tons of solvents, heavy metals, toxic sludge, and other waste into receiving water Bodies [3].
In recent years, reuse of treated effluent is getting a mounting awareness as a reliable source of water. In developed countries, the major consideration for treated wastewater reuse is planning and implementation of water resources. To reuse the treated effluent, some countries like Singapore, Saudi Arabia and Jordan have their national policies through which they have made extensive improvement in this regard [4].
Various Treatment Systems are being used worldwide such as suspended growth and attached growth processes. Sewage Stabilization Ponds are one of the suspended growth process which are normally employed to treat domestic sewage but they can also be used to treat industrial wastewater. Waste stabilization ponds are considered to be economical and best treatment option for a developing country like Pakistan where 61% population lives in rural and semi-urban areas. These are cost effective due to little use of mechanical equipment, low maintenance, less requirement of skilled labor, less power requirement, use of local materials of construction and less land cost because they are usually constructed in rural areas of the developing countries [5][6][7][8].
Oxidation process is directly proportional to the addition of organic matter that indicates increase in consumption of DO (Dissolved Oxygen). Strength of wastewater and requirement of DO is usually measured in terms BOD 5 due to the relationship of oxidation process and organic matter. Greater number of species available in the aquatic system require DO in high concentration [9].
In wastewater treatment, through waste stabilization ponds, two types of processes (i.e. methanogenesis and acidogenesis) can occur that can affect the pH.
Methanogenesis process controls the pH within neutral range and acidogenesis causes the drop in pH due to growth of fatty acids [10]. Hodgson, [11] and Ayisah [12] also reported the neutral range of pH [11][12][13]. Ponds) to yield high quality effluent is missing. The primary and secondary ponds are lined with impermeable soil to secure the groundwater below treatment system.
The treated effluent quality is not fit for crops due to the absence of maturation ponds [16].
Present study was carried out to monitor the performance of WSPs as well as to give some recommendations to

Site Specifications
The coordinates of treatment plant are 31 o 27' 32" N and 73 o 0' 20" E which is 14 km away from Centre of Faisalabad. Fig. 1 shows the layout of under study treatment plant which consists of four sludge drying ponds, six anaerobic ponds and six facultative ponds. Table 1 shows the physical aspects of domestic sewage treatment plant of Chokera, Faisalabad. As shown in Table 1 Table 2 represents the location of sampling points and the reason for their selection.

Sampling
Composite samples were collected from six locations (i.e. Date of Sampling at each sampling point is given in Table   1. Sampling was done during cold season (i.e. December 2015 and January 2016) of the year.

Climate
In Faisalabad the intensity of rainfall is about 408 mm/ year. Recorded highest and lowest temperature in this city are 45and 12 0 C, respectively. The maximum wind speed recorded was 94 mph [17].