Biomass and microbial activity in a biofilter during backwashing

Biomass and microbial activity in backwashing processes of a biofilter for tertiary treatment were investigated. The microbial groups revealed new distribution along the biofilter depth after low flow rate backwashing for a short time. Then the start-up process was accelerated by backwashing. The biomass profile and microbial activity profile both varying with depth before and after backwashing, can be mathematically described by quadratic equations. Using the profiles, the difference of oxygen demand can be calculated to determine the airflow rate during backwashing. Combined with the difference between biofilters and rapid gravity filters, analysis of biomass and microbial activity can determine more accurately the required airflow rate during backwashing.

Pond Water Quality and Cyclops Population in Dracunculiasis Endemic Areas of Ogun State, Nigeria

This study investigated the association between Cyclops population and physico-chemical properties of pond water in villages selected from Odeda and Obafemi-Owode areas of Ogun State, Nigeria. Epidemiological data on guinea worm were collected from Global 2000 South-West Zonal Office. Two villages were selected from each of Odeda and Obafemi-Owode LGAs while one village was sampled from Abeokuta North LGA as control. Physico-chemical analysis and microscopic examination of pond water utilized for domestic purpose in the selected villages were conducted. Mean values of 6.78±0.10, 33.00±0.14℃, 1.09＋0.80 mg/L and 1.30±0.25 mg/L were recorded for pH, temperature, DO and nitrate respectively while control had 7.30±0.14, 36.30±14℃2, 2.72±0.14 mg/L and 5.80±0.57 mg/L. These values with the exception of DO and nitrate were within WHO standard but vary significantly （P〈0.05） between the villages. The results further showed that BOD, COD and acidity were positively correlated with Cyclops population during the rainy and dry seasons while temperature, nitrate, pH, and alkalinity have negative correlation coefficients （r=-0.81, -0.91） with Cyclops population during the two seasons. Regression analysis showed that nitrate, BOD and acidity levels explained 67.7 percent, 50.4 percent and 44.5 percent of Cyclops population in the ponds. Guinea worm eradication in endemic rural areas should incorporate ecological strategy.

Measurement of Biological Oxygen Demand （BOD） in Sewage Wastewater Using Modified Inoculums

The objective of this studying was to accurate determination of Biological Oxygen Demand （BOD） through the use of two types of prepared inoculums, the natural activated sludge supplied from conventional wastewater treatment plant and the modified activated sludge prepared from activated sludge of wastewater treatment plant of refinery factory. Analytical method was used to measurement of BOD by preparing the standard curve of BOD in basal medium. The results showed to the large differences in BOD values in basal medium （30-300 mg/L） and conventional wastewater （80-320 mg/L） when they were inoculated with natural and modified activated sludge respectively. It was also found an ability of modified sludge to remove high concentrations of oil and greases.