Primary effluent filtration in small-scale installations

Abstract

This paper reviews recent technological developments in the filtration of primary effluent. Various studies show that single stage intermittent sand filters attain removal efficiencies of 90% COD, 95% BOD5, 30% TN, 40% TP and 99-99.9% FC at maximum BOD5 loads of around 10 g.m−2.d−1 and hydraulic loads of 5-10 cm.d−1. The permissible organic load can be enhanced by measures such as improved aeration and the use of multilayer filters. Nitrogen removal can be enhanced to 70% by adding a C-source to the filter material or by using two-stage post- and pre-denitrification systems. High organic loading rates (up to around 100 g BOD5.m−2.d−1) are possible with aerated adsorbent foam as a medium.

Oxidative destabilization of dissolved organics and E. coli in domestic wastewater through immobilized cell reactor system

“…The complete mineralization of toxic organics is not normally accomplished by anaerobic treatment and thus the anaerobic treated effluent still contains nutrients, which are initially present in the wastewater . The complete removal of organics through an aerobic biological system and simultaneous removal of suspended solids can be accomplished with a tertiary treatment system like sand filtration (Van Buuren et al, 1999). The objective of using sand filtration in the present study was to remove the suspended solids from the anaerobic digester effluent so that clogging of the CAACO reactor was avoided.…”

Classification of contaminants and treatability evaluation of domestic wastewater

“…In recent years, enhanced primary treatment that utilizes a chemical coagulant to assist the removal of suspended and dissolved contaminants, has drawn wide attention for wastewaters that are not amenable to conventional biological treatment [1], especially in developing countries [2,3]. Many studies have been conducted on the optimization of particle separation [4], utilization of inorganic coagulants and polymers [5], post filtration [6], and post disinfection [7] in the enhanced primary treatment process. Chemically enhanced primary treatment is also recommendable as the first step of wastewater treatment prior to biological treatment to achieve higher removal of organics and nutrients [8,9].…”

Recirculating Sand Filters for Treatment of Synthetic Dairy Parlor Washings

“…However, the success of such a system depends largely on system design. Short contact times, a low C to N ratio (in the recirculation tank), and high recirculation rates all result in poor denitrification rates in a system (Elefsiniotis et al, 1989; Tebbutt, 1998; Van Buuren et al, 1999).…”

“…Again a low C to N ratio of approximately 1:1 in the recirculation tank limited denitrification. Optimal conditions for maximum denitrification occur at a COD to NO x –N (nitrate plus nitrite) ratio in the range of 3:1 (Henze et al, 1997; Martinez, 1997; Van Buuren et al, 1999).…”