Publisher Summary This chapter describes land treatment of wastewater and discusses the selection and design of system for land treatment. Minimum impact on the environment and minimum total cost of operation are the two main design criteria for land treatment of liquid waste. The choice of system is largely controlled by soil and hydrogeologic conditions and by the availability of land. The chapter divides land treatment systems into three types: overland flow systems, low-rate application systems, and high-rate application systems. Overland flow systems are used where the soil is too impermeable or the suspended solids content of the wastewater is too high to allow significant infiltration rates, causing most of the wastewater to run off. With low-rate application systems, all wastewater apply infiltrates into the soil, but the dosages are rather small and of the same order as the water requirements of the crop or vegetation. With high-rate application systems, all wastewater again infiltrates into the soil, but the dosage is much greater than that necessary for crop growth.

Land Treatment of Wastewater

Removal of algae from stabilization pond effluents by lime treatment

Swine, cattle, poultry, and other commercial livestock can be infected by numerous pathogenic enteric microbes that are also infectious for humans. Livestock waste generated by concentrated animal feeding operations (CAFOs) therefore may contain human pathogens that can infect humans exposed to them during direct contact with livestock waste or media contaminated with the waste (e.g., surface water, ground water, food crops). This article reviews published literature related to the detection and inactivation of human pathogens in flushed livestock waste (i.e., “wastewater”). Physical, biological, chemical, and energetic treatment technologies are discussed, including research results demonstrating or indicating the potential efficacy of the treatment approaches for pathogen reductions in livestock wastewaters.

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Prospects for Pathogen Reductions in Livestock Wastewaters: A Review

The removal/inactivation of viruses during sewage treatment is reviewed. Almost all of our current knowledge on enteric virus removal is limited to enteroviruses, and research is needed on the removal of other enteric viruses during sewage treatment. Primary treatment removes 0-50% of the viruses initially present, while secondary treatment (biological) can be expected to remove 90-99%. Rotaviruses may not be as effectively removed by secondary sewage treatment as enteroviruses. Tertiary treatment involving chemical coagulation can be expected to further remove large numbers of viruses.

Virus Survival in Wastewater Treatment

The transport of poliovirus type 1 (strain LSc) was studied in Red Bay sandy loam columns that were treated with chemical- or polyelectrolyte-conditioned dewatered sludges and then leached with natural rainwater under saturated flow conditions. Poliovirus was concentrated in the alum and ferric chloride sludges that were produced following the flocculation of virus-seeded raw sewage. Virtually complete inactivation of the virus was observed following the flocculation of raw sewage or the stabilization of alum and ferric chloride sludges with lime at pH 11.5. Poliovirus was also concentrated in polyelectrolyte-conditioned dewatered sludge that was produced from virus-seeded, anaerobically digested sludge. Despite the saturated flow conditions for a sustained period, no viruses were detected in the leachates of the soil columns that were treated with these chemical and chemically treated sludges. Since the viruses were mostly associated with the solids in these sludge samples, it is believed that they were immobilized along with the sludge solids in the top portion of the soil columns.

Poliovirus retention in soil columns after application of chemical- and polyelectrolyte-conditioned dewatered sludges.

Phosphate removal from aqueous solutions by precipitation with calcium and aluminum results in large poliovirus Type I and bacteriophage T2 removals. Tests conducted in distilled water-phosphate solutions and filtered domestic wastewater effluent are described. The Freundlich isotherm is used to predict the removal of the two viruses from distilled water solutions. The pH during precipitation affects poliovirus removals. The mechanism of removal is believed to be mostly by chemical adsorption with some physical sorption occurring simultaneously. This is concluded from the inability to recover all viruses from the sludge. The sludge represents a potential health hazard and must be carefully handled. Virus removals are greater in distilled water-phosphate solutions than in wastewater treatment plant effluent. Results are extended to full scale treatment plants indicating that virus removals in excess of 98% and 92% may be expected from precipitation processes using aluminum or calcium, respectively.

Dirk R. Brunner

Papers

Virus Inactivation during Phosphate Precipitation