Purification and utilization of garlic processing wastewater in lotus pond wetlands

Based on the experiments of utilization of garlic processing wastewater in a lotus pond, this study demonstrates that lotus pond wetlands have a remarkable ability to remove organic pollutants and decrease chemical oxygen demand （CODCr）, biochemical oxygen demand （BOD5）, and suspended substances （SS） in garlic processing wastewater. Results also show evident effects of lotus roots on absorption of NH3-N. The pH value in a lotus pond with wastewater discharged was relatively stable. The water quality in the lotus pond reached the class Ⅱ emission standard, according to the Integrated Wastewater Discharge Standard （GB8978-1996）, seven days after pretreated garlic processing wastewater had been discharged into the lotus pond. Garlic processing wastewater irrigation does not produce pollution in the pond sediment and has no negative effect on the growth of lotus roots. Due to utilization of garlic processing wastewater, the output of lotus roots increased by 3.0% to 8.3%, and the quality of lotus roots was improved. Therefore, better purification and utilization results can be achieved.

Irrigation of Romaine Lettuce (Lactuca sativa)Using Wastewater Treated byNon-Conventional Technologies

The aim of this study was to assess the capacity for reuse of wastewater treated in stabilisation ponds and subsequently reclaimed by means of different filtration systems at pilot scale. An analysis of filtered water showed turbidity values of below 5 NTU, a total suspended solids (TSS) content of 7 mg/l, and Escherichia coli values of up to 1.6 log CFU/100 ml. These results fall within the parameters stipulated in RD 1620/2007 Spanish Water Reuse Regulations governing the reuse of reclaimed wastewater for agricultural purposes. The water reclaimed by means of filtration systems was used to irrigate Romainelettuce (Lactuca sativa longifolia), comparing growth with that of the same variety irrigated with water from the supply network. The results showed a mean difference in lettuce growth of up to 300% in favour of the crop irrigated with reclaimed water.

Performance of pond–wetland complexes as a preliminary processor of drinking water sources

Shijiuyang Constructed Wetland（110 hm^2） is a drinking water source treatment wetland with primary structural units of ponds and plant-bed/ditch systems. The wetland can process about 250,000 tonnes of source water in the Xincheng River every day and supplies raw water for Shijiuyang Drinking Water Plant. Daily data for 28 months indicated that the major water quality indexes of source water had been improved by one grade. The percentage increase for dissolved oxygen and the removal rates of ammonia nitrogen, iron and manganese were 73.63%, 38.86%, 35.64%, and 22.14% respectively. The treatment performance weight of ponds and plant-bed/ditch systems was roughly equal but they treated different pollutants preferentially. Most water quality indexes had better treatment efficacy with increasing temperature and inlet concentrations. These results revealed that the pond–wetland complexes exhibited strong buffering capacity for source water quality improvement. The treatment cost of Shijiuyang Drinking Water Plant was reduced by about 30.3%. Regional rainfall significantly determined the external river water levels and adversely deteriorated the inlet water quality, thus suggesting that the ＂hidden＂ diffuse pollution in the multitudinous stream branches as well as their catchments should be the controlling emphases for river source water protection in the future. The combination of pond and plant-bed/ditch systems provides a successful paradigm for drinking water source pretreatment. Three other drinking water source treatment wetlands with ponds and plant-bed/ditch systems are in operation or construction in the stream networks of the Yangtze River Delta and more people will be benefited.